concepts of occlusion in prosthodontics a literature review part ii

Concepts of occlusion in prosthodontics: A literature review, part I

Affiliation.

• 1 Department of Prosthodontics, Sri Venkateswara Dental College and Hospital, Thalambur, Chennai, Tamil Nadu, India.
• PMID: 26929513
• PMCID: PMC4762337
• DOI: 10.4103/0972-4052.165172

Occlusion and its relationship to the function of the stomatognathic system have been widely studied in dentistry since many decades. This series of articles describe about occlusion in the complete denture, fixed partial denture, and implants. Part I and II of this articles series describe concepts and philosophies of occlusion in complete denture. So far, available research has not concluded a superior tooth form or occlusal scheme to satisfy the requirements of completely edentulous patients with respect to comfort, mastication, phonetics, and esthetics. Since then, several balanced and nonbalanced articulation concepts were proposed in the literature. A balanced articulation appears to be most appropriate because of tooth contacts observed during nonfunctional activities of patients. This article discusses about evolution of different concepts of occlusion and occlusal schemes in complete denture occlusion.

Keywords: Articulation; complete denture; occlusion.

Publication types

Europe PMC requires Javascript to function effectively.

Either your web browser doesn't support Javascript or it is currently turned off. In the latter case, please turn on Javascript support in your web browser and reload this page.

Search life-sciences literature (43,966,551 articles, preprints and more)

• Free full text
• Citations & impact
• Similar Articles

Concepts of occlusion in prosthodontics: A literature review, part II.

Author information, affiliations.

• Rangarajan V 1
• Yogesh PB 1
• Gajapathi B 1
• Ibrahim MM 1
• Karthik M 1

Journal of Indian Prosthodontic Society , 01 Jan 2016 , 16(1): 8-14 https://doi.org/10.4103/0972-4052.164915   PMID: 27134421  PMCID: PMC4832799

Abstract 

Free full text , concepts of occlusion in prosthodontics: a literature review, part ii, v. rangarajan.

Department of Prosthodontics, Sri Venkateswara Dental College and Hospital, Chennai, Tamil Nadu, India

P. B. Yogesh

B. gajapathi, m. mohamed ibrahim, r. ganesh kumar, murali karthik.

This series of articles describes about concepts of occlusion in the complete denture, fixed partial denture, and implants. This article discusses about the evolution of different concepts of nonbalanced occlusion and occlusal schemes in complete denture occlusion.

INTRODUCTION

In continuation with concepts of occlusion in prosthodontics part I where concepts developed to achieve balanced articulation were described, now the different concepts developed to attain the non balanced occlusion are described with their merits and demerits.[ 1 ]

Nonbalanced articulation[ 1 ]

Various concepts proposed to attain nonbalanced articulation. Those are:

Pound's concept[ 1 ]

Maxillary posterior teeth should have sharp palatal cusps which should occlude with opposing widened central fossae of the mandibular posterior teeth to eliminate the deflective occlusal contacts in processed dentures and the teeth should have gold occlusal inlays to maintain vertical dimension at occlusion. Accurate retentive denture bases are a requirement in this concept.

In centric occlusion, the occlusal contact forces are directed toward the ridges [ Figure 1a ]. In the right lateral position, the buccal cusps on the working side are out of contact and the occlusal contact forces are directed toward the lingual side of the lower ridge. There is a tendency of shifting of denture bases on the balancing side [ Figure 1b ].

(a) Pound's concept: In centric occlusion. (b) Pound's concept: Right lateral position

Aull's concept[ 1 ]

Artificial maxillary posterior should have 33° cusp form teeth with full gold occlusal surface

Anterior teeth arranged to meet the requirements of phonetic values

Characteristic of this concept is recording pantographic tracing and transferring it to articulator to eliminate deflective contacts in the posterior arrangement

Accurate retentive denture bases are a requirement in this concept.

In centric occlusion, the contact forces are directed toward the ridges [ Figure 2a ]. In the right lateral position, the canine guidance disocclude the posterior teeth [ Figure 2b ].

(a) Aull's concept: In centric occlusion. (b) Aull's concept: In right lateral position

Hardy's concept[ 1 ]

Nonanatomic maxillary and mandibular posterior teeth are arranged in a flat plane with a minimum overbite

Masticatory forces are directed toward the ridge bilaterally in centric occlusion [ Figure 3a ].

Hardy's concept: In centric occlusion. (b) Hardy's concept: In right lateral position

In a right lateral position, only the buccal cusps on the working side contact if the path of the condyle is not parallel to the occlusal plane. Tilting of the bases may result if extreme gliding contacts are made [ Figure 3b ].

Sear's concept[ 1 ]

Occlusal pivots were introduced by Sear's

Pivot's place the mandible in equilibrium by maintaining the occlusal load in the molar regions

Occlusal contact forces are also reduced in the anterior region of the residual ridges.

In centric occlusion, occlusal contact forces are directed toward the ridges. Pivoting in the posterior region of a flat occlusal plane has been used to reduce temporomandibular joint symptoms [ Figure 4a ]. In right lateral position, only the working side pivot will contact if the path of the condyle on the balancing side is not parallel to the occlusal plane [ Figure 4b ].

(a) Sear's concept: In centric occlusion. (b) Sear's concept: In right lateral position

Kurth's concept[ 1 ]

Artificial posterior teeth arranged incorporating the reverse lateral curve

This concept utilizes a posterior tooth blocks in series of four teeth which were arranged on a flat occlusal plane with a reverse lateral curve and posterior ramp.

In centric occlusion, the contact forces are directed toward the lingual side of the lower ridge [ Figure 5a ]. In the right lateral position, the occlusal contact forces directed toward the ridges on the working side [ Figure 5b ].

Kurth's concept: In centric occlusion. (b) Kurth's concept: In right lateral position

Lingualized articulation[ 2 , 3 ]

In 1927, Gysi introduced the concept of lingualized articulation. In 1941, Payne reported on Farmer's posterior setup that used 30° cusp teeth that were selectively reshaped to fulfill the concept of lingualized articulation and meet the individual requirements of edentulous patients. In effect, the occlusion is lingualized by the elimination of contacts on the buccal cusps and by the anteroposterior arrangement of lower posterior teeth so that their lingual surfaces are on or within the lingual side of a triangle from the mesial area of the lower cuspid to the sides of the retromolar pad.[ 2 ]

Lingualized occlusion is developed to maintain the food-penetration advantages of the anatomic form while maintaining the mechanical freedom of the nonanatomic form. The lingualized concept utilizes anatomic teeth for the maxillary denture and modified nonanatomic or semi anatomic teeth for the mandibular denture.[ 3 ]

Anatomic posterior occlusal arrangements have the mandibular buccal cusps occluding in the maxillary central fossae and the maxillary palatal cusps occluding in the mandibular central fossae [ Figure 6a ]. With lingualized occlusions, only the upper lingual cusps occlude in the mandibular central fossa. The maxillary posterior teeth are rotated slightly to avoid all contact of the buccal cusps [ Figure 6b ].

(a) Normal occlusion and (b) lingualized occlusion

If the horizontal overlap is 3–4 mm between the anterior teeth, balanced occlusion can be achieved before anterior tooth contact at maximum intercuspation. Esthetically vertical overlap of the teeth can be increased [ Figure 7 ].

Overjet: 3–4 mm

When little horizontal overlap between the anterior teeth is acceptable, then the vertical overlap must be reduced to zero to attain balanced occlusion [ Figure 8 ].

Overjet: 0.5–1 mm

Protrusive movement is possible while maintaining balanced occlusion with a minimal vertical overlap of the anterior teeth [ Figure 9 ].

Lingualized balanced occlusion: Protrusion

In left lateral excursive movements, only the maxillary palatal cusps make contact. Selective grinding of the maxillary buccal cusps may be needed to create a clearance between the maxillary and mandibular buccal cusps [ Figure 10 ].

Lingualized balanced occlusion: Lateral excursion

Indications

High priority on esthetics but a nonanatomic occlusal scheme is indicated

Severe residual ridge resorption

Class II jaw relationship

Flabby supporting tissue

When a complete denture opposes a removable partial denture.

The need for bilateral balanced occlusion is based on more favorable stress distribution during parafunctional habits. Nocturnal occlusal parafunction can be eliminated by removal of the dentures while sleeping, but there is still the problem of parafunction during day time. Usually, the desired range of lingualized balanced occlusion can be achieved before the anterior teeth make contact. Anterior tooth position does not compromise the efforts to achieve bilateral balanced occlusion within the suggested range, and the teeth can be arranged to meet esthetic and phonetic requirements. In situations where the anterior teeth would contact before achieving the desired range of bilateral balanced occlusion, the vertical overlap of the anterior teeth can be reduced to approach an incisal guidance of zero. In both situations, a slight compensating occlusal curve will be necessary to achieve continuous posterior contacts anterior to centric relation.[ 3 ]

Advantages[ 3 ]

Both the anatomic and nonanatomic forms are retained

Cusp form is more esthetic compared to nonanatomic tooth form

Good penetration of the food bolus is possible

Bilateral balanced occlusion can be obtained for a region around centric relation

Vertical forces are centralized on the mandibular teeth.

Organic occlusion[ 4 ]

In this concept, the anterior teeth are arranged according to the requirements of esthetics and phonetics. Extreme vertical overlaps producing cuspid guidance are frequently used, resulting in disocclusion of the posterior teeth away from centric occlusion. Characteristic of this concept is the use of pantographic tracings and the transfer of these recordings to an instrument to eliminate all potential deflective contacts in the arrangement of posterior teeth.

This occlusion is based on the muscles and joint determines the mandibular position without tooth guidance and that the teeth in the function should always be passive to the parts of the mandibular movements.

In organic occlusion

The posterior teeth should protect the anterior teeth in the centric occlusion position

The maxillary incisors should have sufficient vertical overlap to provide separation of the posterior teeth when the incisors are in edge-to-edge relation

In lateral mandibular position outside the masticatory movements, the cuspids should prevent contacts on all other teeth.

Monoplane articulation[ 2 , 5 ]

Jones advocated monoplane articulation in 1972. In this concept, a nonanatomic occlusal scheme is used with a few specific modifications. The amount of horizontal overlap is determined by the jaw relationships. The maxillary posterior teeth are arranged first, and the occlusal plane must fulfill certain requirements.

The occlusal plane should evenly divide the space between the upper and lower ridges

The occlusal plane should be parallel to the mean denture base foundation

Finally, the plane should fall at the junction of the upper and middle thirds of the retromolar pads.

Disadvantages

Flat premolars may appear less esthetic

Reported as less efficient in chewing tests

Anterior esthetics needs more overjet and no overbite.

Neutrocentric concept[ 2 , 4 , 6 ]

In 1954, De van formalized guidelines for using flat teeth in his “Neutrocentric concepts,” which stated flat occlusal surfaces should have:

Flat planes in all directions with no inclination at all in respect to the underlying denture foundation

Balance was considered undesirable, as the resulting inclines would create instability of the dentures.

Thus, the teeth are not inclined to form compensatory curves. In mediolateral direction, the teeth are set with no medial and lateral inclination. Thus, the concept of occlusion eliminates any anteroposterior or mediolateral inclines of the teeth and directs the forces of occlusion to the posterior teeth. The occlusal plane is parallel to the mean plane of the denture foundation. This concept was carried out by limiting the mesiodistal extent of the occlusal table to avoid arranging the teeth over the lower molar slope inherent in the posterior portion of the residual ridge. To direct the forces toward the center of support and to reduce the functional forces, the buccolingual width of the teeth is reduced and the number of teeth is also reduced to direct the forces in the molar and bicuspid area of support and to refrain from placing a tooth on the ridge incline.

If the teeth are arranged in any other manner than described above, excessive pressure or pain is caused due to lateral interferences.

There are five elements in this occlusal scheme:

Arrange the teeth in central position in reference to the foundation as the tongue will allow, in order to provide greater stability for the denture. He felt this was the most important factor and that “off ridge” contact for the purpose of balance created more problems.

De van reduced tooth width to 40% to correct tooth proportion. Reduced width of the artificial teeth reduces the vertical stresses on the ridge. In addition, horizontal stresses were also reduced due to the friction between opposing surfaces was decreased. Forces were centralized without encroachment on the tongue space.

Tooth pitch (inclination, tilt) was corrected by placing the occlusal plane parallel to the underlying ridges and midway between them. This positioning directed forces perpendicular to the mean osseous foundation plane. There was no compensating curve and no incisal guidance. Patients were educated not to incise or protrude.

Tooth form was modified using flat teeth with no deflecting inclines. This arrangement reduced destructive lateral forces and to direct the masticatory forces perpendicular to the support. All contacts were in a single plane with no projections above or below the plane to interfere with the mandibular movements.

The posterior teeth were reduced in number from 8 to 6. This decreased the magnitude of the occlusal force and centralized it to the second premolar and first molar area.

Advantages of neutrocentric occlusion

This technique is simple and requires less precise records. Therefore, it is ideal for a patient who has resorbed friable ridges with mobile tissue

By removing inclines, the lateral forces which are destructive to the residual ridges are reduced

Teeth arranged with a neutrocentric occlusal scheme are easier to adjust

Because the neutrocentric technique provides an area of closure and does not lock the mandible into a single position

Also the centric occlusion – centric relation discrepancy introduced by the denture settling would tend to be less destructive because of the unlocked nature of the occlusion

Neutrocentric occlusion is especially indicated in class II (retrognathic), class III (Prognathic), and crossbite cases.

Disadvantages of neutrocentric occlusion

The greatest criticism of this occlusal scheme is that it is the least esthetic as there is no incisal overlap and no posterior cusps

Moving the teeth lingually and altering their vertical position may not be compatible with the tongue, lip, and cheek function. This is offsetted by narrowing of the tooth width

The flat nature of teeth results in impaired mastication.

Physiologically generated occlusion[ 7 ]

Mehringer developed physiologically generated occlusion to harmonize complete denture occlusion, neuromuscular system, and the temporomandibular joint.

The complete denture fabrication is preceded till try in and processing of only maxillary denture is done. After it is polished, a 20 conical disc is attached to the palatal region of the maxillary denture. The lower denture base is attached with plexiglass followed by fabrication of plaster (1/3 talc and 2/3 plaster) and attaching central bearing device exactly fitting into the upper conical disc.

The patient is asked to make chewing and swallowing movements, which created functionally generated paths. Then apply separating medium to obtain maxillary stone cast of generated paths. Lower teeth are arranged according to maxillary cast of generated path. Two-point contacts on working side are eliminated and converted to one-point contact, this increases stability and transmit forces on lingual cusps only.

Lineal occlusion[ 8 ]

A line of occlusal contacts in one dental arch opposing a flat occlusal table in the other dental arch has the potential of creating the smallest lateral component of force against the denture bases. Since the area of contact is minimal, the frictional resistance is reduced. Furthermore, in the dental arch with the line of occlusal contacts, there is no change in the location of the contact during lateral movements. Therefore, the direction of force in that dental arch remains fairly constant.

Locating the line of occlusal contacts

The linear ridge of occlusal contacts may be located in either of the dental arches

The decision as to whether to locate the ridge of contacts in the maxillary or mandibular arch depends on the factors of denture stability and esthetics.

COMBINATIONS OF OCCLUSAL FORMS USED FOR LINEAL OCCLUSION

Maxillary - nonanatomic porcelain teeth; mandibular - porcelain lineal teeth.

Least occlusal wear

Recommended for young, healthy patients with good residual ridges

Adequate interarch space for porcelain teeth required

Exhibits occlusal disharmonies in earlier than occlusion formed with other materials.

Maxillary - plastic teeth (modified); mandibular - plastic lineal teeth

This combination of posterior teeth is the easiest to fabricate and adjust

Disadvantage - susceptibility of the teeth to wear

As wear occurs - flat occlusion

Contraindicated - heavy occlusal wear (bruxism and abrasive diets) and for young patients with good ridges

Advantageous for patients with badly resorbed residual ridges and poor muscle function and who need treatment dentures because of rapid deteriorating or changing ridges.

Maxillary - nonanatomic plastic teeth; mandibular - porcelain lineal teeth

This combination should wear less than does the all plastic combination

The porcelain teeth in occlusal contact will wear very little and tend to maintain a lineal occlusion longer than do plastic teeth

More self-adjusting as mouth changes occur as compared to all porcelain combination.

Maxillary - Anatomic Porcelain Teeth; Mandibular - Nonanatomic Plastic Teeth

When esthetics is of more concern

The maxillary denture is esthetically equivalent to normal cuspal contours in the premolar and molar regions.

Tooth positioning for lineal occlusions

Anterior - No vertical overlap to prevent interference in excursive movements

Mandibular incisors establish the anterior end of the occlusal plane

The posterior landmark is usually the top one-third of retromolar pad

Occlusal plane should be kept as high posteriorly as practical to aid in developing protrusive balancing contacts with a flat plane of occlusion.

Linear occlusion[ 9 ]

The occlusal arrangement of artificial teeth, as viewed in the horizontal plane, wherein the masticatory surfaces of the mandibular posterior artificial teeth have a straight, long, narrow occlusal form resembling that of a line, usually articulating with opposing monoplane teeth.

Teeth are arranged on a flat plane, which extends from the tip of maxillary central incisors to the top of the retromolar papilla. The 2–3 mm of interocclusal clearance is not needed (centric relation recorded at vertical dimension at rest with 0.020 inch vertical clearance). The anterior vertical overlap is absent to provide noninterception in eccentric movements.

The posterior teeth used are nonanatomic with mandibular blade form of teeth. They exhibit bilateral fulcrum of protrusive stability – on protrusion blade form of mandibular second molar contacts maxillary first premolar bilaterally and prevent anterior rotational contact.

In 1976, Koyama, Inaba, and Yokoyama conducted a study on denture wearer preference and masticatory efficiency for balanced, organic (cuspid-protected), and lingualized occlusions in three complete denture patients. Masticatory efficiency was highest for the lingualized occlusion, next highest for the balanced occlusion, and lowest for the cuspid-protected occlusion. The differences in efficiency between lingualized and balanced occlusions and also between lingualized and cuspid-protected occlusions were significant.[ 10 , 11 ]

Woelfel, Mickey, and Allison, in 1962, tested anatomic (33°), modified anatomic (20°), and nonanatomic (0°) teeth to determine the influence of occlusal form on the jaw movements during chewing and the denture movement on its foundation. The shape of the masticatory cycle as shown with cinephotography was not influenced greatly by occlusal form. The closures in all three types of teeth were in close proximity to the posterior border movement. Where the ridges of the subjects were good, the denture base movement was minimal and approximately the same for the three types of teeth, but where the ridge was poor, there was least movement with nonanatomic teeth.[ 10 ]

In 1976, Woelfel and Winter studied three groups of denture wearers over a 5–8-year period. There were 15 subjects in each group wearing anatomic (33°), modified anatomic (20°), and nonanatomic (0°) teeth. The greatest bone loss and closure of the occlusal vertical dimension were observed in the group of denture wearers with nonanatomic posterior teeth and the least in the group wearing anatomic posterior teeth. The nonanatomic group also needed the most adjustments over a 5-year period.[ 10 , 12 ]

Hence, selection of particular concept of occlusion and occlusal scheme in completely edentulous patient depends on maxillary and mandibular jaw relation, residual alveolar ridge resorption, presence or absence of displacive tissues in denture foundation areas, neuromuscular control, patient's mental attitude, and esthetics demands. It is important to explain our patients that treatment with removable complete dentures is not a “definitive” treatment which needs a frequent follow-up to prevent the long-term risks associated with consequences of wearing complete dentures.

Complete denture occlusion is a part of the stomatognathic system and not just merely arranging of maxillary and mandibular teeth. The first and foremost concern is about the health and the preservation of the supporting structures. We need to consider all the factors such as biologic, physiologic, and mechanical that favor the stability of the denture base to avoid deflective or excessive forces transmitted to the underlying structures.

Financial support and sponsorship

Conflicts of interest.

There are no conflicts of interest.

Full text links 

Read article at publisher's site: https://doi.org/10.4103/0972-4052.164915

Citations & impact 

Impact metrics, citations of article over time, article citations, clinical and radiographic evaluation of marginal bone level (bl) in two implant-retained mandibular overdenture with lingualized occlusion (lo): a six-year clinical trial..

Kumari U , Kouser A , Shaik A , J S , J V , Yadav R

Cureus , 15(8):e42810, 01 Aug 2023

Cited by: 0 articles | PMID: 37664310 | PMCID: PMC10473267

Strategic implants and bone morphogenic changes: Survival and clinical success in long-term.

Gangadhar B , Ila A , Kumar R , Ruban B , Punnoose K , Dandekeri S , Babu J S , Swarnalatha C , Nayyar AS

J Orthod Sci , 12:24, 18 Mar 2023

Cited by: 0 articles | PMID: 37351411 | PMCID: PMC10282538

Comparison of Occlusal Digital Analysis Using T-Scan in Orthognathic Surgery with Only Conventional Orthodontic Patients.

Manikandhan R , Manikandan S , Ponvel K , Parameswaran R , Shankar S

J Maxillofac Oral Surg , 22(2):397-409, 08 Feb 2023

Cited by: 0 articles | PMID: 37122794

Immediate Prosthetic Rehabilitation of Marginal Mandibulectomy Post Radiation Case by Single-Piece Implant - A Case Report.

Gaur V , Doshi AG , Gandhi S

Ann Maxillofac Surg , 10(2):501-506, 01 Jul 2020

Cited by: 3 articles | PMID: 33708605 | PMCID: PMC7943986

Choosing the denture occlusion - A Systematic review.

Bhambhani R , Joshi S , Roy SS , Shinghvi A

J Indian Prosthodont Soc , 20(3):269-277, 17 Jul 2020

Cited by: 1 article | PMID: 33223696 | PMCID: PMC7654203

Similar Articles 

To arrive at the top five similar articles we use a word-weighted algorithm to compare words from the Title and Abstract of each citation.

Concepts of occlusion in prosthodontics: A literature review, part I.

Rangarajan V , Gajapathi B , Yogesh PB , Ibrahim MM , Kumar RG , Karthik P

J Indian Prosthodont Soc , 15(3):200-205, 01 Jul 2015

Cited by: 7 articles | PMID: 26929513 | PMCID: PMC4762337

Occlusion for fixed prosthodontics: a historical perspective of the gnathological influence.

Pokorny PH , Wiens JP , Litvak H

J Prosthet Dent , 99(4):299-313, 01 Apr 2008

Cited by: 28 articles | PMID: 18395541

[Occlusal schemes of complete dentures--a review of the literature].

Tarazi E , Ticotsky-Zadok N

Refuat Hapeh Vehashinayim (1993) , 24(1):56-64, 85-6, 01 Jan 2007

Cited by: 2 articles | PMID: 17615993

Occlusal designs on masticatory ability and patient satisfaction with complete denture: a systematic review.

Zhao K , Mai QQ , Wang XD , Yang W , Zhao L

J Dent , 41(11):1036-1042, 01 Aug 2013

Cited by: 9 articles | PMID: 23911601

[Guidelines on occlusion and articulation. Part 1. Overdentures on implants in the edentulous lower jaw].

Wismeijer D , van Waas MA , Kalk W

Ned Tijdschr Tandheelkd , 101(10):388-391, 01 Oct 1994

Cited by: 0 articles | PMID: 11831173

Europe PMC is part of the ELIXIR infrastructure

[Downloaded free from http://www.j-ips.org on Saturday, April 02, 2016, IP: 49.206.1.43]

Review Article

Concepts of occlusion in prosthodontics : A literature review, part I

V. Rangarajan, B. Gajapathi, P. B. Yogesh, M. Mohamed Ibrahim, R. Ganesh Kumar, Prasanna Karthik Department of Prosthodontics, Sri Venkateswara Dental College and Hospital, Thalambur, Chennai, Tamil Nadu, India

Abstract Occlusion and its relationship to the function of the stomatognathic system have been widely studied in dentistry since many decades. This series of articles describe about occlusion in the complete denture, fixed partial denture, and implants. Part I and II of this articles series describe concepts and philosophies of occlusion in complete denture. So far, available research has not concluded a superior tooth form or occlusal scheme to satisfy the requirements of completely edentulous patients with respect to comfort, mastication, phonetics, and esthetics. Since then, several balanced and nonbalanced articulation concepts were proposed in the literature. A balanced articulation appears to be most appropriate because of tooth contacts observed during nonfunctional activities of patients. This article discusses about evolution of different concepts of occlusion and occlusal schemes in complete denture occlusion.

Key Words: Articulation, complete denture, occlusion

Address for correspondence: Dr. B. Gajapathi, Department of Prosthodontics, Sri Venkateswara Dental College and Hospital, Off OMR, Near Navalur, Thalambur, Chennai ‑ 600 130, Tamil Nadu, India. E‑mail: [email protected] Received: 7th June, 2015, Accepted: 13th June, 2015

INTRODUCTION stone, wood, ivory, and metal. Human teeth were also used in early dentures . Every time opposing teeth contact there is Dentate status can affect diet, nutritional status, and general a resultant force. Although this force may vary in magnitude health. A complete maxillary denture can have an impact and direction, it must always be resisted by supporting tissues. on taste and swallowing ability. Masticatory efficiency in Some dentists believe there should be cusps on the teeth and complete denture wearers is approximately 80% lower than that they must be in complete harmony with the dynamics of in people with natural dentition . Other factors that affect chewing ability include mobile teeth, bone resorption, temporomandibular joint function. Other dentists believed reduced sensory perceptions, and motor impairment.[1] The that the teeth should not have cusps. There are numerous early history of the first artificial tooth is obscure, but it concepts, techniques, and philosophies concerning complete is known that 100s of years ago, teeth were carved from denture occlusion.[2,3]

This is an open access article distributed under the terms of the Creative Commons Access this article online Attribution‑NonCommercial‑ShareAlike 3.0 License, which allows others to remix, tweak, and Quick Response Code: build upon the work non‑commercially, as long as the author is credited and the new creations Website: are licensed under the identical terms. www.j-ips.org For reprints contact: [email protected]

DOI: How to cite this article: Rangarajan V, Gajapathi B, Yogesh PB, Ibrahim MM, 10.4103/0972-4052.165172 Kumar RG, Karthik P. Concepts of occlusion in prosthodontics: A literature review, part I. J Indian Prosthodont Soc 2015;15:200-5.

200 © 2015 The Journal of Indian Prosthodontic Society | Published by Wolters Kluwer - Medknow [Downloaded free from http://www.j-ips.org on Saturday, April 02, 2016, IP: 49.206.1.43]

Rangarajan, et al.: Concepts of occlusion in prosthodontics: A literature review CONCEPTS OF COMPLETE DENTURE position, the occlusal contact forces are directed toward the OCCLUSION[2,3] ridges on the working side and away from the ridges on the balancing side [Figure 2b]. Static concept The static relations in occlusion include centric occlusion, Sears concept[ 5] protrusive occlusion, right and left lateral occlusion. All of these Sears in 1922 with his chewing members and in 1927 with relations must be balanced with the simultaneous contacts of channel teeth (both were nonanatomic teeth) developed a all the teeth on both sides of the arch at their very first contact. balanced occlusion by a curved occlusal plane anteroposteriorly The cuspal inclines should be developed so that the teeth can and laterally or with the use of a second molar ramp. In centric glide from a more centric occlusion to eccentric positions occlusion, nonanatomic teeth will exert contact forces toward the without interference and without the introduction of rotating ridges [Figure 3a]. In the right lateral position, the occlusal contact or tipping forces. forces directed toward the ridge on the working side and toward the buccal side of the ridge on the balancing side [Figure 3b]. Dynamic concept The dynamic concept of occlusion is primarily concerned with Pleasure concept[5] opening and closing movements involved in mastication. Jaw In 1937, Dr. Max Pleasure presented an occlusal scheme movements and tooth contacts are made, as the teeth of one called the “pleasure curve,” in which a reverse curve is used in jaw glide over the teeth of the opposing jaw. Movements of the bicuspid area for lever balance, a flat scheme of occlusion the mandible which occur when the teeth are not in contact is set in the first molar area, and a spherical scheme set in the are termed as free movements. second molar area by raising the buccal incline to provide for a Occlusal rehabilitation in complete denture fall into four occlusal concepts [4] • Unbalanced articulation • Balanced articulation • Linear or monoplane articulation • Lingualized articulation.

CONCEPTS PROPOSED TO ATTAIN BALANCED OCCLUSION [5] a b Gysi concept Figure 1: (a) Gysi’s concept: In centric occlusion (b) Gysi’s concept: In 1914, 33° cuspal form was introduced by Gysi. He gave an In right lateral position inclination of 33° to the cuspal inclines to harmonize them with the condylar inclination of 33° to the horizontal. In lateral mandibular movements, cusps contact bilaterally to enhance the stability of the dentures. In centric occlusion, the masticatory forces directed toward the ridges [Figure 1a]. In a right lateral position, the occlusal contact forces are directed away from the ridges. In extreme working lateral position, contacts on both cusps incline, contact force are also directed outside the ridges [Figure 1b]. a b French concept [5] Figure 2: (a) French’s concept: In centric occlusion (b) French’s concept: In right lateral position According to the concept, the occlusal surface of the mandibular posterior teeth had been reduced to increase the stability of the dentures. The maxillary posterior teeth have slight lingual occlusal inclines of 5° for first premolar , 10° for second premolar, and 15° for first and second molars, so that a balanced occlusion could be developed laterally as well as anteroposteriorly by the arrangement of teeth on a curved occlusal plane.

In centric occlusion, half of width of mandibular posterior a b teeth helps to direct the masticatory forces in a buccal direction Figure 3: (a) Sear’s concept: In centric occlusion (b) Sear’s concept: to the mandibular residual ridge [Figure 2a]. In a right lateral In right lateral position

The Journal of Indian Prosthodontic Society | Jul-Sep 2015 | Vol 15 | Issue 3 201 [Downloaded free from http://www.j-ips.org on Saturday, April 02, 2016, IP: 49.206.1.43]

Rangarajan, et al.: Concepts of occlusion in prosthodontics: A literature review balancing contact in lateral position. The distal of the second molar can also be elevated to produce a compensating curve for protrusive balance [Figure 4a].

Pleasure rationalized that the occlusion should be of special design due to the instability of the lower denture. Resultant a forces should be directed vertically and or lingually. In centric occlusion, contact forces are directed toward the ridges [Figure 4b] and in right lateral working position, the occlusal forces are directed toward the lingual side of the lower ridge on the working side and toward the buccal side of the lower ridge on the balancing side depending on the inclination of second molar ramp [Figure 4c]. b c [5] Frush concept Figure 4: (a) Pleasure curve (b) Pleasure’s concept: In centric occlusion In 1967, Frush gave the “Linear occlusal concept,” which (c) Pleasure’s concept: In right lateral position employed an arbitrary articulator balance, followed by intraoral corrections to obtain balance. A single mesiodistal ridge on the lower posterior teeth contacted a flat occlusal surface of the upper posterior teeth set at an angle to the horizontal. The intention was to eliminate deflective occlusal contacts and increased stability. In centric occlusion, contact forces directed toward the ridges according to the linear occlusal concept [Figure 5a]. In a right lateral position, the contact a b forces toward the ridge on the working side and slightly toward Figure 5: (a) Frush’s concept: In centric occlusion (b) Frush’s concept: the buccal side of the lower ridge on the balancing side at a In right lateral position given inclination of 6° [Figure 5b].

Hanau’s quint [2,3,6] In 1925, Rudolph L. Hanau presented a discussion paper entitled, “Articulation: Defined, analyzed, and formulated” [Figure 6].

He believed articulation of artificial teeth was related to nine factors: • Horizontal condylar inclination • Compensating curve • Protrusive incisal guidance • Plane of orientation • Buccolingual inclination of tooth axes • Sagittal condylar pathway • Sagittal incisal guidance • Tooth alignment Figure 6: The articulation quint • Relative cusp height. Where, K = Condyle guidance. He mathematically charted the nine factors and listed the laws I = Incisal guidance. of balanced articulation in a series of 44 statements. Hanau C = Cusp height inclinations. combined the original nine factors and reduced them to five. OP = Inclination of the occlusal plane. OK = Curvature of the occlusal surfaces. Thielemann subsequently simplified Hanau’s factors in a formula for balanced articulation. Trapozzano concept [6] Trapozzano reviewed Hanau’s five factors and decided that [K × I]/[OP × C × OK]. only three factors were actually concerned in obtaining

202 The Journal of Indian Prosthodontic Society | Jul-Sep 2015 | Vol 15 | Issue 3 [Downloaded free from http://www.j-ips.org on Saturday, April 02, 2016, IP: 49.206.1.43]

Rangarajan, et al.: Concepts of occlusion in prosthodontics: A literature review balanced occlusion. He eliminated the plane of orientation since its location is highly variable within the available inner ridge space. He also suggested that the occlusal plane can be located at various heights to favor a weaker ridge [Figure 7]. Trapozzano stated, no need for a compensating curve, as it is obsolete since the cuspal angulation will produce a balanced occlusion.

Boucher concept[2,3,6,7] There are three fixed factors: Figure 7: Trapozzano’s triad of occlusion • The orientation of the occlusal plane, the incisal guidance, and the condylar guidance • The angulation of the cusp is more important than the height of the cusp • The compensating curve enables one to increase the effective height of the cusps without changing the form of the teeth.

The lott concept [2,3,6,7] He stated the laws as follows: • The greater the angle of the condyle path, the greater is the posterior separation • The greater the angle of the overbite (vertical overlap), the greater is the separation in the anterior region and the posterior region regardless of the angle of the condylar path • The greater the separation of the posterior teeth, the Figure 8: The laws of occlusion (Lott) greater, or higher, must be the compensation curve • Posterior separation compensation curve to balance the occlusion requires the introduction of the plane of orientation [Figure 8] • The greater the separation of the teeth, the greater must be the posterior teeth.

Bernard levin’s concept[2,3,6,7] Bernard Levin’s concept of the laws of articulation is quite similar to Lott’s, but he eliminated the plane of orientation [Figure 9].

He has named the four factors as Quad. The essentials are as follows: • The condylar guidance is fixed and is recorded from the patient. The balancing condylar guidance includes the working condyle Bennett movement, which may or may not affect lateral balance • The incisal guidance is usually obtained from the patient’s esthetic and phonetic requirements. However, it can be modified for special requirements, e.g., a reduction of Figure 9: Levin’s concept the incisal guidance is considered to be helpful when the residual ridges are flat balanced occlusion but nearly always are used with a • The compensating curve is the most important factor for compensating curve. obtaining balance. Monoplane or low cusp teeth must employ the use of a compensating curve The Quad is relatively easy to understand and use. • Cusp teeth have the inclines necessary for obtaining The concept of controlling posterior separation is an

The Journal of Indian Prosthodontic Society | Jul-Sep 2015 | Vol 15 | Issue 3 203 [Downloaded free from http://www.j-ips.org on Saturday, April 02, 2016, IP: 49.206.1.43]

Rangarajan, et al.: Concepts of occlusion in prosthodontics: A literature review important goal for achieving a bilaterally balanced denture the eccentric movements and cause inflammation leading to occlusion. accelerated bone resorption. Though some authors argue that these contacts other than mastication are not likely to be made According to Brien R. Lang tooth forms or molds are with any great deal of force, it is seen that many patients enjoy [3,4,7] of four types comfort only when the eccentric balance is present. Equal • Anatomic contact of all posterior teeth (centric occlusion) in centric • Nonanatomic relation is essential for the health of the mucosa.[10-12] • Zero degree • Cuspless teeth. It has been determined by studies that measured the force necessary to masticate food can vary from 5 to 175 pounds with Cuspless teeth are teeth designed without cuspal prominence natural teeth. This wide range of force is due to a person’s choice on the occlusal surface. of foods, the condition of the supporting structures of the teeth, [2] DISCUSSION integrity of the crown , and subject’s muscular development.

Balanced Occlusion is defined as the bilateral, simultaneous, The force used in mastication by denture patients has been studied, anterior, and posterior occlusal contact of teeth in centric and and the findings are significant. In a study of 100 denture wearers eccentric positions. Balanced occlusion in complete dentures is with ages varying from 26 to 83 years, the average force in the unique, as it does not occur with natural teeth. If it occurs in natural molar and bicuspid area during mastication was 22–24 pounds. teeth, it is considered as a premature contact on the nonworking The force exerted in the incisor area dropped to nine pounds. side and is considered to be pathologic. Usually, anatomic teeth Gibbs et al. showed that the average closing force during mastication are used to arrange teeth in balanced occlusion [Figure 10a‑c]. of complete denture wearers is only 11.7 pounds, which is Nonanatomical teeth can be used with balancing ramps.[2,3] considerably below the weakest closing force of subjects with natural teeth. The comparison between natural and artificial teeth Importance shows that complete denture wearers can exert only from 10% to The concept was originally put forth to enhance the retention 15% of the force of a patient with good natural teeth. It appears, of complete dentures during mastication. However, it became therefore, that the average complete denture wearer has barely apparent that even a grain of food on the working side adequate force for the work required during mastication.[2,13,14] eliminates the balance on the nonworking side. It was aptly summarized as “enter bolus, exit balance” by Sheppard.[8] Hence, arranging modified anatomic teeth in a semi‑adjustable articulator, which can accept face bow transfer and horizontal Allen A. Brewer and Donald C. Hudson have shown that and lateral condylar guidance records from which incisal complete denture teeth do contact at times during mastication. guidance can be established for every individual patient. Based However, it will last for 17 min in a day.[9] Balance is now deemed on the interocclusal records, selective grinding is done to necessary during many excursive movements such as swallowing reduce the occlusal interferences to avoid deflective forces that saliva, closing to reseat dentures, and bruxism performed by are transmitted to the supporting structures. Then thorough patients in between meals. Hence, if the balance is not present, patient education, motivation, and regular recall will preserve the bases could shift, tip or torque on their foundations during the health of the supporting structures for the longer period.

Consequences of wearing the same complete dentures for a long period are attrition of artificial acrylic teeth and loss of occlusion. These conditions result in uneven force distribution and pathological changes in the underlying oral tissues, which will in turn results in poor patient comfort, destabilization of occlusion, inefficient masticatory function, and esthetic a problems. Ultimately, patient may not be able to wear dentures and will be diagnosed as prosthetically maladaptive.

The patients with complete dentures should follow a regular control schedule at yearly intervals so that an acceptable fit b c and stable occlusion can be maintained. Patient should be Figure 10: (a) Balanced occlusion: In centric occlusion, (b) balanced occlusion: In right lateral position, (c) balanced occlusion: In protrusive motivated to practice proper denture‑wearing habits like not position wearing dentures during the night.

204 The Journal of Indian Prosthodontic Society | Jul-Sep 2015 | Vol 15 | Issue 3 [Downloaded free from http://www.j-ips.org on Saturday, April 02, 2016, IP: 49.206.1.43]

Rangarajan, et al.: Concepts of occlusion in prosthodontics: A literature review

CONCLUSION AITBs Publishers; 2000. 3. Boucher CO. Prosthodontic Treatment for Edentulous Patients. 9th ed. Delhi: Complete edentulism not only hampers the mastication, CBS Publishers; 1990. p. 119. 4. Lang BR. Complete denture occlusion. Dent Clin North Am esthetics, but also affects the psychological well‑being of the 2004;48:641‑65, vi. patient. There has been much controversy about various concepts 5. Beck HO. Occlusion as related to complete removable prosthodontics. and the theories put forward to achieve occlusion. However, the J Prosthet Dent 1972;27:246‑62. 6. Levin B. A reevaluation of Hanau’s Laws of Articulation and the Hanau use of these principles according to the individual merits of Quint. J Prosthet Dent 1978;39:254‑8. the case, have been neglected. Each case should be thoroughly 7. Zarb GA, Bolender CL. Prosthodontic Treatment for Edentulous Patients. evaluated based on the hard and soft tissue anatomy, resorption 12th ed. New Delhi: Mosby; 2004. pattern, neuromuscular control, and the patient compliance. 8. Sheppard IM, Sheppard SM. Denture occlusion. J Prosthet Dent 1968;20:307‑18. 9. Brewer AA, Hudson DC. Application of miniaturised electronic devices to Financial support and sponsorship study of tooth contact in complete dentures, a progress report. J Prosthet Nil. Dent 1961;11:62‑72. 10. Rahn AO, Heartwell CM. Textbook of Complete Dentures. 5th ed. Conflict of interest Philadelphia: Lea and Febiger; 1993. 11. Swenson MG. Complete Dentures. 1st ed. St. Louis: C. V. Mosby Co.; 1940. There are no conflict of interest. p. 382. 12. The glossary of prosthodontic terms. J Prosthet Dent 2005;94:10‑92. REFERENCES 13. Sharry JJ. Complete Denture Prosthodontics. 3rd ed. St. Louis: Blaktison Publication; 1974. 1. Palmer CA. Gerodontic nutrition and dietary counseling for prosthodontic 14. Gibbs CH, Mahan PE, Lundeen HC, Brehnan K, Walsh EK, Holbrook WB. patients. Dent Clin North Am 2003;47:355‑71. Occlusal forces during chewing and swallowing as measured by sound 2. Winkler S. Essentials of Complete Denture Prosthodontics. 2nd ed. Delhi: transmission. J Prosthet Dent 1981;46:443‑9.

Author Help: Online submission of the manuscripts

Articles can be submitted online from http://www.journalonweb.com. For online submission, the articles should be prepared in two files (first page file and article file). Images should be submitted separately. 1) First Page File: Prepare the title page, covering letter, acknowledgement etc. using a word processor program. All information related to your identity should be included here. Use text/rtf/doc/pdf files. Do not zip the files. 2) Article File: The main text of the article, beginning with the Abstract to References (including tables) should be in this file. Do not include any informa- tion (such as acknowledgement, your names in page headers etc.) in this file. Use text/rtf/doc/pdf files. Do not zip the files. Limit the file size to 1 MB. Do not incorporate images in the file. If file size is large, graphs can be submitted separately as images, without their being incorporated in the article file. This will reduce the size of the file. 3) Images: Submit good quality color images. Each image should be less than 4096 kb (4 MB) in size. The size of the image can be reduced by decreas- ing the actual height and width of the images (keep up to about 6 inches and up to about 1800 x 1200 pixels). JPEG is the most suitable file format. The image quality should be good enough to judge the scientific value of the image. For the purpose of printing, always retain a good quality, high resolution image. This high resolution image should be sent to the editorial office at the time of sending a revised article. 4) Legends: Legends for the figures/images should be included at the end of the article file.

The Journal of Indian Prosthodontic Society | Jul-Sep 2015 | Vol 15 | Issue 3 205

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• J Indian Prosthodont Soc
• v.20(3); Jul-Sep 2020

Choosing the denture occlusion - A Systematic review

Ritika bhambhani.

Department of Prosthodontics and Crown and Bridge, Gurunanak Institute of Dental Sciences and Research, Kolkata, West Bengal, India

Shubha Joshi

1 Department of Prosthodontics and Crown and Bridge, School of Dental Sciences, Krishna Institute of Medical Sciences Deemed to be University, Karad, Satara, Maharashtra, India

Santanu Sen Roy

2 Public Health, Gurunanak Institute of Dental Sciences and Research, Kolkata, West Bengal, India

Aditi Shinghvi

3 Private Practitioner, BDS, AMRI Medical Centre, Kolkata, West Bengal, India

The aim of the study is to acquire evidence for the choice of occlusion with anatomic/modified anatomic teeth in complete denture prosthesis.

Settings and Design:

Systematic review following PRISMA guidelines.

Materials and Methods:

The study reviewed original articles on various occlusal schemes bilateral balance occlusion (BBO), lingual occlusion (LO), Canine guided occlusion (CG), posterior group function occlusion (PGFO) have been applied to the complete dentures and were analyzed for the objective or subjective or both evaluations. The data were collected in standard format with the needed information such as year of publication, type of study, occlusal schemes compared, test methodology used, sample size for experiment and control, assessment of retention, stability, and other factors which determine the quality of life and period of follow-up. The risk of bias was calculated using tools RoB2.0 and robvis. At all stages, the inclusion and exclusion of studies were discussed among the reviewers.

Statistical Analysis used:

Due to the heterogeneity in the data of the included studies no statistical analysis was used.

Of the 1896 articles screened only 17 studies were included in the systematic review. These were discussed amongst the reviewers regarding the various occlusion schemes used. The subjective and objective criteria used in the studies was tabulated separately. They were then analyzed for the risk of bias using the robvis 2 tool.

Conclusion:

No scheme is more superior to the other with the anatomic tooth forms. The use of alternative unbalanced schemes produces a similar satisfactory clinical outcome. The ridge classification also has a significant role to play in the preference for an occlusal scheme.

INTRODUCTION

The complete denture prosthesis is irreplaceable in the rehabilitation of edentulous patients. It restores oral function and maintains esthetics and patients' psychological well-being. With better medical services and a greater life span, there is an equal requirement of functional oral rehabilitation, where complete denture prosthesis too has an important role to play. This applies greatly to our developing country where implant-supported prosthesis is still away from the reach of masses. Their fabrication includes the right blend of art and science of stabilizing it against all odds of oral musculature, function, parafunction, and gravity. The basic principles to be born in mind while fabricating a complete denture include retention, support, stability, and harmony with stomatognathic system with preservation of the surrounding tissues to achieve good esthetics and function. Undesirable denture movement may result during function by unfavorable masticatory forces, but these can be minimized by multiple contacts on both working and nonworking sides during centric and all excursive mandibular movements.[ 1 ] Balanced articulation means the simultaneous anterior and posterior occlusal contact of teeth in centric and eccentric positions.[ 2 ] This concept has been applied clinically as it is assumed to dissipate the oblique forces and improve retention and stability.

However, alternatively, another approach called lingualized occlusion (LO)[ 2 , 3 , 4 ] has been advocated, where only the maxillary palatal cusps articulate with the mandibular occlusal surfaces.[ 5 , 6 ] There were reports of good acceptance of the latter too in terms of patient comfort. This makes us question the significance of the complicated procedures or rather time-consuming adjustments involved the balanced occlusion when speaking of clinical evidence. Moreover, here began a journey of various studies of different occlusal schemes and tooth forms.[ 5 , 6 ]

Various occlusal schemes other than the bilateral balanced occlusion and lingialized occlusion have also been used in denture fabrication. Schemes like Linear (Monoplane occlusion), Canine-guided occlusion, Partial group function occlusion, Buccalized occlusion have been researched upon.[ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ] The earliest mention of CGO in complete denture prosthesis was made by Gausch in 1986, where EMG (electromyographic) studies were done to explore the benefits. However, there is a need of more scientific evidence to apply these schemes in appropriate situations.[ 16 ]

Complete denture occlusion and its prospective effects on the stomatognathic system along with the quality of life of the patient hence is an area of interest. More evidence-based research is needed due to different biomechanics of conventional denture prosthesis and the subjective factors involved in it. The role of occlusion is multifactorial toward the denture success–retention, support, stability, preservation of the residual ridge and surrounding tissues/muscles, and undoubtedly the esthetics. The denture behaves different than natural teeth as it acts as one unit, where the force applied to a single denture tooth gets passed on to the whole denture. The muscle attachments and functional and parafunctional movements have their role to play in the denture success.

The other factor which has to be born in mind is the adaptability of the denture patients and also the role of tissue resiliency which is not objectively considered widely in literature. It is understood that an objective evaluation of the latter is clinically difficult and so is its role in denture settling and associated occlusal changes. That is why the denture patients were rightly termed as the denture acrobats.[ 17 ]

The balanced occlusion has been the preferred scheme for the stability of the denture, but yet questions have been raised and existed since decades regarding the clinical significance of BBO for denture success. Enter Bolus and Exit Balance' was mentioned in 1960's to emphasize the loss of occlusal balance during mastication. The deflective contacts may result in the tipping of the denture bases. But as the mastication time is much smaller than the other activities swallowing the bilateral balance would still be deisred. The aim being to minimise the deflective contacts. With use the balanced contacts originally created might be altered in the mouth but even then denture wearers can have clinical acceptance. This balance is not only dependent on the occlusal balance but also the lever balance created by the right tooth position (anteroposteriorly and mediolaterally and the occlusal height).[ 18 , 19 ] Various researches have concluded similar clinical results with other occlusal schemes, the denture teeth do not always contact, and the absence of interruptive and deflective contacts is what has been desired during function. The occlusal scheme pertaining to the above will fulfill the roles of retention and stability. Even if lost during function, the BBO may be helpful during seating during terminal arc of closure. The time and effort while preparing dentures with a balanced occlusion and the lateral forces which exist on working/nonworking sides are the areas which require evidence for the preference of BBO. Considering the Muller Devan's principle as an important parameter of success, this attempt has been made to look into more evidence related to the scheme which is clinically satisfactory and also maintains the integrity of the residual ridge and the muscles of mastication. The angle/direction and amount of forces associated to various schemes and its effect on lever balance, if known, can help choose the occlusal scheme not only by subjective preferences but also based on biomechanical principles.[ 20 , 21 ]

This systematic review has been taken up with an aim of acquiring evidence for the choice of occlusion in complete denture prosthesis. The null hypothesis being balanced and nonbalanced occlusion schemes is similar in providing the denture-related satisfaction, and no difference exists in resorption rates and long-term consequences. The authors tried to explore more of the qualitative and objective studies done in association with complete denture prosthesis.

METHODOLOGY

This review was done using the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Search policy

Literature that investigated into complete denture occlusion was searched using the predetermined search policy of PRISMA guidelines. The search policy was based on a Population, Intervention, Comparison, Outcome, and Study Design framework, and it is depicted in Table 1 . The search keywords such as complete denture occlusion, balanced occlusion, bilateral balanced occlusion, lingualised occlusion, occlusal schemes for complete dentures, canine guided occlusion, effect of tissue resilience, and denture occlusion were used. It resulted in 215 articles for “balanced occlusion,” 713 for “occlusal schemes,” 59 for “CGO in complete dentures,” 27 for “LO in CD,” 121 for “occlusal scheme in CD,” 1135 for “complete denture occlusion,” 158 for comparison in CD occlusion, and 25 for the BO in CD making a total of 2448 studies.

Population, Intervention, Comparison, Outcome, and Study Design search policy

PICOS: Population, Intervention, Comparison, Outcome, and Study Design, BBO: Bilateral balanced occlusion, LO: Lingualized occlusion, CG: Canine guidance

An electronic search of studies published till September 2019 in PubMed, Science Direct, Google Scholar, Cochrane Central Register of Controlled Trials, and EBSCOhost were included. The journals hand searched were the Journal of Prosthetic dentistry and the Journal of Indian Prosthodontic Society ; cross references and bibliography were also referred to.

Inclusion and exclusion criteria

Abstracts and full research manuscript in vivo original studies related to occlusal schemes were read thoroughly, and the following inclusion and exclusion criteria are depicted.

Inclusion criteria

• Controlled clinical trial/randomized clinical trial
• Crossover trials
• Prospective and retrospective studies
• Objective and subjective tests
• Articles in English language
• Presence of follow-up period after insertion
• Use of anatomic or modified anatomic teeth.

Exclusion criteria

• Case report and case series
• Review articles
• Animal studies
• In vitro studies
• Use of nonanatomic teeth for the denture fabrication
• Other language articles
• Implant-associated denture occlusion.

Quality assessment

Articles were read thoroughly to assess methodology, randomization, sample size, control group, blinding of participants and personnel, quality of life, retention, and stability. The assessment was first done independently, and then, discussions were done among the reviewers to include or exclude the studies and to elaborate on missing data. The Cochrane Collaboration tool was used as an aid. Risk of bias was estimated as low, medium, or high based on the Cochrane risk of bias tool RoB2.0 and robvis ( Chart 3 shows the use of robvis).[ 22 ]

Risk of bias domain

Data extraction

The data information from published articles was collected in the needed format to include the information such as year of publication, type of study, type of occlusal schemes compared, test methodology used, sample size, assessment of retention, stability, and other factors of denture quality assessment and period of follow-up[ 15 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ] [ Table 2 ].

The Included studies of the systematic review

The steps of literature search were mainly identification, screening, eligibility, and inclusion or exclusion as suitable. Both reviewers did an independent search, and conclusions were reached by mutual discussions on the selected articles [ Table 3 ].

Based on the search policy

Most of the studies included have been crossover studies, and these trials decrease the intersubject response variations due to reasons such as masticatory strength and unrealistic expectations. Most of the included crossover studies have used the same denture base which would omit the duplication errors (Khamis and Hussein method). At the same time, there exists a carryover effect with no washout period, which may result in reporting bias from the patients' response.[ 2 , 24 , 35 ] Some studies used single blinding when examiners were also involved in the denture construction whereas some studies were double blinded.[ 15 , 31 ]

The patient satisfaction was considered as the primary outcome to be tested, and the methods used have been subjective questionnaire formats related to denture-related satisfaction variables, Visual Analog Scale, Likert scale, oral health-related quality of life assessed using the Oral Health Impact Profile (OHIP), OHIP-edentulous adults, German Society for Dentistry and Oral Medicine for Functional and Diagnostic Therapy, and other rating formats [ Table 2 ]. Tests for retention and stability were based on examiner skills[ 35 ] or Kapur index.[ 36 ]

Objective analyses have been performed for the masticatory forces, masticatory efficiency, and the stress and strain on the ridge, and EMG studies for the muscle activity have been done. Masticatory function was assessed by food particle size estimation using sieve method, colorimetric determination, optical scanning, biting force, or weight loss of viscoelastic food. Dentures with CGO were preferred more for certain food products such as carrots and meat. BO and LO were found to reduce selective food avoidance and physical disability aspects of patient satisfaction. More dislodging forces in BBO could cause patients to avoid some foods causing an unpleasant eating experience.[ 25 ] No difference in the masticatory efficiency was reported among various schemes,[ 17 , 22 , 25 ] and on the contrary, the efficiency is more ridge dependent.[ 24 , 25 ] In poor residual ridge conditions, LO was preferred by patients for acceptable stability and masticatory efficiency and retention. It allows modifications to adapt to various ridge types, elimination of lateral interferences, and settling without cuspal interferences.[ 11 , 31 ] LO was also associated with a better lever balance and hence more controlled forces.[ 14 ]

MO has been reported for the requirement of more adjustment time and more chairside corrections; it compromises on esthetics and masticatory efficiency with no special benefits. Anatomical tooth forms were found more efficient for chewing efficiency and denture adaptation; hence, the present review explored the latter and schemes with modified anatomic teeth.[ 1 , 11 ] An in vitro study on resilient edentulous jaw simulator was carried out for pressure analysis of various occlusal schemes to check for pressure on nonworking side by unilateral chewing. Pressure sensors and multichannel electronic strain indicators were used to check for pressure on the ridge under BBO, LO, and MO. The pressure in MO was found the least and almost similar in BO and LO.[ 37 ] Results were found statistically equivalent for BBO and LO. Being an in vitro study, this was excluded.

Anterior tooth group function and CGO have been mentioned for the efficiency for chewing. The points to be explored further are, the effects on denture retention and transfer of occlusal stresses. Some researchers have named these as 'Lateral occlusal guidance studies' where canine or premolar guided occluion is preferred to bilateral balance.[ 38 ] CGO was preferred for esthetics, phonetics, masticatory function, and retention in a crossover study with 50 subjects (10 dropouts) where all subjects preferred CGO, but a greater adjustment time was involved.[ 31 , 39 ] In another study,[ 11 ] similar results were concluded. Either a separate denture was fabricated or only the occlusal scheme was modified by alteration of canines. The CGO is the preferred scheme in dentulous patients for the well-known reason of discussion of posterior teeth during lateral movements, better esthetics, and lesser and easier fabrication time. A reduced muscle activity was explored, with no negative influence on lateral stability or higher resorption rates.

Little difference was found clinically among various occlusal schemes, so if the time taken for BBO is taken into consideration, the application of the same on a regular clinical basis is questionable. LO has been proved equally accepted but has not been taken as a control group in any of the comparisons. Scientific data for resorption patterns were not found in any of the studies, and a trend of subject dropouts might exist in prospective studies. A trend toward studies for the CGO has been comparatively more in the near past, and related literature was found only after the year 2000 [ Chart 1 ]. The studies related to CGO are crossover trials which make them more valued, but none of the comparisons have been made with LO dentures. LO can provide the same freedom of movement as in neutrocentric or MO, even in cases of weak muscle engrams and with a better functional efficiency. The discrepancies in studies' results might occur due to certain factors like- clinician's technique or interoperator variability, tooth material and form selected, and various patient factors (ridge type, resilience and unrealistic or realistic expectations.). More scientific evidence for preference of certain schemes in specific situations and their long-term effect on ridge resorption would be beneficial. Studies based on finite element analysis for complete denture can be explored and have scope for future.[ 40 ]

Timeline of clinical trials associated with selected occlusal schemes

CONCLUSIONS

Hypothesis was found partially correct that all schemes, if wisely used, can bring out good clinical results. No scheme is more superior to the other when using the anatomic tooth forms [ Chart 2 ]. The part of hypothesis regarding the resorptive rates is difficult to be supported with enough evidence as there are no prospective studies with the different occlusal schemes. There is scope for more evidence-based research for the preferred occlusal scheme in different ridge relations and comparative trials of CGO with LO. Balanced occlusion is one of the preferred choices for occlusal schemes but not for all the ridges. Lingualized occlusion can be helpful in resorbed ridges for the masticatory efficiency and even in providing bilateral balance. CGO is the most preferred occlusion scheme for dentulous situations and needs more evidence-based research related to its effects on denture stability.

Representation of subjects, preference for various occlusal schemes

The complete denture prosthodontics is the most difficult and skill requiring area to bring out the best rehabilitation in an edentulous patient. The wise choice of varied parameters is sure to result in clinical success.

Financial support and sponsorship

Conflicts of interest.

There are no conflicts of interest.

Acknowledgment

We would like to thank all working toward an evidence-based dentistry.