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Lingualized Occlusion: An Occlusal Solution for Edentulous Patients

Occlusion is a critical component in any aspect of prosthodontic care including that related to the treatment of dentate, partially dentate, or edentulous patients. When complete dentures are fabricated for an edentulous patient, occlusion has a considerable influence on the outcome of treatment. Due to the relative simplicity involved in development of a lingualized occlusal scheme by dental laboratory technicians, this approach has gained favor among practitioners who are able to evaluate and/or correct tooth arrangements for complete dentures. This article will highlight the influences of a lingualized tooth arrangement in complete denture occlusion as it relates to improving edentulous patients’ function and quality of life; it will also demonstrate a predictable approach to achieving lingualized occlusion in complete denture prosthodontics. 

Critical to the success of any intraoral prosthesis or dental restoration is occlusion, a concept that has been the subject of numerous opinions and investigations reflective of the various definitions which vary from practitioner to practitioner. Occlusion is not defined solely as the nature of occlusal contact between opposing teeth but more broadly refers to the dynamic relationship between the teeth, the neuromusculature system, the temporomandibular joints (TMJs), and their interactive relationship in the craniofacial environment.1 This relationship has been described by numerous authors2-4 who have cited the importance of occlusion related to the long-term function of a prosthesis or restoration and the overall health of the patient.

Achieving proper occlusion for a patient is as fundamental to success as function or esthetics, and is essential when the clinician provides complete dentures for an edentulous patient. As the global population aged greater than 65 years old is projected to increase,5 and given that substantial tooth loss is common among such elderly patients, complete denture therapy will continue to grow in importance. Edentulous patients are adversely affected by the loss of their teeth and concomitant ridge resorption, experiencing inadequate fit of their prostheses, compromised intraoral comfort, health, esthetics, and ultimately, function.1,6

Consequently, to restore these patients to a better quality of life remains a fundamental treatment goal for the contemporary practitioner.

Facing the growing edentulous patient population, the ability of the dental practitioner to deliver functional, esthetic complete dentures in proper occlusion represents an opportunity to build a patient base for one’s dental practice, providing professional satisfaction that meets the objectives of both clinician and patient as well as builds practice revenues. This article describes the manner by which providing complete dentures—meeting a patient’s functional needs with tooth arrangement aligned in lingualized occlusion— can provide a predictable, time-effective method of providing appropriate prosthodontic care for this segment of the patient population.

 

Musculoskeletal Components

The muscles of mastication, as controlled by the central nervous system (CNS), influence mandibular jaw movements and are involved with any occlusal scheme, evidenced in the dentate patient population. The masseters, pterygoids and temporalis muscles are principle among the muscles of mastication and their function influences the clinician’s selection of a given occlusion (Figure 1). Consequently, the clinician must consider function of the muscles of mastication during the denture tooth arrangement to ensure the patient’s full range of motion during speech, deglutition, mastication, and potential parafunctional movements. Since masticatory forces generated by the muscles of mastication in a patient with complete dentures is considerably less than that of a fully dentate patient,7 the clinician must prescribe the appropriate denture tooth arrangement in dentures in addition to the tooth shade and form to restore function in the edentulous patient.

 

Lingualized Occlusion

The clinician prescribes replacement and alignment of the denture tooth arrangement in order to distribute occlusal forces across the remaining intraoral supporting structures, with the ultimate goal to restore the patient to function.1 By prescribing the use of a lingualized occlusion to accomplish such a goal for patients to function with complete dentures, the maxillary lingual cusps fit along the central fossa of the mandibular occlusal surfaces, into the deepest possible contact with the opposing tooth mold (Figures 2-3-4). By definition,2 setting denture teeth into a lingualized occlusion requires the maxillary lingual cusps of the denture teeth to serve as principle functional elements and the main supporting cusps in function with occlusal surfaces of the mandibular teeth. The maxillary lingual cusps of the denture teeth can be arranged to oppose either mandibular zero-degree or shallow-cusped denture teeth (Figures 5-6-7). The denture tooth arrangement for complete dentures can be set to achieve either a balanced or non-balanced occlusal arrangement, prescribed by the clinician according to the needs of the patient.2

The lingualized occlusion concept has been described as an occlusal scheme that is applicable for various edentulous patient situations and one that fulfills multiple needs as the “middle of the occlusal spectrum”.2 This approach to occlusion in complete denture therapy encompasses several of the perceived benefits of an anatomic occlusion (eg, esthetics, prosthesis stability during parafunctional movements) in addition to incorporating some of the advantages of the neutrocentric concept of denture occlusion such as a simpler technique and potential benefit of decreased lateral forces, without many of the limitations that can accompany these two ranges of denture tooth occlusal schemes.2 In addition to providing an esthetic advantage,7 the lingualized occlusion denture tooth arrangement in complete denture treatment is purported to provide better food bolus penetration and potentially to decrease the vertical forces placed on the residual alveolar ridges of the patient.2,7

In function, complete dentures with a lingualized occlusal concept provide “mortar and pestle” action typified by the neutrocentric approach as well as include a type of shearing action found in complete dentures following an anatomic occlusal concept. Not only does the concept of lingualized occlusion satisfy the needs of the edentulous patient, but also fulfills the dentist’s philosophy of complete denture occlusion as well. Accordingly, it has grown in popularity in practice and educational settings, as well as dental laboratory facilities, since it can be prescribed to address the varied patient scenarios.

 

Clinical Procedure

The jaw relation records necessary in the fabrication of complete dentures are important but can be difficult to obtain in some patients. For those patients in whom uncertainty exists with occlusal registration and reproducibility of the jaw relation record, use of lingualized occlusion may allow for greater flexibility on the clinician’s part when recording the jaw relation of edentulous patients. This is due, in part, to the greater freedom of movement around maximum intercuspation position for edentulous patients provided in the lingualized occlusal concept.2,8 Using the Prosthodontic Diagnostic Index for Edentulous Patient Classification developed by the American College of Prosthodontists,9 Class I and Class II types of edentulous patients which include patients who show clinical evidence of some loss of bone but with most anatomic landmarks present, can often be treated using the described procedure. Edentulous Patients categorized as Class III and Class IV patients should be handled by experienced clinicians since these categories of patients can include additional factors, anatomical and other types of factors, regarded as requiring advanced and/or distinct procedures to meet patient needs beyond basic denture fabrication techniques.

Throughout the fabrication procedures, the clinician should strive for the best anatomical and functional fit possible for the patient. During an initial patient appointment, a full-arch edentulous tray of the clinician’s choice is used to make the preliminary impression for a diagnostic cast. For patients in the Prosthodontic Diagnostic Indices of Edentulous

Patient Class I or Class II, a well-designed full-arch edentulous tray can be used with a medium- or high-viscosity impression material to capture the full extent of anatomic features of the patient’s edentulous arch. During this process, the clinician must be careful to perform muscle trimming as the material reaches final set so the border-molding procedures ensure that the final prosthesis encompasses all functional borders and ideally conforms to the patient’s intraoral anatomy.

At a subsequent appointment, the occlusal vertical dimension (OVD), plane of occlusion, and phonetic requirements are established to determine where the denture teeth will be positioned for the denture and how the prosthesis will be fabricated to meet extraoral esthetic considerations including but not limited to lip support and overall extraoral support in the lower third of facial balance.10 Based on the esthetic proportions and related functional, esthetic, and phonetic parameters, the tooth mould and shade will be selected and prescribed to the dental laboratory technician with the articulated master casts, jaw relation records, and related diagnostic information identified on the record bases and occlusion rims to permit ideal communication in fabrication of the prostheses.

Once the waxed trial denture is fabricated in the dental laboratory and returned to the clinician, the waxed trial denture is tried-in to permit evaluation of the patient’s occlusion as well as phonetics, esthetics, and comfort (Figure 8). It is often beneficial for the patient to be accompanied by a family member to provide an additional perspective as to his or her appearance with the trial prostheses. Any adjustments required at this time can be noted and communicated to the laboratory technician or, in some instances, simple tooth rearrangement can be performed chairside for immediate patient feedback and clinical verification of occlusal relations. Complete dentures set in lingualized occlusion are often easier to adjust than cross-tooth-cross-arch fullybalanced anatomic occlusion.2

At the final insertion appointment, the complete dentures are fitted to each arch individually to insure appropriate anatomic adaptation. After following a careful process utilizing a pressure-indicating disclosing material to adjust and fit the prostheses intraorally, the dentures are seated. The patient’s protrusive, lateral excursive mandibular movements, and related facial expression movements are performed by the clinician to ensure the prosthesis has a proper fit both to the residual alveolar supporting tissues, as well as the opposing denture occlusion (Figures 9 and 10). A clinical remount procedure is performed with an articulator using jaw relation records for analysis of the denture in centric relation and eccentric simulated movements. Any necessary occlusal adjustments are performed and the patient is reappointed for a follow-up evaluation.

 

Prosthesis Postinsertion Maintenance

The patient should be recalled periodically, minimum of an annual follow-up, to permit evaluation of the prostheses and the overall health of the intraoral structures. Evaluation and examination of the integrity and fit of the prostheses are necessary to avoid adding complicating factors to patients who have already become edentulous and compromised functionally. As in the clinical wax trial denture appointment, the complete dentures can be remounted for proper occlusal evaluation and examined for wear. Also, the prostheses should be cleaned with a professional strength cleaner in an ultrasonic system and careful review and proper oral hygiene maintenance procedures should be reviewed with the patient.

 

Conclusion

Utilizing esthetic, durable denture base resin materials and selecting wear-resistant denture teeth in conjunction with predictable occlusal schemes, practitioners are able to improve the quality of life for their edentulous patients. Removable prosthodontics in patient care can be instrumental in rehabilitating patients to maximize proper nutrition whenever possible, eliminate social stigmata, and improve their self-esteem. Complete denture therapy using a lingualized occlusal concept can be applied to multiple clinical situations and incorporates many of the advantages afforded by other occlusal schemes. The lingualized occlusal concept represents a simple and predictable approach as a valuable addition to the practitioner’s prosthodontic armamentarium.

 

*Professor and Chair, Department of Prosthodontics, University of Texas Health Science Center at San Antonio, San Antonio, Texas. Diplomate, American Board of Prosthodontics.

†Assistant Professor, Department of General Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas. Diplomate, American Board of Prosthodontics.

 

References

 

  1. McNeil C. Fundamental treatment goals. In: McNeil C, ed. Science and Practice of Occlusion. Carol Stream, IL;Quintessence Publishing, 1997:306-322.
  2. Parr GR, Loft GH. The occlusal spectrum and complete dentures. Compend Contin Educ Dent 1982;3(4):241-251.
  3. The Glossary of Prosthodontic Terms. 8th ed. CV Mosby, St. Louis, MO; 2005:57.
  4. Dawson PE. Evaluation, Diagnosis, and Treatment of Occlusal Problems, 2nd ed. St. Louis, MO; Mosby, 1989:14-17.
  5. Jones JA, Orner MB, Spiro A, Kressin NR. Tooth loss and dentures: Patient’s perspectives. International Dental J 2003;53:327-334.
  6. McGill Consensus Statement on Overdentures. Int J Prosthodont 2002;15(4):413-414.
  7. Becker CM, Swoope CC, et al. Lingualized occlusion for removable prosthodontics. J Prosthet Dent 1977;38:601-608.
  8. Zarb GA, Bolender CL, Carlsson GE. Boucher’s Prosthodontic Treatment for Edentulous Patients. 11th ed. Mosby, St. Louis, MO: 1997.
  9. McGarry TJ, Nimmo A, Skiba JF, et al. Classification system for complete edentulism. J Prosthodontics 2002;11(3):181-193.
  10. Ricketts RM. Divine proportion. In: Goldstein RE, ed. Esthetics In Dentistry. BC Decker, Hamilton, Ontario,1998:187-206.

 

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