Condylar repositioning in mandibular retrusion

Quantitative evaluation of edentulous maxillomandibular relationship record using diagnostic complete dentures fabricated by CAD and 3D printing

PURPOSE

The present study aimed to quantitatively evaluate the accuracy of the edentulous maxillomandibular relationship record for diagnostic complete dentures fabricated using computer-aided design (CAD) and three-dimensional (3D) printing.

METHODS

Six edentulous patients were enrolled. The maxillomandibular relationship obtained from diagnostic complete dentures (DiaCD test group), that obtained from complete dentures with artificial teeth in the intercuspal position (CD control group), and the centric relationship acquired by gothic arch tracing (CR standard group) were recorded, and 3D surface scanning was performed on these records. Using the CR standard group as a reference, the DiaCD test and CD control group displacements were measured in the horizontal antero-posterior, horizontal right-and-left, and vertical directions. The displacements for the DiaCD test group were compared with those for the CD control group using the Wilcoxon matched-pairs signed rank test.

RESULTS

In terms of centric relationship, the 95% confidence interval of displacement in the horizontal antero-posterior direction was (0.54-1.89) mm in the DiaCD test group and (0.32-1.34) mm in the CD control group. The inter-group difference was significant (P = 0.03).

CONCLUSION

It is feasible to record the edentulous maxillomandibular relationship using diagnostic complete dentures fabricated by CAD/3D printing, but the protrusion of edentulous patients should not be neglected.

Comparative analysis between mandibular positions in centric relation and maximum intercuspation by cone beam computed tomography (CONE-BEAM)

This research consisted of a quantitative assessment, and aimed to measure the possible discrepancies between the maxillomandibular positions for centric relation (CR) and maximum intercuspation (MI), using computed tomography volumetric cone beam (cone beam method). The sample of the study consisted of 10 asymptomatic young adult patients divided into two types of standard occlusion: normal occlusion and Angle Class I occlusion. In order to obtain the centric relation, a JIG device and mandible manipulation were used to deprogram the habitual conditions of the jaw. The evaluations were conducted in both frontal and lateral tomographic images, showing the condyle/articular fossa relation. The images were processed in the software included in the NewTom 3G device (QR NNT software version 2.00), and 8 tomographic images were obtained per patient, four laterally and four frontally exhibiting the TMA’s (in CR and MI, on both sides, right and left). By means of tools included in another software, linear and angular measurements were performed and statistically analyzed by student t test. According to the methodology and the analysis performed in asymptomatic patients, it was not possible to detect statistically significant differences between the positions of centric relation and maximum intercuspation. However, the resources of cone beam tomography are of extreme relevance to the completion of further studies that use heterogeneous groups of samples in order to compare the results.

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

This article addresses the historical perspective of the gnathological influence upon the concepts of occlusion for fixed prosthodontics. A critical assessment and subsequent scientific validation of occlusal theories require an understanding of their evolution in the formative years and the subsequent development of effective models for clinical practice. While gnathological concepts offer a structured methodology for prosthodontic procedures, further research is needed to corroborate current occlusal treatment approaches. This review focuses on the "classic" fixed prosthodontic literature and the currently available scientific literature involving fixed prosthodontic dentate occlusion and gnathology. A MEDLINE search was performed to identify English-language peer-reviewed publications spanning the last 56 years, along with an extensive hand search for years prior. Electronic searches of the literature were performed in MEDLINE using the key words: case series, clinical trials, cohort studies, fixed partial denture occlusion, dental occlusion, dental occlusion research, centric relation, incisal guidance, maximal intercuspation, occlusal vertical dimension, and occlusion, in various combinations to obtain potential references for review. A total of 10,382 English-language nonduplicate titles were obtained for 1950-2006 for the key words "dental occlusion." Other key word searches produced smaller numbers of articles, many of which were duplicates due to multiple searches and were subsequently eliminated. Manual hand searching of the MEDLINE reference list and other journals of interest was performed to identify any articles missed in the original search. Articles were included for review if they contained emerging occlusal theories, new technologies, or occlusal studies that included multiple subjects in contrast to case reports.

Maxillomandibular relationship philosophies for prosthodontic treatment: A survey of dental educators

STATEMENT OF PROBLEM

A variety of treatment philosophies persist concerning the need for coincidence of centric occlusion (CO) and maximum intercuspation (MI) in prosthodontic restoration; however, no consensus exists.

PURPOSE

The purpose of this study was to determine the philosophies of dental educators throughout the United States at both the predoctoral and postdoctoral levels and to compare their attitudes toward desirable maxillomandibular relationships in defined clinical situations.

MATERIAL AND METHODS

A survey was constructed with 5 clinical scenarios presented describing patients with a difference between maximum intercuspation and centric occlusion. The survey was mailed to 171 dentists involved in either predoctoral or postdoctoral dental programs in the United States; including 56 dental schools; the Army, Navy, and Air Force postdoctoral programs; 8 Department of Veterans Affairs postdoctoral programs; and 7 hospital-based programs. Descriptive statistics of the responses were provided. Chi-squared (alpha=.05) and Fisher's exact test analyses (alpha=.05) comparing predoctoral and postdoctoral program responses for each question were performed.

RESULTS

Forty-three predoctoral dental school program responses were received. Forty-one postdoctoral program directors, including the dental school-based programs, 3 armed service branches, 2 Veterans Administration programs, and 1 hospital-based program responded to the survey. Fifteen respondents indicated that they represented both predoctoral and postdoctoral programs, and these data were deleted from the sample. Summarized results for each question reflect on whether the clinicians philosophically believed patients were better off with the elimination of an existing occlusal interference between MI and CO or not. There was no statistically significant difference seen between the predoctoral and postdoctoral responses.

CONCLUSION

The controversy regarding the preferred mandibular position for treatment of dentulous and partially edentulous patients continues among dental educators at both the predoctoral and postdoctoral levels in the United States.