Cone-beam tomography assessment of condylar position discrepancy between centric relation and maximal intercuspation

Is the positioning guide mandatory for the virtual planning of orthognathic surgery? A randomized double-blind trial

OBJECTIVES

The aim of this study is to verify the positioning of the condyles in computed tomography (CT) scans of skeletal Class II and Class III patients in virtual surgical planning before orthognathic surgery. The secondary aim is to determine whether occlusal devices are mandatory for performing a CT examination.

MATERIALS AND METHODS

In this retrospective randomized double-blind study, 42 CT scans were evaluated from patients who had undergone to orthognathic surgery at the University Hospital of the University of São Paulo. Male and female patients between the ages of 25 and 40 were included. The sample consisted of skeletal Class II and III patients. The CTs were randomly selected into centric relation (CR) and maximal intercuspal position (MI). Statistical analysis was performed with R Statistical Package and was considered significant in the case of p <0.0001.

RESULTS

A total of 504 measurements were carried out in 42 patients. Three joint spaces on each side were used. No statistically significant difference between the inter- and intraobservers was found for CR and MI. Some scores were performed to avoid the risk of gender bias.

CONCLUSIONS

No statistically significant value was found between patients in CR and MI after mandibular manipulation. The use of a positioning guide to perform a CT scan prior to virtual planning is not absolutely necessary.

Centric relation: A needed reference position

PURPOSE

Centric Relation (CR) is a universally recognized term and an acceptable reference position with a long history of success. The problem is that there is little consensus as to its definition or the method of recording it, and this has created an uprising to abolish it.

METHODS

A review of pertinent literature related to its definition, method of recording, anatomic considerations and long-standing principles was conducted.

RESULTS

CR is an established term but there are valid concerns over its definition and method of recording. There is consensus on using it as a restorative position in a patient in need of full arch reconstruction and there is no substantive clinical research to contradict this. If a clinician decides to use a different position, it should have a different name.

CONCLUSIONS

CR is a reproducible reference position that can be utilized for diagnostic and restorative dental procedures with substantial scientific evidence to support that premise. There are numerous well documented techniques, all of which are intermaxillary, that can replicate the position. There is little scientific evidence to support a premise as to where the exact position of the condyle should be in relation to the fossa. This article is protected by copyright. All rights reserved.

Assessment of the Morphology and Degenerative Changes in the Temporomandibular Joint Using CBCT according to the Orthodontic Approach: A Scoping Review

Background. Available knowledge about disorders of temporomandibular joint structures and their association with orthodontic variables are still lacking. Objectives. This article is aimed at to identifying studies and presenting current information on the relationship between morphology diversity and the occurrence of degenerative changes in structures of the temporomandibular joint (TMJ) assessed by cone-beam computed tomography (CBCT) in the context of craniofacial morphology and malocclusion. Search Methods. The review was conducted by analyzing the PubMed (including Medline), Cochrane Library, Web of Science, and Scopus electronic databases up to November 2021 using two different comprehensive search strategies based on keywords as well as additional manual searches. Eligibility Criteria. Selection of the literature was carried out according to the PRISMA-ScR checklist. Methodological quality of the selected studies was evaluated using JBI Critical Appraisal Tool. Results. The electronic databases search revealed 3331 records. After applying the eligibility criteria and JBI assessment, a total of 33 studies were extracted and selected to the study. The review was divided into 4 parts, in which the following correlations were assessed in terms of orthodontic variables: TMJ degenerative changes, joint space and condylar position, condylar shape, TMJ articular eminence, and fossa. Conclusions. Skeletal and dental class II malocclusion with a retrognathic mandible, a hypodivergent skeletal pattern with a steep mandibular plane, and significant lateral mandibular displacement can be risk factors for developing radiographically detectable degenerative changes. Patients with skeletal and dental class III malocclusion as well as a hyperdivergent skeletal pattern may be at greater risk of TMD occurrence compared with other groups. Further studies are necessary to clarify the relationship between the position of the condylar processes and the presence of degenerative changes in the temporomandibular joints among orthodontic patients.

The Relationship Between Centric Occlusion and The Maximal Intercuspal Position and Their Use as Treatment Positions for Complete Mouth Rehabilitation: Best Evidence Consensus Statement

PURPOSE

The purpose of this Best Evidence Consensus Statement was to evaluate the existing literature relative to two focus questions: How often does centric occlusion coincide with maximal intercuspal position in dentate and partially dentate populations?; and should centric occlusion or maximal intercuspal positions be equivalent for dentate and partially dentate patients undergoing complete mouth rehabilitation?

MATERIALS AND METHODS

Keywords used in the initial search were: intercuspal position, centric occlusion, centric relation, maximal intercuspal position, prosthodontic rehabilitation, and occlusion. The search was then limited to Systematic Reviews, Randomized Controlled Studies, Meta-analyses and Clinical Trials.

RESULTS

The initial search strategy related to the selected search terms resulted in more than 15,000 articles. When the subsequent search was limited to Systematic Reviews, Randomized Controlled Studies, and Meta-Analysis and Clinical Trials, 313 articles were selected for further analysis.

CONCLUSIONS

Review of the literature reveals that most dentate and partially dentate patients do not have coincident centric occlusion and maximal intercuspal position. There is support for coincidence between centric occlusion and maximal intercuspal position as the preferred occlusal relationship in complete mouth rehabilitations. The literature does not report conclusive evidence of adverse prosthodontic outcomes with complete rehabilitations in centric occlusion or maximal intercuspal position in a healthy population. However, there is support for an association between centric occlusion-maximal intercuspal position discrepancies and occlusal instability as well as temporomandibular joint disorders. Hence, it is concluded that partially and completely dentate patients requiring complete mouth rehabilitation should be restored in centric occlusion.

Angle's Classification-A Prosthodontic Consideration: Best Evidence Consensus Statement

PURPOSE

This Best Evidence Consensus Statement evaluated the existing Angle's classification clinical literature to determine if the Angle's classification as historically determined in maximum intercuspal position (MIP) with hand held casts is coincident with the centric occlusion (CO) determined Angle's classification. In addition, it explored the value of using Angle's classification for edentulous patients MATERIALS AND METHODS: The search strategy was related to the focus questions and limited to Meta-analyses, Systematic Reviews (SR), Randomized Controlled Trials (RCT) and Clinical Trials. Searches were completed using the term Angle's classification and Boolean Modifiers (AND) with the key terms: dental occlusion, dental occlusion centric, centric occlusion, centric relation, maximal intercuspation, MIP, intercuspal position, and edentulous patient, retrognathia, determination, and prognathia. Additional related articles were culled from the reference lists in the articles found in the PubMed searches.

RESULTS

The search identified 494 articles related to the selected terminology. Titles were reviewed and selected if related to the focus questions for further review. Seven papers could be identified that addressed the specifics of the questions.

CONCLUSIONS

There is evidence that the Angle's classification for many patients will change when recorded in CO compared to the historical MIP determination/definition. A different Angle's classification recorded in CO is potentially a significant diagnostic finding for patients needing complete mouth rehabilitation. The current definitions of Angle's Classification are not useful in the management of edentulous patients.

Evaluation of the condylar position in younger and older adults with or without temporomandibular symptoms by using cone beam computed tomography

STATEMENT OF PROBLEM

Recent studies in young adults have questioned the influence of discrepancies between central and maximal intercuspal positions in temporomandibular disorders (TMDs). However, whether this finding was because this type of etiologic agent requires time for the development of changes in the condylar position is unclear.

PURPOSE

The purpose of this clinical study was to use cone beam computed tomography (CBCT) to evaluate the presence or absence of discrepancies between the centric relation (CR) and maximum intercuspation (MI) in younger and older adults in populations with or without TMDs.

MATERIAL AND METHODS

The sample was composed of 80 volunteers, 40 younger individuals aged 18 to 25 years (27 women and 13 men), half with and half without TMD symptoms, and 40 older participants aged 35 to 50 years (30 women and 10 men), half with and half without TMD symptoms. The TMD symptoms were diagnosed by using the diagnostic (standard) criteria for TMD research (RDC/TMD). Two CBCT scans were performed on each participant, one in MI and another in CR. Measurements of the joint space were performed in coronal and sagittal cuts of the temporomandibular joints, and the collected data were statistically analyzed by using the Mann-Whitney U test (α=.05).

RESULTS

No significant differences were found when the CR and MI positions and the presence or absence of TMD symptoms were compared in the younger and older groups. However, when the younger and older groups were compared, significant differences were found in all measures used in this study.

CONCLUSIONS

The condyle and mandibular fossa do not seem to be influenced by the CR or MI positions or by the presence or absence of TMD symptoms, but age seems to lead to a quantitative increase in the relationship between these structures.

Centric relation-intercuspal position discrepancy and its relationship with temporomandibular disorders. A systematic review

OBJECTIVE

The objective of this study is to assess the relationship between centric relation-intercuspal position discrepancy (CR-ICP discrepancy) and temporomandibular disorders (TMDs), by systematically reviewing the literature.

MATERIALS AND METHODS

A systematic research was performed between 1960 and 2016 based on electronic databases: PubMed, Cochrane Library, Medline, Embase, Scopus, EBSCOhost, BIREME, Lilacs and Scielo, including all languages. Analytical observational clinical studies were identified. Two independent authors selected the articles. PICO format was used to analyze the studies. The Newcastle-Ottawa Scale (NOS) was used to verify the quality of the evidence.

RESULTS

Four hundred and sixty-seven potentially eligible articles were identified. Twenty studies were analyzed, being grouped according to intervention in studies in orthodontic patients (n = 3) and studies in subjects without intervention (n = 17). Quality of evidence was low, with an average score of 3.36 according to Newcastle-Ottawa Scale. In most studies, the presence of CR-ICP discrepancy is associated with the presence of muscle (pain) and joint disorders (noise, disc displacement, pain, crepitus, osteoarthritis and osteoarthrosis). However, the lack of consistency of the results reported reduces the validity of the studies making it impossible to draw any definite conclusions.

CONCLUSIONS

Because of the heterogeneity of the design and methodology and the low quality of the articles reviewed, it is not possible to establish an association between CR-ICP discrepancy and TMD. The consequence of CR-ICP discrepancy on the presence of TMD requires further research, well-defined and validated diagnostic criteria and rigorous scientific methodologies. Longitudinal studies are needed to identify CR-ICP discrepancy as a possible risk factor for the presence of TMD.

Centric slide in different Angle's classes of occlusion

The purpose of this study was to test the possible differences in centric slide values between different Angle's classes of occlusion. The study included 98 participants divided into four groups: Angle's class I, Angle's class II, subdivision 1, Angle's class II, subdivision 2 and Angle's class III. All recordings were obtained using an ultrasound jaw tracking device with six degrees of freedom. The distance between the maximum intercuspation (reference position) and the centric occlusion was recorded at the condylar level. Anteroposterior, superoinferior and transversal distance of the centric slide were calculated for each participant, and the data were statistically analyzed (analysis of variance and Newman-Keuls post hoc test). No statistically significant difference was found in the anteroposterior and transversal distance of the centric slide between tested groups, while Angle's class II, subdivision 2 showed smaller vertical amount of the centric slide compared to Angle's class I and class II, subdivision 1. None of the 98 participants showed coincidence of centric occlusion and maximum intercuspation. Our results suggest that coincidence of the maximum intercuspation with the centric occlusion should not be expected. Smaller extent of the vertical distance of the centric slide could be morphological and a functional expression characteristic of the Angle's class II, subdivision 2.

Coronal joint spaces of the Temporomandibular joint: Systematic review and meta-analysis

Introduction

The joint space measurements of the temporomandibular joint have been used to determine the condyle position variation. Therefore, the aim of this study is to perform a systematic review and meta-analysis on the coronal joint spaces measurements of the temporomandibular joint.

Material and Methods

An electronic database search was performed with the terms “condylar position”; “joint space”AND”TMJ”. Inclusionary criteria included: tomographic 3D imaging of the TMJ, presentation of at least two joint space measurements on the coronal plane. Exclusionary criteria were: mandibular fractures, animal studies, surgery, presence of genetic or chronic diseases, case reports, opinion or debate articles or unpublished material. The risk of bias of each study was judged as high, moderate or low according to the “Cochrane risk of bias tool”. The values used in the meta-analysis were the medial, superior and lateral joint space measurements and their differences between the right and left joint.

Results

From the initial search 2706 articles were retrieved. After excluding the duplicates and all the studies that did not match the eligibility criteria 4 articles classified for final review. All the retrieved articles were judged as low level of evidence. All of the reviewed studies were included in the meta-analysis concluding that the mean coronal joint space values were: medial joint space 2.94 mm, superior 2.55 mm and lateral 2.16 mm.

Conclusions

the analysis also showed high levels of heterogeneity. Right and left comparison did not show statistically significant differences.

Key words:Temporomandibular joint, systematic review, meta-analysis.

Identification of occlusal prematurity by clinical examination and cone-beam computed tomography

The aim of this study was to evaluate the ability to identify occlusal prematurity by images from paraxial slices of cone-beam computed tomography (CBCT). For such purpose, a pilot study was performed in which 16 asymptomatic young patients were subjected to a clinical examination, including a careful occlusal analysis and then individual deprogrammer devices (“Lucia's JIG”) were fabricated. Premature contacts were clinically identified in centric relation (CR) for each patient by jaw manipulation and interocclusal marking with articulating paper (Accufilm). Subsequently, these devices were adjusted in CR and used during the tomographic exams in such a way that CBCT in CR could be obtained. After routine processing, the images were analyzed in order to identify occlusal prematurity on the displayed images by 30 professionals divided according to areas of activity (occlusion specialist, general practitioner and radiologist; n=10 per area) and time of professional experience (less than 5, between 5 and 10, and over 10 years). By comparing the premature contacts identified in the clinical analysis and CBCT images, an agreement index between these two variables was calculated. Data were analyzed statistically by ANOVA and Scott-Knott test (α=0.05). The results showed that the identification of occlusal prematurity by paraxial CBCT slices was proven to be a method of average reliability.