Evaluation of missing-tooth effect on articular eminence inclination of temporomandibular joint

Characteristics of the Occlusal Plane Associated with Unilateral and Bilateral Articular Eminence Inclination: A Cross-Sectional CBCT Study

The characteristics of the temporomandibular joint (TMJ) are essential in orthodontic and prosthetic treatments. Previous studies have suggested an association between articular eminence inclinations (AEI) and occlusal plane characteristics using radiographs, but no bilateral analysis has been conducted using cone beam computed tomography (CBCT). Objective: This study aimed to investigate the specific characteristics of the occlusal plane inclinations associated with unilateral and bilateral AEI using CBCT. Methods: We conducted a cross-sectional study to evaluate 200 temporomandibular joints (TMJs) from 100 records obtained at the orthodontic department. We evaluated the association between the AEI, and occlusal plane characteristics like the cant of the occlusal angle, occlusal plane angles, inclination of the upper incisor to the Frankfort plane and palatal plane using both bivariate and multivariate analyses both unilaterally and bilaterally. Results: Our findings suggested statistically significant associations (p < 0.050) between AEI (bilateral) and occlusal inclination parameters, including the cant of the occlusal plane (Coef. -0.38; 95%CI -0.70:-0.06; p = 0.017), occlusal plane angle (Coef. -0.39; 95%CI -0.740:-0.05; p = 0.024), and position of the upper incisor relative to the palatal plane (Coef. -0.34; 95%CI -0.63:-0.06; p = 0.016). Conclusion: This study suggests an association between dental inclinations and AEI, which reflects the anatomical characteristics of TMJ and its related dental structures.

Modifications of the articular eminence inclination in association with the loss of occlusal support in the molar area. A cone-beam computed tomography study

The articular eminence (AE) is part of the temporal component of the temporomandibular joint (TMJ). The inclination of the AE (AEI) has an important role in TMJ biodynamics, influencing the path of movement of the disc-condyle complex. Although AEI values might change due to tooth loss, little is known about what effect could have the loss of occlusal support in the molar area on AE morphology. AEI was measured on cone-beam computed tomography (CBCT) images of 41 patients (82 TMJs) with or without occlusal support in the molar region. The patients included in this study were divided into four groups: (1) patients with maintained occlusal support in the molar areas on both sides (right and left side) (MM); (2) patients with loss of occlusal support in the molar areas on both sides (right and left side) (LL); (3) patients with loss of occlusal support in the molar area only on the right side, but with maintained occlusal support on the left molar area (LM); (4) patients with loss of occlusal support in the molar area only on the left side, but with maintained occlusal support in the right molar area (ML). AEI values were higher in the TMJs on the side with maintained occlusal support in the molar area (M) than the AEI values measured in TMJs from the side with loss of occlusal support in the molar area (L). AEI values on the right side were higher in the MM patients in comparison to the AEI values on the right side of LL patients. The loss of occlusal support in the molar areas changes the mandibular biodynamics, which might be reflected in the morphological changes at the AE level, where it might cause flattening of the articular slope predominantly on the right side.

Assessing the Articular Eminence Asymmetry in Dentate, Partially Edentulous and Edentulous patients Using Cone-Beam Ct

Background and Objectives:

The relationship between the articular eminence (AE) inclination and masticatory system in the biomechanics of temporomandibular joint (TMJ) is defined by the degree with normal values of 30°–60° obtained between the posterior wall of the AE and a horizontal reference plane. The purpose of this study was to assess the asymmetry of the AE in dentate, partially edentulous, and edentulous patients using cone-beam computed tomography (CBCT) imaging and to compare the determined asymmetry in the dentulous with partially and completely edentulous patients.

Materials and Methods:

CBCT images of 120 TMJ joints in sixty patients were evaluated. AE inclination and height values were traced on the central sagittal slice of right and left TMJ. The patients were grouped as dentate, partially edentulous, and edentulous with an age range of 20–80 years. Statistical analysis included student's paired and independent t-test, analysis of variance, and Tukey's post hoc test, and P < 0.05 was considered statistically significant.

Results:

AE inclination revealed highest value in dentate patients (60.98 ± 5.42) followed by partially edentulous (53.40 ± 7.91) and lowest in the edentulous patients (51.43 ± 3.63). P < 0.001 was statistically significant between these groups.

Conclusion:

The results obtained in the present study showed steep inclination of AE in dentate followed by partially edentulous and edentulous subjects. No significant differences among the age, gender, and sides were found.

Factors influencing the articular eminence of the temporomandibular joint (Review)

The temporomandibular joint (TMJ), the most complex and evolved joint in humans, presents two articular surfaces: the condyle of the mandible and the articular eminence (AE) of the temporal bone. AE is the anterior root of the zygomatic process of the temporal bone and has an anterior and a posterior slope, the latter being also known as the articular surface. AE is utterly important in the biomechanics of the TMJ, as the mandibular condyle slides along the posterior slope of the AE while the mandible moves. The aim of this review was to assess significant factors influencing the inclination of the AE, especially modifications caused by aging, biological sex or edentulism. Studies have reported variations in the angles of the slopes of the AE between medieval and recent human dry skulls, as well as between subjects of different racial origin. Recent articles have emphasized the significant role that tooth loss has on the flattening of the AE. Although some papers have described biological sex or age as factors which could be associated with differences in AE angulations, edentulism seems to be a significant factor impacting on the inclination of the AE.

Effects of unilateral posterior missing-teeth on the temporomandibular joint and the alignment of cervical atlas

Cervical atlas alignment changes are associated with craniofacial development. Disturbance of craniofacial development may be associated with temporal mandibular joint function. Therefore, we examined the possibility of a correlation between unilateral missing teeth and morphologic changes of the spine and posture. We collected eighty-nine patients (38 men and 51 women) with unilateral posterior missing teeth and twenty patients without previous orthodontic treatment or missing posterior teeth by tracing and analyzing their panoramic and cephalometric film. We measured the angulations of articular eminence, cranio-cervical angle, and the percentage of the occlusal plane passing through the first and second cervical vertebrae with other morphologic geometric data. The angle of articular eminence inclination was higher in the non-missing teeth group than the missing teeth group (46.66° and 42.28°, respectively). The cranio-cervical angle was smaller in the missing posterior teeth group than the non-missing posterior teeth group (99.81° and 103.27°, respectively). The missing teeth group also showed fewer occlusal planes passing through the intersection of the first and second cervical vertebrae compared to the non-missing teeth group (28.9% and 65%, respectively). Individuals with unilateral missing teeth had lower articular eminence inclination, smaller cranio-cervical angle, and a lower percentage of the occlusal plane passing through the intersection of the first and second cervical vertebrae.

A radiological evaluation of the effects of edentulousness on the temporomandibular joint

BACKGROUND

The articular eminence of the temporomandibular joint is an anatomical structure exposed to functional loads resulting from masticatory forces. Tooth loss may change the biomechanics of the masticator system, and the articular eminence can be affected by this change.

OBJECTIVE

The aim of this study is to examine the relationship between the edentulousness and the articular eminence inclination of the temporomandibular joint.

METHODS

The articular eminence inclination was measured in panoramic radiographs in the right and left temporomandibular joint on a total of 100 patients (50 dentate and 50 edentulous). The articular eminence inclination of dentate and edentulous patients was compared, as well as the influence of gender and duration of edentulousness.

RESULTS

The mean articular eminence inclination value in the dentate group (42.6 ± 4.3⁰ ) was higher than that of the edentulous group (35.1 ± 4.7⁰ , P < .001). Although there was no significant difference between males and females in the dentate group with regard to articular eminence inclination (42.0 ± 4.7⁰ and 42.9 ± 4.1⁰ , respectively, P = .373), in the edentulous group, males had higher values as compared to females (37.1 ± 4.7⁰ and 34.2 ± 4.5⁰ , respectively, P = .003). Finally, the duration of edentulousness and the degrees of articular eminence inclination values did not show positive correlations (P = .782).

CONCLUSION

According to the results of this study, we found that edentulous patients had lower articular eminence inclination than dentate patients, and it was more prominent in female than male patients.

Flattening of the articular eminence is associated with the loss of occlusal support: radiological study

BACKGROUND

Degenerative changes in the temporomandibular joint might be associated with ageing and/or with the loss of occlusal support.

OBJECTIVE

The aim of the study was to evaluate whether the inclination of the posterior slope of the articular eminence changes in association with: (i) ageing in patients with maintained occlusal support zones (OSZs); and (ii) the loss of OSZs in elders.

METHODS

In this retrospective radiological study, selected orthopantomograms were allocated into the following groups: I-age 18-35, maintained OSZs, II-age 36-60, maintained OSZs, III-age >60, at least one OSZ per side maintained, IV-age >60, loss of all OSZs. The inclination of the articular eminence was measured relative to the Frankfort plane.

RESULTS

The mean values of the inclination of the slope of the articular eminence amounted 34.05° ± 5.17°, 36.68° ± 5.65°, 34.86° ± 6.26° and 26.31° ± 5.12° for group I, II, III and IV respectively. There were no significant differences between the groups I to III. Group IV differed significantly from each of the previous groups.

CONCLUSIONS

Flattening of the articular eminence is associated with the loss of OSZs rather than ageing.

Current status and applications of additive manufacturing in dentistry: A literature-based review

Objective

To study the current status and applications of additive manufacturing (AM) in dentistry along with various technologies, benefits and future scope.

Methods

A significant number of relevant research papers on the additive manufacturing application in dentistry are identified through Scopus and studied using bibliometric analysis that shows an increasing trend of research in this field. This paper briefly describes various types of AM technologies with their accuracy, pros and cons along with different dental materials. Paper also discusses various benefits of AM in dentistry and steps used to create 3D printed dental model using this technology. Further, ten major AM applications in dentistry are identified along with primary references and objectives.

Results

Additive manufacturing is an innovative technique moving towards the customised production of dental implants and other dental tools using computer-aided design (CAD) data. This technology is used to manufacture elaborate dental crowns, bridges, orthodontic braces and can also various other models, devices and instruments with lesser time and cost. With the help of this disruptive innovation, dental implants are fabricated accurately as per patient data captured by the dental 3D scanner. The application of this technology is also being explored for the precise manufacturing of removal prosthetics, aligners, surgical templates for implants and produce models that for the planning of treatment and preoperative positioning of the jaws.