Now is the time to observe and treat dental occlusion

An evaluation of the stress effect of different occlusion concepts on hybrid abutment and implant supported monolithic zirconia fixed prosthesis: A finite element analysis

PURPOSE

The aim of this study is to evaluate the effects of canine guidance occlusion and group function occlusion on the degree of stress to the bone, implants, abutments, and crowns using finite element analysis (FEA).

MATERIALS AND METHODS

This study included the implant-prosthesis system of a three-unit bridge made of monolithic zirconia and hybrid abutments. Three-dimensional (3D) models of a bone-level implant system and a titanium base abutment were created using the original implant components. Two titanium implants, measuring 4 × 11 mm each, were selected. The loads were applied in two oblique directions of 15° and 30° under two occlusal movement conditions. In the canine guidance condition, loads (100 N) were applied to the canine crown only. In the group function condition, loads were applied to all three teeth. In this loading, a force of 100 N was applied to the canine, and 200-N forces were applied to each premolar. The stress distribution among all the components of the implant-bridge system was assessed using ANSYS SpaceClaim 2020 R2 software and finite element analysis.

RESULTS

Maximum stress was found in the group function occlusion. The maximum stress increased with an increase in the angle of occlusal force.

CONCLUSION

The canine guidance occlusion with monolithic zirconia crown materials is promising for implant-supported prostheses in the canine and premolar areas.

Efficacy of Selective Grinding Guided by an Occlusal Splint in Management of Myofascial Pain: A Prospective Clinical Trial

BACKGROUND

For patients whose centric relation (CR) has not been considered at the start and during treatment, the task of achieving an occlusal scheme that works together with the temporomandibular joint, the muscles, and the structures of the stomatognathic apparatus becomes a major concern.

OBJECTIVE

This study aims to describe a reproducible, predictable and to date unreported procedure of selective grinding guided by an occlusal splint and to analyze condylar position (CP) based on the skeletal pattern.

METHODS

A total of 72 symptomatic patients (38 females and 34 males) were classified into three groups: hyperdivergent, intermediate and hypodivergent. CP was quantified by mounted casts on a measures condyle displacement (MCD) device. Helkimo index was also performed in order to assess the severity of the temporomandibular joint (TMJ) disorders attending to clinical dysfunction, occlusal state and anamnestic dysfunction. Once the stability had been obtained, the splint was progressively reduced until the maximum intercuspation (MIC) was achieved.

RESULTS

The vertical displacement was found to be significantly different between the hyperdivergent and other two groups (p<0.01). Comparisons of MCD analysis before and after the selective grinding procedure identified a statistically significant difference in the horizontal and vertical CP (p<0.01) between the different groups whereas the Helkimo Index showed a clear improvement of TMJ disorders.

CONCLUSION

All facial types, specially the hyperdivergent face type, showed a reduction in condylar displacement (CD) and less craniomandibular symptoms using this procedure, making it an excellent technique for clinicians.

Assessment of the Effect of Two Occlusal Concepts for Implant-Supported Fixed Prostheses by Finite Element Analysis in Patients With Bruxism

The aim of this study was to evaluate the effects of bruxing forces on implants configured under 2 different occlusal schemes by dynamic finite element analysis. A main model consisting of a 5-unit fixed partial denture supported by 3 implants was simulated with bone, implants, and superstructures. All calculations were made individually for each component, namely porcelain crowns, abutments, abutment screws, implants, and bone. Maximum stresses were found in the group-function occlusion. Group-function loading may result excess stresses on the components compared with canine-guidance loading. According to the results of this study, use of canine guidance is encouraged in bruxers with implant-supported prostheses.

Quality of life and general health in patients with temporomandibular disorders

The aim of this study was to associate minor psychiatric disorders (general health) and quality of life with temporomandibular disorders (TMD) in patients diagnosed with different TMD classifications and subclassifications with varying levels of severity. Among 150 patients reporting TMD symptoms, 43 were included in the present study. Fonseca's anamnestic index was used for initial screening while axis I of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC-TMD) was used for TMD diagnosis (muscle-related, joint-related or muscle and joint-related). Minor psychiatric disorders were evaluated through the General Health Questionnaire (GHQ) and quality of life was assessed using the World Health Organization Quality Of Life-Brief Version (WHOQOL-BREF). An association was found between minor psychiatric disorders and TMD severity, except for stress. A stronger association was found with mild TMD. Considering TMD classifications and severity together, only the item "death wish" from the GHQ was related to severe muscle-related TMD (p = 0.049). For quality of life, an association was found between disc displacement with reduction and social domain (p = 0.01). Physical domains were associated with TMD classifications and severity and the association was stronger for muscle and joint-related TMD (p = 0.37) and mild TMD (p = 0.042). It was concluded that patients with TMD require multiple focuses of attention since psychological indicators of general health and quality of life are likely associated with dysfunction.

In vitro reproduction of noncarious cervical lesions

STATEMENT OF PROBLEM

A review of the dental literature indicates that noncarious cervical lesions (NCCLs) are formed by erosion, abrasion, and/or abfraction of tooth structure, but their etiology remains scientifically unsubstantiated.

PURPOSE

The purpose of this study was to reproduce noncarious cervical lesions in vitro. This study was not designed to statistically quantify the amount of lost tooth structure via abrasion, but rather to attempt to create NCCLs in the various shapes and sizes that are clinically observed.

MATERIAL AND METHODS

Three pairs of toothbrush types (generic and name-brand) with soft, medium, or firm bristles were tested with 3 different toothpastes of varying abrasive potentials (low, medium, and high) or with water only, on mounted human teeth with and without simulated gingival tissues (6 toothbrushes x 4 brushing solutions (L, M, H, dentifrices, or water only) x 2 gingival mask conditions = 48 test/control groups of 4 teeth each = 192).

RESULTS

The control sets, brushed in water only, demonstrated no visible loss of tooth structure. Each set brushed with toothpaste, regardless of the degree of abrasiveness or toothbrush bristle firmness, demonstrated visible wear at the level of the CEJ.

CONCLUSIONS

Significant noncarious cervical lesions were created via horizontal brushing with common commercial toothpaste, while brushing with water only did not create these cervical lesions.