Development and Validation of an Ultrasonography-Based Machine Learning Model for Predicting Outcomes of Bruxism Treatments.

BACKGROUND AND OBJECTIVES: We aimed to develop a predictive model for the outcome of bruxism treatments using ultrasonography (USG)-based machine learning (ML) techniques. This study is a quantitative research study (predictive modeling study) in which different treatment methods applied to bruxism patients are evaluated through artificial intelligence. MATERIALS AND METHODS: The study population comprised 102 participants with bruxism in three treatment groups: Manual therapy, Manual therapy and Kinesio Tape or Botulinum Toxin-A injection. USG imaging was performed on the masseter muscle to calculate muscle thickness, and pain thresholds were evaluated using an algometer. A radiomics platform was utilized to handle imaging and clinical data, as well as to perform a subsequent radiomics statistical analysis. RESULTS: The area under the curve (AUC) values of all machine learning methods ranged from 0.772 to 0.986 for the training data and from 0.394 to 0.848 for the test data. The Support Vector Machine (SVM) led to excellent discrimination between bruxism and normal patients from USG images. Radiomics characteristics in pre-treatment ultrasound scans of patients, showing coarse and nonuniform muscles, were associated with a greater chance of less effective pain reduction outcomes. CONCLUSIONS: This study has introduced a machine learning model using SVM analysis on ultrasound (USG) images for bruxism patients, which can detect masseter muscle changes on USG. Support Vector Machine regression analysis showed the combined ML models can also predict the outcome of the pain reduction.

Effect of different surface treatments on the biaxial flexural strength of zirconia ceramics.

STATEMENT OF PROBLEM: Different surface treatments have been applied to zirconia restorations in clinical practice to increase the bond strength between zirconia and cement, but their effect on flexural strength is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the effect of different surface treatments before and after sintering on the flexural strength of zirconia. MATERIAL AND METHODS: Sixty disk-shaped specimens with an initial diameter of 18.6 ±0.1 mm and thickness of 2 ±0.1 mm were prepared from preshaded presintered 3Y-TZP blocks. The specimens were randomly divided into 3 groups (n=20) according to surface treatments (Group Laser, Group APA, Group Rocatec), and the groups were then divided into 2 subgroups (n=10) according to surface treatment before and after sintering. The phase compositions of the groups were examined by using an X-ray diffractometer (XRD) with 3 randomly selected specimens from each group. Biaxial flexural strength testing was conducted using a universal testing machine to examine the flexural strength of the zirconia specimens. Two-way ANOVA and post hoc least significant difference tests were performed (α=.05). RESULTS: According to the XRD analysis, no monoclinic phases were determined on the surface of the presintered laser-treated specimens, but tetragonal phases were observed on the surface of the postsintered specimens. Surface treatment type and application stage (presintering to postsintering) have a significant effect on the biaxial flexural strength of the specimens (P<.05). The lowest biaxial flexural values were observed in the Laser group, and postsintered specimens showed higher biaxial flexural strength than presintered specimens (P<.05). CONCLUSIONS: Postsintered specimens showed higher monoclinic content than presintered specimens. Laser-treated specimens showed the lowest biaxial flexural strength for both presintered and postsintered specimens.

Evaluation of the fracture resistance of root filled thin walled teeth restored with different post systems.

BACKGROUND: Restoration of the teeth with extensive root canals with different post systems is a challenge for clinicians. Evaluation of these systems is important for clinical success. The aim of this study was to compare the fracture resistance and fracture mode of endodontically treated thin-walled teeth which restored with different post systems. METHODS: Eighty extracted and endodontically treated maxillary canines were divided into 4 groups (n = 20) and the thickness of the radicular dentin walls was reduced by using diamond burs. Each root was embedded in an autopolymerizing resin with a 0.25 mm layer of vinyl polysiloxane material to simulate the periodontal ligament. The subgroups were restored with one of the following post systems: only composite resin (Group 1), cast post (Group 2), glass-fiber post (Group 3), and I-TFC post (Group 4). The samples were subjected to a gradually increasing force (0,5 mm/min). The force required to fracture was recorded, and the data were analyzed with ANOVA, Tukey test's and Chi-Square test (p < 0.05). RESULTS: The highest fracture resistance was recorded for Group 2, followed by the Group 3, Group 4, and Group 1. Differences in the fracture resistance of teeth were significant among the groups (p < 0.05). The fracture resistance of Group 4 was significantly different than the other tested post systems (p < 0.05). CONCLUSIONS: The lowest fracture resistance was recorded for Group 1, but among all post systems, Group 4 had the lowest fracture resistance. The fracture mode of the fiber posts (Radix and I-TFC posts) would permit repair of the tooth.

Influence of different surface finishing techniques on machinable feldspathic and leucite-reinforced ceramics.

The effect of surface finishing techniques on machinable ceramics to obtain optimum smoothness is unclear. The aim of the study was to evaluate the effects of surface finishing techniques on machinable feldspathic and leucite-reinforced ceramics. Forty specimens were divided into four subgroups according to surface finishing techniques and ceramic structure. A profilometer was used to evaluate surface roughness. A spectrophotometer was used to obtain the CIE L*, a* and b* coordinates. All specimens were subjected to a three-point bending test to determine flexural strength. All data were analyzed with two-way ANOVA and Tukey's HSD tests (p<0.05). Polishing techniques were found to be more effective than the glazing method to obtain smooth surfaces. Glazing technique increased the flexural strength of leucite-reinforced ceramics. Finishing procedures have different effects on the success of the restorations and must be considered by the clinicians.

Evaluation of the retention characteristics of various stud attachment systems for implant retained overdenture.

PURPOSE: The purpose of the study was to analyze and compare retention characteristics of different stud attachments including a standard and two low profile attachments on two implant embedded test models. METHODS: Three different stud attachment systems (Ball attachment and two different low profile stud attachments - Equator and Locator) were used in this study. Two dental implants were placed vertically into a custom-made acrylic resin block within a 22 mm distance. Strong and soft nylon inserts of each attachment system were tested using cyclic dislodgement test for 24 months simulation. Maximum forces during the test were recorded and 10 consecutive data at baseline, 1st to 24th months were analyzed. Repeated measures ANOVA and post-hoc Tukey's test (p ≤0.05) were used for statistical analysis. RESULTS: Retentive forces of the tested attachments varied from 30.7 to 93.75 N at the baseline. The highest initial mean retention (93.75 N) was observed in Group LC (locator attachment with clear nylon inserts) and the lowest initial mean retention (30.7 N) was detected in both Group BO (ball attachment with orange nylon inserts) and Group EY (equator with yellow nylon inserts). After the 24 months simulation, locator groups illustrated more light retention than other tested attachment systems. CONCLUSIONS: All tested attachment systems showed a significant decrease in retention value at the end of the simulated period. The locator attachment had significantly higher reduction in retention values compared to other low profile stud attachment equator and ball attachment.

A technique for retrofitting a metal ceramic crown to an attachment-retained removable partial denture: a clinical report.

In dental applications, precision attachments have been used to retain removable partial dentures (RPDs) for several decades. Various types of extracoronal attachments are commonly used in combination with fixed partial dentures and RPDs to achieve retention and stability. Fracture of the framework, fracture of the roots or teeth, and irretrievable decrease of retention are common reasons for a failed attachment-retained RPD. Another complication of metal ceramic crowns with precision attachment is decementation of the crowns. When fixed components of the attachment-retained RPD fail, the traditional treatment approach requires remaking both the fixed and removable components of the attachment-retained RPD. This technique describes retrofitting of a metal ceramic crown to a resilient attachment-retained RPD.

The effect of repeated firings on the color change and surface roughness of dental ceramics.

PURPOSE: The color of the ceramic restorations is affected by various factors such as brand, thickness of the layered the ceramic, condensation techniques, smoothness of surface, number of firings, firing temperature and thickness of dentin. The aim of this study was to evaluate the color change and surface roughness in dental porcelain with different thicknesses during repeated firings. MATERIALS AND METHODS: Disc-shaped (N=21) metal-ceramic samples (IPS Classic; Ivoclar Vivadent; Shaar, Liechtenstein) with different thickness were exposed to repeated firings. Color measurement of the samples was made using a colorimeter and profilometer was used to determine surface roughness. ANOVA and Tukey tests with repeated measurements were used for statistical analysis. RESULTS: The total thickness of the ceramics which is less than 2 mm significantly have detrimental effect on the surface properties and color of porcelains during firings (P<.05). CONCLUSION: Repeated firings have effects on the color change and surface roughness of the dental ceramics and should be avoided.

The effect of repeated firings on the color change of dental ceramics using different glazing methods.

PURPOSE: Surface color is one of the main criteria to obtain an ideal esthetic. Many factors such as the type of the material, surface specifications, number of firings, firing temperature and thickness of the porcelain are all important to provide an unchanged surface color in dental ceramics. The aim of this study was to evaluate the color changes in dental ceramics according to the material type and glazing methods, during the multiple firings. MATERIALS AND METHODS: Three different types of dental ceramics (IPS Classical metal ceramic, Empress Esthetic and Empress 2 ceramics) were used in the study. Porcelains were evaluated under five main groups according to glaze and natural glaze methods. Color changes (ΔE) and changes in color parameters (ΔL, Δa, Δb) were determined using colorimeter during the control, the first, third, fifth, and seventh firings. The statistical analysis of the results was performed using ANOVA and Tukey test. RESULTS: The color changes which occurred upon material-method-firing interaction were statistically significant (P<.05). ΔE, ΔL, Δa and Δb values also demonstrated a negative trend. The MC-G group was less affected in terms of color changes compared to other groups. In all-ceramic specimens, the surface color was significantly affected by multiple firings. CONCLUSION: Firing detrimentally affected the structure of the porcelain surface and hence caused fading of the color and prominence of yellow and red characters. Compressible all-ceramics were remarkably affected by repeated firings due to their crystalline structure.