Evaluation of the relationship between sleep bruxism and sleeping habits in school-aged children.

OBJECTIVE: To evaluate the relationship between sleep habits and sleep bruxism (SB) in schoolaged children. METHODS: Survey data were collected from the parents of 500 children (267 males and 233 females; age range 6-12 years). The American Academy of Sleep Medicine diagnostic criteria were used to evaluate SB. A Children's Sleep Habits Questionnaire was conducted to determine sleep habits. The chi-square test was used for statistical evaluation. RESULTS: SB was observed in 160 children (32%). SB awareness was 5.4%. The presence of SB in other family members, mothers' education ≤8 years, and income below minimum wage were found as family risk factors. The presence of sleep disorders was 61.4% and observed to be statistically higher in those with SB. CONCLUSION: SB is a prevalent disorder that might be associated with sleep disorders. The parents of children with SB had inadequate knowledge and awareness pertaining to SB.

Evaluation of marginal discrepancy in metal frameworks fabricated by sintering-based computer-aided manufacturing methods.

PURPOSE: The aim of this in vitro study was to evaluate the effect of sintering procedures on marginal discrepancies of fixed partial metal frameworks fabricated using different sintering-based computer-aided design and computer/aided manufacturing (CAD/CAM) techniques. MATERIALS AND METHODS: Forty resin die models of prepared premolar and molar abutment teeth were fabricated using a three-dimensional (3D) printer and divided into four groups (n = 10) according to the fabrication method of metal frameworks used: HM (via hard milling), SM (via soft metal milling), L25 (via direct metal laser melting [DMLM] with a 25 µm layer thickness), and L50 (via direct DMLM with a 50 µm layer thickness). After the metal frameworks were fabricated and cemented, five vertical marginal discrepancy measurements were recorded in each site (i.e., buccal, facing the pontic, lingual, and facing away from the pontic) of both abutment teeth under a stereomicroscope (×40). Data were statistically analyzed at a significance level of 0.05. RESULTS: No statistically significant differences (P>.05) were found among the four axial sites of metal frameworks fabricated by sintering-based CAD/CAM techniques. The HM and L25 groups showed significantly (P<.001) lower marginal discrepancy values than the SM and L50 groups. CONCLUSION: Marginal discrepancy in the sites facing the pontic was not influenced by the type of sintering procedure. All fabrication methods exhibited clinically acceptable results in terms of marginal discrepancies.

Fatigue survival and failure resistance of titanium versus zirconia implant abutments with various connection designs.

STATEMENT OF PROBLEM: Data regarding the effect of connection design and abutment material on the fatigue survival and failure resistance of implant abutments are scarce. PURPOSE: The purpose of this in vitro study was to investigate the effect of connection design and abutment material on the fatigue survival and failure resistance of implant abutment assemblies. MATERIAL AND METHODS: Three types of implants (n=18, N=54) and 6 groups of abutments (n=9, N=54) with different connection designs-internal conical (IC), internal tri-channel (IT), and external hexagonal (EH)-and abutment materials-titanium (T) and zirconia (Z)-were investigated. All the abutments were restored with identical central incisor crowns. Fatigue testing, including thermal and mechanical aging, was performed in a mastication simulator (Esetron Smart Robotechnologies) for up to 1.2×106 cycles with a load of 50 N at an angle of 45 degrees. Then, the surviving specimens were subjected to failure resistance testing in a universal testing machine (Shimadzu AG-IS; Shimadzu Corp) at a crosshead speed of 1.0 mm/min. The maximum loads to failure (N) were recorded. Survival performance of the specimens throughout the fatigue testing was examined by the Kaplan-Meier survival analysis. The failure loads were analyzed by using the Kruskal-Wallis test followed by the Mann-Whitney U tests with Bonferroni-Holm correction (α=.05). RESULTS: All the specimens of groups ICT, ITT, ITZ, and EHT survived fatigue testing, whereas 2 specimens from group ICZ and 3 specimens from EHZ failed. Statistically significant differences were found among the groups, based on the results of maximum failure loads (P<.05). The highest mean failure load was obtained in the ICT group (1069 ±182 N), followed by the ITT (926 ±197 N), EHT (873 ±126 N), ITZ (568 ±81 N), EHZ (311 ±45 N), and ICZ (287 ±63 N) groups. CONCLUSIONS: Abutment material and connection design affected the fatigue survival of implant abutment assemblies. Implant abutment assemblies with a titanium-titanium interface revealed higher failure resistance than the implant abutment assemblies with a titanium-zirconia interface.

Mechanical and optical properties of monolithic CAD-CAM restorative materials.

STATEMENT OF PROBLEM: Achieving natural tooth appearance with sufficient mechanical strength is one of the most challenging issues of computer-assisted design and computer-assisted manufacturing (CAD-CAM) materials. However, limited evidence is available regarding their optical and mechanical properties for proper and evidence-based material selection in clinical practice. PURPOSE: The purpose of this in vitro study was to assess and compare the translucency and biaxial flexural strength of 5 monolithic CAD-CAM restorative materials. MATERIAL AND METHODS: Disk-shaped specimens (n=30) of each material (Lava Ultimate [LU], Vita Enamic [VE], Vitablocs Mark II [VMII], Vita Suprinity [VS], and IPS e.max CAD [IPS]) with a diameter of 12 mm and a thickness of 1.2 ±0.05 mm were prepared. A spectrophotometer was used to measure the translucency parameter. The specimens were then subjected to a biaxial flexure test using 3 balls and loaded with a piston in a universal testing machine at a cross-head speed of 0.5 mm/min until failure occurred (International Organization for Standardization standard 6872). Weibull statistics were used to evaluate the characteristic strength and reliability of each material. Chemical compositions were analyzed using an energy dispersive spectrometer, and microstructural analysis was conducted using scanning electron microscopy. Data were analyzed using 1-way ANOVA and the Tukey honest significant difference test (α=.05). RESULTS: Significant differences were found among the materials concerning translucency and biaxial flexural strength (P<.05). The highest mean transparency value was obtained in the VS group, whereas the lowest mean value was obtained in the VE group. The VS group produced the highest mean biaxial flexural strength, followed by the IPS, LU, VE, and VMII groups. CONCLUSIONS: Based on the results of the present study, zirconia-reinforced glass-ceramic revealed higher mean translucency and biaxial flexural strength than resin nanoceramic, feldspathic ceramic, lithium disilicate ceramic, and dual-network ceramic.