IntroductionTemporomandibular joint disorder (TMD) is a general term for clinical problems in temporomandibular joints (TMJs), masticatory muscles, and surrounding tissues, which manifest as limitations in motion and joint sounds. 1 TMD is the second most-common skeletal-muscular problem and one of the most common chronic problems involving orofacial pain, discomfort and disability. Approximately 75% of the population has several symptoms of TMD and 33% have at least one symptom. 2-5The etiology of TMD, especially muscle pain, is multifactorial and includes parafunctional habits, trauma, stress, heredity and occlusal factors 5 ; thus, conservative and reversible treatment, especially during initial periods, is recommended. 5,6 Several treatments have been suggested to control pain and symptoms. These include orthopedic stabilization, intraoral devices, medications (analgesics, muscle relaxants, antidepressants, and placebos) and physical therapy. 5 The aim of physical therapy is muscle relaxation, a decrease in pain, spasms, swelling and inflammation, and joint stability. Methods:In this single-blind study, 40 patients with temporomandibular disorders were randomly divided into four groups: TENS (TENSTem dental), LLL (diode 810 nm CW), sham-TENS, and sham-LLL. All subjects were examined and data on pain and tenderness in the temporomandibular joint (TMJ) and masticatory muscles (using the visual analogue scale) and mouth-opening (distance between incisal edges before feeling pain; mm) were collected before baseline (T1), after each session (T2-T5) and one month after the end of the sessions (T6)), and analyzed using repeated measure analysis of variance (ANOVA) and Bonferroni statistical tests. A P value < 0.05 was considered significant. Results:The decrease in pain (P = 0.000), tenderness (P = 0.000) and increase in mouth-opening ability (P = 0.002) was greater in the TENS and LLL groups than in the placebo groups. At the one-month follow-up, significant decrease in pain and tenderness was recorded in the TENS and LLL groups (P = 0.000). There was no significant differences between TENS and LLL and the placebo groups for maximum mouth-opening at the end of the study (P = 0.692). Conclusion: Using TENS or LLL therapy can improve TMD symptoms at least for the short term. Although the effects of the placebo played a role in improving symptoms, their effects were less important.
Objective:Growth prediction plays a significant role in accurate diagnosis and treatment planning of orthodontics patients. It was hypothesized that the unique pattern of pneumatization of the frontal sinus as a component of craniofacial structure would influence the skeletal growth pattern and may be used as a growth predictor.Materials and Methods:A total of 144 subjects (78 females and 66 males) with a mean age of 19.26 ± 4.66 years were included in this retrospective study. Posterior-anterior and lateral cephalograms (LCs) were used to measure the frontal sinus dimensions. The skeletal growth pattern and relations of craniofacial structures were analyzed on LC using variables for sagittal and vertical analyses. Correlation between the frontal sinus dimensions and cephalometric indices was assessed by the Pearson's correlation coefficient.Results:The SN-FH and SNA angles had significant associations with frontal sinus dimensions in all enrolled subjects (P < 0.05). In males, the SN-FH, sum of posterior angles, Pal-SN, and Jarabak index were significantly associated with the size of frontal sinus (P < 0.05). In females, the associations of SN-FH and gonial angles with frontal sinus dimensions were significant (P < 0.05).Conclusion:The results show that larger size of frontal sinus was associated with reduced inclination of the anterior cranial base, increased anterior facial height (in males), and increased gonial angle (in females) in the study population.
Objectives:This study sought to assess the effect of bracket base design on the shear bond strength (SBS) of the bracket to feldspathic porcelain.Materials and Methods:This in vitro, experimental study was conducted on 40 porcelain-fused-to-metal restorations and four different bracket base designs were bonded to these specimens. The porcelain surfaces were etched, silanized, and bonded to brackets. Specimens were thermocycler, incubated for 24 h and were subjected to SBS. Data were analyzed using Shapiro–Wilk test, Levene's test, one-way ANOVA, and Tukey's honest significant difference test. Adhesive remnant index was calculated and compared using Fisher's exact test.Results:One-way ANOVA showed that the SBS values were significantly different among the four groups (P < 0.001). Groups 1, 2, and 4 were not significantly different, but group 3 had significantly lower SBS (P < 0.001). Fractures mostly occurred at the porcelain-adhesive interface in Groups 1 and 2 while in Groups 3 and 4, bracket-adhesive and mixed failures were more common.Conclusion:The bracket base design significantly affects the SBS to feldspathic porcelain.
Objectives: The aim of this study was to assess the shear bond strength (SBS) of zirconia ceramic to composite resin with various surface treatments following pressure changes. Materials and Methods: Totally, 135 zirconia blocks were prepared by computer-aided design/computer-aided manufacturing technology. The samples were divided into 9 groups (n=15). Three surface treatments including sandblasting, tribo-chemical preparation, and laser application were used. For each method, 45 samples were considered and tested under different pressure conditions. Z-Prime Plus primer was used for bonding of all samples to composite cylinders. All specimens were stored in water for 24 h, underwent thermocycling, and were then placed in a pressure chamber under normal-, high-, and low-pressure conditions. Then, the SBS test was performed for each sample. Data were analyzed by two-way and one-way ANOVA (α=0.05). Results: The SBS was significantly higher in sandblasting and tribochemical preparation compared with laser irradiation (P<0.05). There was no statistically significant difference in SBS of sandblasting and tribochemical preparation methods (P>0.05). Sandblasting, tribochemical preparation, and laser methods did not show a significant difference in SBS at different pressures (P>0.05). Conclusion: Sandblasting and tribochemical preparation yielded a higher SBS than laser. Different pressures had no effect on SBS, irrespective of surface preparation method.
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