PURPOSEThe aim of the present study was to evaluate the fracture resistances of zirconia, cast nickel-chromium alloy (Ni-Cr), and fiber-composite post systems under all-ceramic crowns in endodontically treated mandibular first premolars.MATERIALS AND METHODSA total of 36 extracted human mandibular premolars were selected, subjected to standard endodontic treatment, and divided into three groups (n=12) as follows: cast Ni-Cr post-and-core, one-piece custom-milled zirconia post-and-core, and prefabricated fiber-glass post with composite resin core. Each specimen had an all-ceramic crown with zirconia coping and was then loaded to failure using a universal testing machine at a cross-head speed of 0.5 mm/min, at an angle of 45 degrees to the long axis of the roots. Fracture resistance and modes of failure were analyzed. The significance of the results was assessed using analysis of variance (ANOVA) and Tukey honest significance difference (HSD) tests (α=.05).RESULTSFiber-glass posts with composite cores showed the highest fracture resistance values (915.70±323 N), and the zirconia post system showed the lowest resistance (435.34±220 N). The corresponding mean value for the Ni-Cr casting post and cores was reported as 780.59±270 N. The differences among the groups were statistically significant (P<.05) for the zirconia group, as tested by ANOVA and Tukey HSD tests.CONCLUSIONThe fracture resistance of zirconia post-and-core systems was found to be significantly lower than those of fiberglass and cast Ni-Cr post systems. Moreover, catastrophic and non-restorable fractures were more prevalent in teeth restored by zirconia posts.

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AimThe first step in the management of Temporomandibular Disorders (TMD) is usually noninvasive, especially if the disorder is in the early stages. Clinically, pain and clicking are early signs and symptoms of TMD. The management of TMD usually includes “splint therapy” and analgesics. In this study, we report our long-term outcomes in the treatment of patients suffering from early TMD.Materials and Methods:We assessed the records of 138 patients who were referred for management of TMD. Selection was based on pain and/or clicking of the Temporomandibular Joint (TMJ), no pathologic lesions of the TMJ, no anterior disc displacement without reduction (closed lock), no Degenerative Joint Disease, no history of migraine, trauma, osteoarthritis, metabolic disease, or malocclusion (deep bite, cross bite, jaw deformity, etc). The patients were treated with an acrylic maxillary Interocclusal Splint (IOS) cuspid-rise type and were told to refrain from biting, yawning and chewing hard food. The outcome of the treatment, potential etiologic factors (Bruxism), signs and symptoms and patient demographics (such as age, sex, treatment duration, etc.) were assessed. The data were analyzed using the Chi-square test to correlate significance.Results:One hundred thirty-eight patients (26 males and 112 females) with early signs and symptoms of TMD (pain and/or click of the TMJ) were treated from 2001 to 2010; 81% were females and 19% were males. All the 138 patients used the IOS at night only. The patients were followed-up for 1–9 years. Data analysis showed that 64% of the patients were completely relieved of signs and symptoms; 22% were moderately relieved (decreased severity of signs and symptoms) and 14% had no noticeable post-treatment changes in clicking or pain (P = 0.001). Patients with bruxism and those presenting with both pain and clicking showed a better response to IOS treatment (P = 0.046 and P = 0.001, respectively). The results also showed that age, sex, severity of symptoms and duration of the treatment did not influence treatment results in this group of patients with early TMD.Conclusion:In this population, TMD was significantly higher in females. Treatment of early TMD with IOS was effective and moderately effective in long-term in over 80% of the patients during the follow-up period of 1–9 years. Bruxism had a significant etiologic role in TMD; occlusal attrition of the dentition, pain of all the teeth, early morning pain of the masticatory muscles and the TMJ are signs and symptoms to suspect nocturnal bruxism. Use of an IOS is recommended to prevent potential damage to the dentition, periodontium and the TMJ in early TMD.

Background and Aim: Marginal adaptation has a significant role in the success and longevity of indirect restorations. This experimental study compared the effect of intraoral and extraoral scanning on the marginal adaptation of the crowns which was made using the CEREC AC system. Materials and Methods: A Typodont maxillary first molar was prepared and served as the master die for an all-ceramic restoration. In the first group, the model was scanned ten times directly by the intraoral scanner. In the second group, ten conventional impressions were made from Typodont, and the extraoral scanner scanned the resulting gypsum casts. The data was used to design and build crowns from IPS e.max CAD blocks. The crowns were placed on the prepared tooth, and the marginal gap was measured at 16 points by a stereomicroscope at ×35 magnification. Collected data were analyzed using t-test. Results: The mean marginal gap for intraoral and extraoral groups were 74.83 ± 10.07 μm and 102.56 ± 6.89 μm respectively. The gap was significantly less in the intraoral group (P-value = 0.001). Conclusion: Marginal adaptation was clinically acceptable in both groups, although the results of intraoral scanning showed significantly lower gap than extraoral scanning.