Journal of Dental Medicine

Background and Aims: To create a good adhesion between porcelain veneers and zirconia restorations has been important issues is the prosthesis. The aim of this study was to identify an effective way to prepare the zirconia surface infrastructure to increase its shear bond strength to the porcelain veneer.
Materials and Methods: 75 samples of zirconia (Y-TZP) cylinders (diameter of 7 mm and a thickness of 3 mm) were fabricated. Based on the surface treatment, specimens were randomly divided into 3 groups: control, air abrasion and
Er-YAG laser. After surface treatment, the specimen surfaces were examined by SEM. Using a metal mold, the porcelain was veneered on the zirconia surface and then fired. After thermocycling, the shear bond strength of porcelain to zirconia was measured and then the failure mode of each specimen was analyzed using a stereo-microscope. Data were analyzed by one-way ANOVA and Tukey test.
Results: Significant differences were observed between the mean shear bond strength of different groups (P=0.001). The greatest amount of shear bond strength was observed in the group (S) and the lowest bond strength in the control group. Analysis of failure modes showed no statistically significant difference in the type of failure among study groups. The adhesive failure was predominating failure at the intersection of porcelain veneers.
Conclusion: The highest shear bond strength between zirconia and porcelain was achieved by sandblasting the zirconia surfaces compare with that of Er_YAG application.

Background and Aims: Sleep quality may be a predictive factor for temporomandibular disorders (TMD) compared to other risk factors. Patients with TMD may experience quality-of-life problems such as sleep disorders and orofacial pain. Timely diagnosis of TMD can halt its progression in the initial stages and reduce its severity. This study aimed to investigate the frequency and severity of temporomandibular joint disorders and their co-occurrence with sleep quality among dental students in Yazd in 2023.
Materials and Methods: This descriptive study was conducted among 211 students at the Yazd Dental School. The Fonseca and PSQI questionnaires were used to determine the severity of TMD and sleep quality, respectively. Clinical examination was conducted to assess the symptoms of TMD. Additionally, demographic information such as gender, marital status, and place of residence was recorded. The data were analyzed using chi-square and t-tests.
Results: The final analysis was performed on 211 individuals, comprising 118 males (56%) and 93 females (44%). Among all the participants, 204 individuals (83.88%) had at least one symptom of TMD.  The participants' most prevalent symptoms were jaw sounds, midline deviation, pain, and mouth opening limitation. There was no significant difference in the frequency of TMD symptoms, jaw sounds, jaw deviation, and limitation in opening, based on gender. Similarly, the prevalence and severity of TMD and their symptoms showed no significant association with residence or marital status (P>0.05). Although, a correlation was observed between the poor sleep quality and the severity of TMD, no association was found between the presence of TMD symptoms and poor sleep quality (P>0.05).
Conclusion: While, the frequency of TMD symptoms did not differ significantly between genders, the severity of TMD and jaw pain was significantly higher among female students. Individuals with poor sleep quality exhibited significantly higher severe degree of TMD.

Background and Aims: Despite significant advancements in rehabilitation of edentulism with implants, complications such as implant failure before and after prosthetic loading remain concerns. This study aimed to evaluate the frequency of dental implant failure before and after prosthetic loading in some of Yazd dental clinics between 2018 and 2023.
Materials and Methods: In this descriptive cross-sectional study, 1060 patients’ files from three public dental clinics were reviewed. These patients were treated by dental implants between April 2018 and June 2023. The collected data included patients’ age and gender, implant diameter, brand, and placement site, type of prosthesis, and fixture failure after surgical and prosthetic phases. Data were statistically analyzed by independent t-tests and chi-square tests.
Results: The mean age of patients was 55.25 ± 12.37 years and 56.3% were female. The frequency of overall implant failure was 3.4%. The implant failure rate after prosthetic loading was 2.8% in females and 2.3% in males (P=0.47). This rate was 2% and 1.9% for maxillary and mandibular implants, respectively (P=0.5). This amount was 2.4% in molar areas,1.7% and 1.8% in premolar and anterior regions, respectively  (P=0.8). Implant failure rate was 1.3% in overdentures, 5.9% in cement-retained, and 3.2% in screw-retained prosthesis (P<0.001). This amount for implants with a diameter less than 3.75 mm was 2.6% and for those with a diameter more than 4.5 mm was 3.7% (P<0.001). Implants with a diameter less than 3.75 mm had a 2.6% failure rate, whereas those with a diameter greater than 4.5 mm had a 3.7% failure rate (P<0.001). The implants failure rate was 1.6% for Dio brand and 2.5% for Dentis (P=0.5).
Conclusion: The overall implant failure rate in this study was 3.4%, of which 1.5% occurred before and 1.9% occurred after prosthetic loading. The frequency of implant failure after loading was significantly associated with the implant diameter and prosthesis type. This was not related to the patient's gender, implant site, or the implant brand.