Background and purpose: The aim of this study was to investigate the relationship between the implant survival rates and the length and diameter in disabled veterans attending Qazi Tabatabai Dental Clinic, Tehran, Iran during 2000-2010.

Materials and methods: A retrospective study was conducted in 181 disabled veterans referring to Qazi Tabatabai Clinic. They received 1,255 implants from three different manufacturers including 3i (Riverside drive, Palm Beach, Gardens, F1, USA), Xive (Friadent GmbH, Mannheim, Germany), and BH (Goteborg, Sweden). The length of implants was classified as short (8-10 mm), medium (11-13 mm), and long (14-15 mm), and the diameter was classified as narrow, regular, and wide. The data analysis was performed using the R statistical software. To evaluate the impacts of the implant length and diameter on its survival rate, the frailty parametric model, with exponential distribution as baseline hazard and gamma distribution as frailty was used.

Results: The mean age and injury rate of the patients were 49.47±5.61 years and 42.98%, respectively. In addition, the estimated medians of survival time for 3i, Xive, and BH implants were 76.15, 79.06, and 77.94 months, respectively. There was no significant difference between the survival rate and type of implant (P=0.353). Regarding the implant length, the 3i implant with with long length (14-15 mm) and the Xive implant with medium length (11-13 mm) had the lowest (88%) and highest success rates (97.8%), respectively. According to the frailty model, the higher length and diameter in 3i and Xive implants were associated with higher failure rates; but this condition was not observed in BH implants.

Conclusion: We found a significant relationship between implant failure and short length implants. However, no relationship was observed between failure of implant and its diameter.

Background and purpose: Bipolar disorder is a mood disorder and mental illness that is recognized as type I and type II. Bipolar I disorder involves at least one episode of mania and is a common chronic recurrence disease with various causes responsible for its recurrence. The aim of this study was to determine effective factors on relapsing disease in patients with bipolar I disorder using frailty model.

Materials and methods: The information of 268 patients with bipolar I disorder who were hospitalized in Farshchian Hospital, Hamedan, Iran (2008-2014) were collected using their records. Patients hospitalized due to more than one recurrence were entered the study. The intervals between recurrence times were recorded. FrailtyPack of R software was used to fit model. 

Results: The mean age of patients was 34.10±11.56 years, and 160 patients (72.7%) were male. In total, 696 recurrences occurred in 268 patients. The number of recurrences was between 2 to 7 times. All patients experienced at least 2 recurrence episodes. The results of fragmented frailty model practice showed significant effect of age, race, place of residence, crime, and type of treatment on relapsing time (P<0.05).

Conclusion: Many factors, including demographics and illness characteristics might cause the recurrence of bipolar disorder, therefore identifying these factors can help in preventing or reducing the incidence of recurrence of this disease.