AIMTo investigate the relationship between germ cell degeneration and apoptosis in cryptorchid rats.

METHODSThirteen 21-day-old Wistar rats were made unilaterally cryptorchid by closing the left inguinal canal. At day 30 (Group 1, n=6) and day 60 (Group 2, n=7) after operation, the testes were removed for histopathological examination. The controls (n=8) were sham operated and were sacrificed at day 60. Germ cell apoptosis was assessed by means of the TUNEL method.

RESULTSSpermatogenesis was arrested and the testicular and seminiferous tubular diameters were significantly reduced In the unilateral undescended testes (UUTs) compared with the contralateral descended testes (CDTs) and the control rats. However, atrophic changes, pathological calcification, necrosis of seminiferous tubule, and absence or sloughing of germ cells were not found in all the animals. The spermatocytes were the main type of germ cells undergoing apoptosis in all the groups. In the UUTs, there was a significant and time-dependent increase in the mean apoptotic index. By 60 days after surgery, increased apoptosis in germ cells was also observed in the CDTs.

CONCLUSIONApoptosis is the predominant mechanism of germ cell death rather than atrophy and necrosis in cryptorchidism.

Animals ; Apoptosis ; Cryptorchidism ; pathology ; In Situ Nick-End Labeling ; Male ; Rats ; Rats, Wistar ; Spermatocytes ; pathology

PURPOSE: Zirconia materials have been used for implant-retained restorations, but the stress distribution of zirconia is not entirely clear. The aim of this study is to evaluate the stress distribution and risky areas caused by the different design of zirconia restorations on the atrophic bone of the posterior maxilla. MATERIALS AND METHODS: An edentulous D4-type bone model was prepared from radiography of an atrophic posterior maxilla. Monolithic zirconia and zirconia-fused porcelain implant-retained restorations were designed as splinted or non-splinted. 300-N occlusal forces were applied obliquely. Stress analyses were performed using a 3D FEA program. RESULTS: According to stress analysis, the bone between the 1) molar implant and the 2) premolar in the non-splinted monolithic zirconia restoration model was stated as the riskiest area. Similarly, the maximum von Mises stress value was detected on the bone of the non-splinted monolithic zirconia models. CONCLUSION: Splinting of implant-retained restorations can be more critical for monolithic zirconia than zirconia fused to porcelain for the longevity of the bone.
Bicuspid ; Bite Force ; Dental Implants ; Dental Porcelain ; Finite Element Analysis ; Longevity ; Maxilla ; Molar ; Radiography ; Splints