[Precise investigation of digital guide plates applied to implant surgery of anterior teeth].

OBJECTIVE: To study the precision of digital guide plates applied to the implant surgery of anterior teeth. METHODS: Fifty patients scheduled to receive implant restoration treatment in anterior teeth were enrolled in this study and divided into two groups (n=25, each group): those who were given routine implant restoration treatment (control group, 45 implants) and those who received implant restoration treatment using a digital guide plate (test group, 51 implants). After implantation, planned and placed implants were superimposed using digital software, and deviations (corona, apex, depth, degree) were analyzed. Esthetic parameters were assessed at 1 week (baseline), 6 month, and 1 year post final restoration. Pink esthetic (PES) and white esthetic (WES) scores were respectively used to evaluate the soft tissue and restoration esthetic outcome. RESULTS: The deviation parameters in the test group were significantly lower than those in the control group (P<0.05). PES and WES values recorded for the control group at 1 week, 6 month, and 1 year post final restoration were significantly lower than those in the test group (P<0.05). CONCLUSIONS: The digital guide plate can improve the accuracy of the three-dimensional position of implants in the maxillary esthetic zone. As such, this device may play an important role in obtaining the ideal aesthetic effects of maxillary anterior teeth.

Inducible expression of cre recombinase in the retinal pigmented epithelium.

PURPOSE: The retinal pigmented epithelium (RPE) expresses many genes that play important roles in the support and maintenance of photoreceptors. The present study was conducted to develop a system amenable to the dissection of the temporal function of these genes, specifically within RPE cells. Transgenic mice were generated and characterized in which the expression of Cre recombinase could be specifically induced within the RPE. METHODS: Transgenic mice carrying the human vitelliform macular dystrophy-2 (VMD2) promoter (P(VMD2))-directed reverse tetracycline-dependent transactivator (rtTA) and the tetracycline-responsive element (TRE)-directed cre were generated. Inducible Cre expression was achieved by feeding doxycycline to these mice and was characterized by using a Cre-activatable lacZ reporter mouse strain (R26R). RESULTS: A beta-galactosidase assay of rtTA/Cre-R26R mice demonstrated that the basal level of Cre expression without doxycycline induction was negligible. Addition of doxycycline led to induction of RPE-specific Cre expression/function at least from embryonic day 9 to postnatal day 60. The highest induction occurred at approximately postnatal day 4. As measured by ERG and histology, retinal function and morphology were normal in 10-month-old rtTA/Cre mice that were treated with doxycycline at weaning age. CONCLUSIONS: Transgenic mice were generated that express Cre recombinase in the RPE in an inducible fashion. These mice will be useful for studies of the RPE-specific role of genes that are expressed in the RPE as well as other cells, particularly for avoiding embryonic lethality and dissecting the function of genes that play dual roles in development and adulthood.