Role of supportive maintenance therapy on implant survival: a university-based 17 years retrospective analysis.

OBJECTIVE: The objective of this study was to determine whether professional maintenance appointments were related to a decrease on dental implant loss. METHODS: We performed a retrospective review (1995-2012) of 1020 patient dental charts to collect data including a cadre of different variables such as age, gender, race, diabetes, osteoporosis, jaw location, implant dimensions and professional maintenance therapy. As a patient may have multiple implants which are correlated, we selected one random implant per patient to assure independence of observations assumption of the Cox proportional hazards regression model. Data analysis was performed using Kaplan-Meier survival curves and multivariate analysis using Cox proportional hazards regression analysis. RESULTS: Our results demonstrate that subjects with no maintenance had the lowest cumulative survival rate as compared to subjects with regular maintenance. In a multivariate Cox regression model, regular maintenance patients had the dental implant failure rate reduced by 90% as compared to no maintenance (P = 0.001). If patients had less than one maintenance visit per year, the failure rate was reduced by 60% as compared to no maintenance, but the difference was not statistically significant (P = 0.08). CONCLUSION: From this research, we conclude that a professional administered periodontal maintenance at least on an annual basis is a critical factor for implant survival.

Isolation and characterization of multipotent human periodontal ligament stem cells.

BACKGROUND: Periodontal ligament (PDL) repair is thought to involve mesenchymal progenitor cells capable of forming fibroblasts, osteoblasts and cementoblasts. However, full characterization of PDL stem cell (SC) populations has not been achieved. OBJECTIVE: To isolate and characterize PDLSC and assess their capability to differentiate into bone, cartilage and adipose tissue. METHODS: Human PDL cells were stained for STRO-1, FACS sorted and expanded in culture. Human bone marrow SC (BMSC) served as a positive control. PDLSC and BMSC were cultured using standard conditions conducive for osteogenic, chondrogenic and adipogenic differentiation. Osteogenic induction was assayed using alizarine red S staining and expression of alkaline phosphatase (ALP) and bone sialoprotein (BSP). Adipogenic induction was assayed using Oil Red O staining and the expression of PPAR gamma 2 (early) and LPL (late) adipogenic markers. Chondrogenic induction was assayed by collagen type II expression and toluidine blue staining. RESULTS: Human PDL tissue contains about 27% STRO-1 positive cells with 3% strongly positive. In osteogenic cultures ALP was observed by day-7 in BMSC and day-14 in PDLSC. BSP expression was detectable by day-7; with more intense staining in PDLSC cultures. In adipogenic cultures both cell populations showed positive Oil Red O staining by day-25 with PPAR gamma 2 and LPL expression. By day-21, both BMSC and PDLSC chondrogenic induced cultures expressed collagen type II and glycosaminoglycans. CONCLUSIONS: The PDL contains SC that have the potential to differentiate into osteoblasts, chondrocytes and adipocytes, comparable with previously characterized BMSC. This adult PDLSC population can be utilized for potential therapeutic procedures related to PDL regeneration.