The effect of mucosal cuff shrinkage around dental implants during healing abutment replacement.

Soft tissue shrinkage during the course of restoring dental implants may result in biological and prosthodontic difficulties. This study was conducted to measure the continuous shrinkage of the mucosal cuff around dental implants following the removal of the healing abutment up to 60 s. Individuals treated with implant-supported fixed partial dentures were included. Implant data--location, type, length, diameter and healing abutments' dimensions--were recorded. Mucosal cuff shrinkage, following removal of the healing abutments, was measured in bucco-lingual direction at four time points--immediately after 20, 40 and 60 s. anova was used to for statistical analysis. Eighty-seven patients (49 women and 38 men) with a total of 311 implants were evaluated (120 maxilla; 191 mandible; 291 posterior segments; 20 anterior segments). Two-hundred and five (66%) implants displayed thick and 106 (34%) thin gingival biotype. Time was the sole statistically significant parameter affecting mucosal cuff shrinkage around dental implants (P < 0.001). From time 0 to 20, 40 and 60 s, the mean diameter changed from 4.1 to 4.07, 3.4 and 2.81 mm, respectively. The shrinkage was 1%, 17% and 31%, respectively. The gingival biotype had no statistically significant influence on mucosal cuff shrinkage (P = 0.672). Time required replacing a healing abutment with a prosthetic element should be minimised (up to 20/40 s), to avoid pain, discomfort and misfit.

Incorporation of chlorhexidine diacetate in provisional cements: antimicrobial activity against Streptococcus mutans and the effect on tensile strength in vitro.

AIM: To test the antibacterial capacities and tensile strengths of three commercially available provisional cements to which chlorhexidine diacetate was added and compare them to the same unmodified cements. METHODOLOGY: Sixty cylindrical samples were prepared from either three noneugenol provisional cements or the same cements modified by the addition of chlorhexidine diacetate at 7.5% w/w, with a total of 360 samples. The cements tested included Tempbond NE, Rely X Temp NE and Freegenol. Forty-eight samples from each cement were aged in saline that was replaced twice a week for up to 96 days. Twelve of these samples were removed at either 1, 15, 30 or 96 days and assessed for antibacterial properties against Streptococcus mutans with an agar diffusion test. Twelve samples of each cement, with and without chlorhexidine diacetate, were also tested 7 days after the initial setting for their tensile strength using a diametrical tensile strength test applied with an Instron machine. The results were analysed using either one-way or three-way anova. RESULTS: The addition of chlorhexidine diacetate resulted in provisional cements with antibacterial properties that persisted through ageing in saline for up to 96 days. The addition of chlorhexidine did not reduce the diametrical strength of the cements. CONCLUSIONS: The addition of chlorhexidine diacetate to provisional cements rendered all three cements antibacterial against S. mutans and this activity was maintained even after prolonged ageing of the cements, without compromising their tensile strength at 7 days.