Outcomes of Mandibular Overdentures Supported by Four Short Implants Combined with Photobiomodulation Therapy.

PURPOSE: The aim of this study was to clinically and radiographically evaluate mandibular overdentures supported by four short implants combined with two different doses of photobiomodulation (PBM). MATERIALS AND METHODS: A split-mouth design was applied; six completely edentulous male subjects received four short implants in the canine and second premolar area. Short implants were inserted via a digital fully guided approach with a stereolithographic surgical guide. All patients received five PBM sessions immediately after surgery and every 48 hours. Group A (n = 6) implants on the right side received a dose of 3.75 J/cm2, and group B (n = 6) implants on the left side received a dose of 7.5 J/cm2. Evaluation of peri-implant probing depth (PIPD), modified Gingival Index (MGI), and vertical bone loss was performed at the time of prosthetic loading and 6 and 12 months later. The implant stability quotient (ISQ) was also assessed 6 and 12 months after loading. RESULTS: There was no significant difference between both groups regarding PIPD values. However, a minor but significant increase from the baseline (P < .001) was observed in PIPD values in both groups after 12 months. The MGI scores at the different time intervals were very low for both groups. The mean vertical bone loss after 12 months was minimal for both groups but statistically significant from the baseline (P < .001). ISQ values for both groups after 12 months revealed a significant increase from the baseline, and group B values were significantly higher than those of group A. CONCLUSION: Within the limitations of this study, a mandibular overdenture supported by four short implants is a valid treatment modality for atrophic mandibles, and a PBM dose of 7.5 J/cm2 has a potential positive influence on implant healing and osseointegration.

Effect of surface treated silicon dioxide nanoparticles on some mechanical properties of maxillofacial silicone elastomer.

Current materials used for maxillofacial prostheses are far from ideal and there is a need for novel improved materials which mimic as close as possible the natural behavior of facial soft tissues. This study aimed to evaluate the effect of adding different concentrations of surface treated silicon dioxide nanoparticles (SiO2) on clinically important mechanical properties of a maxillofacial silicone elastomer. 147 specimens of the silicone elastomer were prepared and divided into seven groups (n = 21). One control group was prepared without nanoparticles and six study groups with different concentrations of nanoparticles, from 0.5% to 3% by weight. Specimens were tested for tear strength (ASTM D624), tensile strength (ASTM D412), percent elongation, and shore A hardness. SEM was used to assess the dispersion of nano-SiO2 within the elastomer matrix. Data were analyzed by one-way ANOVA and Scheffe test (α = 0.05). Results revealed significant improvement in all mechanical properties tested, as the concentration of the nanoparticles increased. This was supported by the results of the SEM. Hence, it can be concluded that the incorporation of surface treated SiO2 nanoparticles at concentration of 3% enhanced the overall mechanical properties of A-2186 silicone elastomer.