Stability of contour augmentation of implant-supported single crowns in the esthetic zone: One-year cone-beam computed tomography results of a comparative, randomized, prospective, two-center clinical study using two different bone grafting techniques in early implant placement.

BACKGROUND: Early implant placement with contour augmentation could provide support and volume to the hard and soft tissues. Herein, we aimed to ascertain whether freeze-dried bone allograft (FDBA) shares with deproteinized bovine bone material (DBBM) the results for esthetic outcomes for anterior teeth and stability of peri-implant facial bone thickness and height by conducting guided bone regeneration. METHODS: Forty-eight patients were randomly assigned into two groups. In the control group, autogenous bone chips was used to cover the exposed implant surface, followed by a layer of DBBM. This graft combination was then covered with two layers of collagen membrane. In the test group, the exposed implant surface was covered with FDBA, combined with the collagen membrane. During this study, the hard tissue dimensional changes were measured at 12-months post-implant loading by using cone-beam computed tomography. RESULTS: At 12 months postoperatively, all 48 implants were clinically successful. The mean thickness of facial bone walls ranged from 1.6 to 2.45 mm at the three levels of measurement in the control group and ranged from 1.6 to 2.10 mm in the test group. The mean facial vertical bone wall peak (IP-FC) after loading 1 year presented with values of 0.8 mm (range, 0.0 to 1.25 mm) and 0.5 mm (range, 0.1 to 1.1 mm) coronal to the implant platform in control and test implants, respectively. There were no significant differences in facial bone wall thickness and IP-FC between groups. CONCLUSIONS: This study demonstrated that autogenous bone chips plus DBBM or FDBA showed similar outcome of peri-implant buccal bone stability in early implant placement after 1 year.

A comparative, randomized, prospective, two-center clinical study to evaluate the clinical and esthetic outcomes of two different bone grafting techniques in early implant placement.

BACKGROUND: Early implant placement combined with simultaneous contour augmentation was able to rebuild stable facial hard-tissue and soft-tissue contours that were esthetically pleasing. The purpose of this study was to evaluate the clinical esthetic outcome, when two different bone grafting materials were used. METHODS: Forty-eight patients were randomly assigned into two groups. In the control group, autogenous bone was used to cover the exposed implant surface then a layer of deproteinized bovine bone mineral (DBBM) was added. This graft combination was then combined with a collagen membrane. In the test group, the exposed implant surface was covered with a layer of freeze-dried bone allograft (FDBA) in combination with the collagen membrane. Modified plaque index (mPI), modified sulcular bleeding index (mSBI), probing depth (PD), keratinized mucosa (KM), implant crown length (IC), distance from the implant shoulder radiographic bone-to-implant contact (DIB), pink esthetic score (PES), and white esthetic score (WES) were measured at 12-months post implant loading. RESULTS: All 48 implants were clinically successful, and no significant differences were observed in mPI, mSBI, PD, KM, IC, DIB, PES, and WES at 1-year implant loading. The mean mucosal recessions of test and control group were unchanged, 0 and -0.02 mm, respectively. The mean DIB were -0.32 and -0.21 mm in test and control implants, respectively. The mean totals of PES/WES were 15.29 and 15.33 for the test and control groups, respectively, with no significant difference between groups. CONCLUSION: This study demonstrated that autogenous bone plus DBBM and FDBA each combined with a collagen membrane both resulted in stable clinical and esthetic outcomes in early implant placement with contour augmentation after 1 year.

Effects of residual ethanol on the rate and degree of conversion of five experimental resins.

OBJECTIVES: This study examined the extent of ethanol retention in five comonomer blends of experimental methacrylate-based dental adhesives, containing (10, 20, or 30 wt.%) ethanol, after solvent evaporation, as well as observing the effect of residual ethanol and exposure duration on degree of conversion (DC). The null hypothesis that was tested was that residual, unevaporated ethanol has no effect on the rate or extent of DC of polymerized adhesive resins. METHODS: A known mass of each mixture was placed in glass wells and evaporated for 60s. The mass of the mixtures before and after evaporation was measured, allowing calculation of the gravimetric ethanol loss/retention. RESULTS: The concentration of retained ethanol increased significantly with ethanol concentration (p<0.01): 1.1-1.9 mole/L for 10% ethanol/90% comonomers, 2.2-3.5 mole/L for 20% ethanol, and 2.6-3.7 mole/L for 30% ethanol/70% comonomers. As ethanol is evaporated from solvated comonomer mixtures, the molar concentration of comonomers increases, reducing the vapor pressure of the remaining ethanol. Thus, the fractional loss of ethanol solvent decreases as the comonomer concentration increases. The DC of 10, 20, and 30 wt.% ethanol blends increased with ethanol concentration in four of the five experimental resins (p<0.05), increasing by 30-45% when 10 or 20 wt.% ethanol was added to neat resins, regardless of exposure duration. Depending on the resin system, inclusion of 30% ethanol lowered DC at 20s but increased DC after 40-60s of light exposure. SIGNIFICANCE: Since 10 and 20 wt.% ethanol-resin blends increased the DC of solvated resins by 30-45% over neat resins, the test null hypothesis is rejected. Even with prolonged evaporation, 4-9% residual ethanol concentration can remain in 90/10 (wt./wt.) comonomer-ethanol mixtures. This is thought to be because comonomers lower the vapor pressure of ethanol. This amount of residual ethanol facilitates DC but lowers the rate of polymerization.