Hard and soft tissue evaluation of alveolar ridge preservation compared to spontaneous healing: a retrospective clinical and volumetric analysis.

PURPOSE: The remodeling process following tooth extraction can be observed as horizontal and vertical bone reduction of the alveolar ridge. Preservation procedures such as alveolar ridge preservation (ARP) aim to maintain the 3D volume of the extraction site. This retrospective study analyzed differences in the hard and soft tissue changes in patients treated with either spontaneous healing or ARP. METHODS: After tooth extraction, the patients were treated either by spontaneous socket healing (SH group) or with ARP using a xenograft and a resorbable membrane (ARP group). One week before and 6 months after extraction, the patients underwent cone beam computed tomography. A volumetric analysis was performed by superimposing the digital models of the two time points. Intraoral radiography was performed after implant placement, upon prosthesis delivery, and at 1-year post-treatment. An esthetic assessment was conducted using the Pink Esthetic Score (PES). The patients' overall satisfaction with the implant restoration was investigated at 12 months. RESULTS: Intragroup comparisons revealed significant differences between baseline and the 6-month follow-up in both groups at the measured locations (1 mm, 3 mm, and 5 mm below the most coronal aspect of the alveolar ridge) showing a reduction of the horizontal width (P < 0.05). Additionally, after treatment, the horizontal width at 1 mm was significantly different in the SH and ARP groups (P < 0.001), with mean changes of 2.03 ± 0.54 mm and 0.86 ± 0.49 mm, respectively. ARP was associated with an increased PES (11.6 ± 2.2) and a reduction in patients requiring additional grafting procedures in subsequent treatment phases (9% vs 26%; P = 0.11). CONCLUSIONS: In both groups, significant horizontal and vertical bone loss was observed after the extraction. ARP can reduce linear and volumetric shrinkage of the alveolar ridge, leading to improved outcomes. It can also simplify implant restoration.

The Treatment of Peri-Implant Diseases: A New Approach Using HYBENX® as a Decontaminant for Implant Surface and Oral Tissues.

BACKGROUND: Peri-implantitis is a pathological condition characterized by an inflammatory process involving soft and hard tissues surrounding dental implants. The management of peri-implant disease has several protocols, among which is the chemical method HYBENX®. The aim of this study is to demonstrate the efficacy of HYBENX® in the treatment of peri-implantitis and to compare HYBENX® with other chemical agents used in the surgical treatment of peri-implantitis. METHODS: The present study included a population of ten subjects with severe peri-implantitis. The procedure used in the study involves the application of HYBENX® after open-flap debridement. Each patient has been followed for 12 months after a single application of the decontaminant agent. Clinical and radiographical parameters were recorded at baseline, 3 months, and 12 months after treatment completion. RESULTS: At baseline, a mean pocket probing depth (PPD) of 7.3 ± 0.5 mm and a mean clinical attachment level (CAL) of 8.8 ± 0.8 mm was recorded. An average residual PPD of 4.2 ± 0.5 mm and a mean CAL of 5.2 ± 0.8 mm were observed after 1 year. Additionally, the average of bone gain was about 3.4 mm, with a mean marginal bone level (MBL) change from 5.8 mm (baseline) to 2.4 mm (12 months). In total, 90% of the treated implants reached the success rate after the 1-year follow-up. Only in one case out of ten treated implants was resolution of the disease not achieved. CONCLUSION: Clinical improvements highlight that the procedure of open-flap debridement (OFD) + HYBENX® may be considered an effective technique in the treatment of peri-implantitis. From the results obtained, it can be concluded that the use of HYBENX® in the surgical treatment of peri-implantitis is promising. Overall, this protocol demands further studies to better understand the role and potential benefits of HYBENX® in the treatment of peri-implantitis.

Isotropic-nematic phase equilibria in the Onsager theory of hard rods with length polydispersity.

We analyze the effect of a continuous spread of particle lengths on the phase behavior of rodlike particles, using the Onsager theory of hard rods. Our aim is to establish whether "unusual" effects such as isotropic-nematic-nematic (I-N-N) phase separation can occur even for length distributions with a single peak. We focus on the onset of I-N coexistence. For a log-normal distribution, we find that a finite upper cutoff on rod lengths is required to make this problem well posed. The cloud curve, which tracks the density at the onset of I-N coexistence as a function of the width of the length distribution, exhibits a kink; this demonstrates that the phase diagram must contain a three-phase I-N-N region. Theoretical analysis shows that in the limit of large cutoff, the cloud point density actually converges to zero, so that phase separation results at any nonzero density; this conclusion applies to all length distributions with fatter-than-exponentail tails. Finally, we consider the case of a Schulz distribution, with its exponential tail. Surprisingly, even here the long rods (and hence the cutoff) can dominate the phase behavior, and a kink in the cloud curve and I-N-N coexistence again result. Theory establishes that there is a nonzero threshold for the width of the length distribution above which these long-rod effects occur, and shows that the cloud and shadow curves approach nonzero limits for a large cutoff, both in good agreement with the numerical results.