Explantation Site Management: A Decision Algorithm for Re-Implantation.

Dental implants are currently the preferred choice to restore function and esthetics. Nonetheless, explantation is sometimes inevitable in cases with advanced bone loss, implant fracture, or improper implant position. This study aimed to propose an algorithm for reimplantation at sites of previous failure. There is limited evidence on the replacement of failed implants, most of which are case reports or clinical trials with a small number of patients. To the best of the authors' knowledge, this is the first study proposing a clinical-decision algorithm to help clinicians manage implant failures with new implants. There are a variety of reasons contributing to implant failure: The etiologic factor of failure and the morphology of the residual defect have paramount importance on implant removal techniques and subsequent treatment modalities. There is no consensus on a distinct protocol to replace failed implants. However, the clinicians and patients should know that placing a new implant in an area with a history of failure, regardless of early or late implant failure, may have a lower survival rate.

Effect of Implant Design on Stress Distribution: A Finite Element Study.

Implant design and biomaterial composition are contributing factors in stress distribution throughout the implant body and the surrounding bone. The aim of this study was to evaluate the pattern of stress distribution using four different implant systems based on finite element analysis. This study was conducted using a cone beam computed tomography scan and four implant systems (ITI, SPI, 3i, and IDCAM); mandibular and implant models were constructed by a computer-aided design software (CATIA). Stress distribution under axial, mesio-distal, and combination static loading was assessed using finite element analysis in ABAQUS. The maximum von Mises stress value in dental implants was recorded for IDCAMs and IDCAMm implants considering all types of loading directions; however, these implant models showed the least stress distribution in the surrounding bone. The maximum stress occurred using combination followed by axial and mesio-distal loading. The stress distribution was concentrated, in all designs, at the level of the most coronal portion of the cortical bone. Within the limitations of the present study, it could be assumed that implant design may affect the distribution of stress in the implant body, and it could be used as a strategy to reduce stress concentration in the surrounding bone.

Lip repositioning with or without myotomy: a systematic review.

Excessive gingival display is an esthetic issue that is commonly managed by different procedures. Lip repositioning is a modality to address concerns of affected patients. The aim of this review was to investigate the scientific evidence on outcomes and long-term stability of lip repositioning surgery with or without myotomy. The electronic search was conducted in three databases: MEDLINE, Embase, and the Cochrane Library up to October 2019. No publication status, language, or time restrictions were applied. The electronic search was complemented by a manual search of the reference lists. Three hundred thirty-eight studies were screened by title, and 16 articles remained for data extraction. The included studies assessed the lip repositioning procedure in 144 patients aged between 15-59 years (134 females and 10 males). Based on the available data, lip repositioning with myotomy/muscle containment can be a successful treatment for minor discrepancies in gingival display in selected cases. However, further well-organized controlled clinical trials are recommended to derive a conclusion about the long-term stability compared with other alternatives.

Effects of leukocyte-platelet-rich fibrin and advanced platelet-rich fibrin on the viability and migration of human gingival fibroblasts.

BACKGROUND: Platelet products play a fundamental role in the process of healing. The new generation of platelet-rich fibrin (PRF), namely advanced PRF (A-PRF), has different biological and mechanical properties compared to those of leukocyte-PRF (L-PRF). This study aimed to compare the effects of L-PRF and A-PRF on the viability and migration of human gingival fibroblasts (HGFs). MATERIALS AND METHODS: In this in vitro study, the effects of A-PRF and L-PRF on the viability and migration of HGFs after 24 and 48 h were evaluated using the methyl thiazolyl tetrazolium assay. The viability of the negative control culture medium was considered to be 100%. The mean optical density of the test groups was divided by that of the negative control group and reported as percentage. One-way ANOVA was applied to assess the effects of time and type of PRF on the viability and migration of HGFs. Pairwise comparisons were made using the Tukey's test. RESULTS: At 24 h, cell viability in the L-PRF group was significantly higher than that in the A-PRF group (P < 0.05). However, no significant difference was noted between the two groups at 48 h. At 24 h, L-PRF caused significantly higher cell migration compared to the negative control group, whereas at 48 h, both A-PRF and L-PRF significantly increased cell migration compared to the control group. CONCLUSION: Within the limitations of this study, L-PRF and A-PRF had significant effects on the viability and migration of HGFs. Further studies on these platelet concentrates are warranted.