Among the numerous functions of melatonin, the control of survival and differentiation of mesenchymal stem cells (MSCs) has been recently proposed. MSCs are a heterogeneous population of multipotent elements resident in tissues such as bone marrow, muscle, and adipose tissue, which are primarily involved in developmental and regeneration processes, gaining thus increasing interest for tissue repair and restoration therapeutic protocols. Melatonin directly accelerated the differentiation of human stem cells into osteoblasts and also suggested that melatonin could be applied as a pharmaceutical agent to promote bone regeneration. Inflammatory cytokines and adipokines, proangiogenic/mitogenic stimuli, and other mediators that influence the differentiation processes may affect the survival and functional integrity of these mesenchymal precursor cells. In this scenario, melatonin seems to regulate signaling pathways that drive commitment and differentiation of MSC into osteogenic, chondrogenic, adipogenic, or myogenic lineages. Common pathways suggested to be involved as master regulators of these processes are the Wnt/β-catenin pathway, the mitogen-activated protein kinases and the, transforming growth factor-β signaling. In this respect, melatonin emerges a novel and potential modulator of MSC lineage commitment and adipogenic differentiation. This review recognizes and critically examines the available information on the effect of melatonin as a regulator of MSC differentiation and protection in different organs and tissues.

Introduction: To accelerate the process of restoring dental implants, achieving primary stability is of prime importance for effective osseointegration. The various bone substitute materials such as autograft (golden standard), allograft, xenograft, and alloplast are used to improve the stability of an implant and also as an aid in bone formation. The use of bone cements, among the alloplast material, is a relatively new premise in oral implantology. These have been extensively used in orthopedic surgery to secure an implanted prosthesis and to replace or bind bone fragments, resulting from trauma, and to fill cavities. This article aims to review the literature for the use of bone cements in oral implantology and evaluate its prospective use in future to secure dental implants. Materials and Methods: PubMed search was carried out using keywords such as “Bone Cements,” “Oral Implantology,” “Cements Fix Implants with Bone,” and “Cements to Grow Bone.” Of the 1422 articles, 1015 were selected after eliminating the duplicates. After applying the inclusion and exclusion criteria, 383 abstracts were assessed for relevance, of which 17 full-text articles were selected. Five articles were excluded with reasons and 12 eligible articles were included in the systematic review. Results: Eight studies out of the 12 concluded that bone cement could be a viable alternative to allogenic or other graft materials tested. Four articles were inconclusive or showed no significant difference. However, the quality of available evidence was poor as 10 out of the 12 studies were animal trials and 2 were in vitro studies. Due to considerable heterogeneity of data, meta-analysis could not be done. Conclusion: Bone cements can be considered a possible alternative to the existing graft materials. However, further research including controlled trials with human subjects needs to be undertaken to establish its potential.

Purpose: This study aimed to compare the effect of two different implants' position (lateral incisors and canine areas) to retain mandibular complete overdenture on the ridge base contact relation after 6 months of overdenture use. Materials and Methods: Ten completely edentulous patients were selected from the Outpatient Clinic of Removable Prosthodontics Department, Faculty of Dentistry, Mansoura University. According to the position of implant placement, patients were randomly classified into two equal groups; Group I where two implants were placed in the lateral incisors' area and Group II where two implants were placed in the canines' area. Positioner attachment was connected to the implant fixture to retain the mandibular implant overdenture. Periodic monitoring of ridge base contact relation was carried out at the time of insertion (T0) and 6 months (T6) later using cone-beam computed tomography (the dual scan technique procedures). Results: There was a statistically insignificant difference between the two groups (lateral incisors' position group and canines' position group) regarding the ridge base contact relationship. Conclusion: Within the limitations of this study (patient number and study period), the ridge base relationship of two implants retained mandibular overdenture is maintained regardless of the implants' position.

Aim: The aim was to evaluate and compare retention forces of all-zirconia (ZrO₂), all-polyetheretherketone (PEEK), and ZrO₂-PEEK Computer-Aided-Designing computer-Aided -Manufacturing (CAD-CAM) telescopic attachments for two implant-retained mandibular overdentures. Materials and Methods: Fifteen identical acrylic resin models of the edentulous mandibular arch without alveolar undercuts were fabricated. Two implants were inserted in the canine region of each model. According to the material of telescopic attachment, models were divided into three groups: all ZrO₂ (ZZ): primary and secondary crowns were made of ZrO₂, all PEEK (PP): primary and secondary crowns were made of PEEK, and ZrO₂-PEEK (ZP): primary crowns were made of ZrO₂ and secondary ones were made of PEEK. Identical experimental overdentures were constructed for all models. For measuring the retention force, a universal testing machine was used to apply a pull-off test in presence of artificial saliva between the crowns. The achieved maximum values of retention force were recorded at the beginning of the study (initial retention) and after 540 cycles of insertion and removal simulating 6 months of the clinical service (final retention). Results were statistically analyzed, analysis of variance (P < 0.05). Results: ZP group reported the highest initial force values for all groups. The final retention values of PP and ZP groups were significantly decreased than initial values, while the insignificant loss of retention was observed with ZZ group (P = 0.06). Independent samples test showed a significant difference in both initial and final retentions between each two groups. Conclusion: Within the limitations of this study, ZrO₂ is more preferred as a secondary telescopic crown against a primary ZrO₂ one. Despite the loss of retention by time, PEEK can still be used as a secondary telescopic crown against ZrO₂ or PEEK primary crowns regarding the acceptable initial and final retention values.

Purpose: The aim of this study was to assess and evaluate the retention of conventional retentive sleeve material versus retention.sil in implant-retained overdentures. Methodology: Custom-designed models of uniform dimensions were made from heat-polymerized polymethyl methacrylate resin. The model had two components which comprised a lower member (matrix) and an upper member (patrix). The lower member (matrix) was embedded with two ADIN implant analogs attachment (Adin Implant System Ltd. Israel) of 3.75 mm × 10 mm with prefabricated ball attachment at an interimplant distance of 20 mm. The upper member was prepared to receive two different retention sleeve materials, conventional retentive/plastic sleeve attachment (Adin Implant System Ltd. Israel), and retention.sil 600 (Bredent medical GmbH and Co. KG). Using a universal testing machine, each of the models was subjected to 100 pulls each to dislodge the upper member from the lower member, and the force values as indicated on the digital indicator were tabulated. Statistical Analysis Used: Statistical analysis comprised Kolmogorov–Smirnov test, Friedman test, Mann–Whitney test, and Wilcoxon signed-rank test. Results: The statistical model revealed that when subjected to vertically directed forces, the conventional retentive/plastic sleeve attachment (Adin Implant System Ltd. Israel) developed higher retentive force as compared to the retention.sil 600 (Bredent medical GmbH and Co. KG). Conclusions: The conventional retentive sleeve material maintains their retentive capacity longer than the retention.sil 600. Further research is required to increase the retentive force in retention.sil material, thereby increasing denture retention and stability.

Aim: Immediate placement of an implant into the fresh extraction socket often leaves a space between the implant periphery and the surrounding bone, and the space between the implant and the bone is required to be filled with a biocompatible material such as a graft. This study aimed to compare the efficacy of synthetic bioactive glass allograft and dried freeze bovine bone grafts in the immediate implant site. Materials and Methods: The study comprised a total of thirty individuals in the age group between 16 and 60 years with at least one tooth indicated for extraction. The thirty participants were further divided into two groups. Group A comprised 15 participants who underwent extraction and buccal plate preservation (BPP), followed by immediate implant placement using synthetic allograft material (PerioGlas). Group B comprised 15 participants who underwent extraction and BPP, followed by immediate implant placement using xenograft as the graft material (Bio-Oss). The participants were evaluated both clinically and radiographically for 3 months, 6 months, and 1 year. The level of significance was set at P < 0.05. Results: PerioGlas and Bio-Oss in immediate implant site showed excellent osseointegration around the immediate implant site. However, the difference between the groups was not statistically significant. Conclusion: Both synthetic allograft and bioresorbable xenograft are promising and equally potential in bone formation around the immediate implant site.

The immediate load procedures in immediate implants have become routine in dental offices because of high esthetics demand by clients. Nevertheless, in some cases, it is not possible to perform immediate load procedures. The purpose of this article was describing the technique for creating a customized healing abutment to preserve the contours of peri-implant soft tissues and maximize peri-implant esthetics in immediate implants when it is not possible to place provisional crowns directly onto the implant. This technique is simple and easily performed and is an interesting alternative treatment for maintaining the stability of the peri-implant tissues while the osseointegration time.

Rehabilitation of edentulous posterior maxillary regions by means of implant placement often poses challenging situations due to inadequate alveolar ridge height and poor bone quality. Since resorption of posterior residual ridge is caused by sinus pneumatization or traumatic extractions, maxillary sinus floor elevation (SFE) and bone augmentation with graft materials remains the method of choice. This scientific, evidence-based, preprosthetic procedure is a corrective technique available for almost two decades in such surgically compromised cases. In this article, we will discuss and review instrumentation by lateral window approach for SFE in conjunction with bone augmentation for delayed implant placement postgraft maturation in the healing period.