Mohammad Hamdan Alkhraisat

Perspectives and challenges in regenerative medicine using plasma rich in growth factors.

Plasma rich in growth factors (PRGF-Endoret) is an endogenous therapeutic technology that is gaining interest in regenerative medicine due to its potential to stimulate and accelerate tissue healing and bone regeneration. This autologous biotechnology is designed for the in situ delivery of multiple cellular modulators and the formation of a fibrin scaffold, thereby providing different formulations that can be widely used in numerous medical and scientific fields including dentistry, oral implantology, orthopedics, ulcer treatment and tissue engineering among others. Here we discuss the important progress that has been accomplished in this field. Furthermore, a comprehensive outlook of the intriguing therapeutic applications of this technology is presented.

Release kinetics of platelet-derived and plasma-derived growth factors from autologous plasma rich in growth factors

Many studies have evaluated the biological effects of platelet rich plasma reporting the final outcomes on cell and tissues. However, few studies have dealt with the kinetics of growth factor delivery by plasma rich in growth factors. Venous blood was obtained from three healthy volunteers and processed with PRGF-Endoret technology to prepare autologous plasma rich in growth factors. The gel-like fibrin scaffolds were then incubated in triplicate, in a cell culture medium to monitor the release of PDGF-AB, VEGF, HGF and IGF-I during 8 days of incubation. A leukocyte-platelet rich plasma was prepared employing the same technology and the concentrations of growth factors and interleukin-1β were determined after 24h of incubation. After each period, the medium was collected, fibrin clot was destroyed and the supernatants were stored at -80°C until analysis. The growth factor delivery is diffusion controlled with a rapid initial release by 30% of the bioactive content after 1h of incubation and a steady state release when almost 70% of the growth factor content has been delivered. Autologous fibrin matrix retained almost 30% of the amount of the growth factors after 8 days of incubation. The addition of leukocytes to the formula of platelet rich plasma did not increase the concentration of the growth factors, while it drastically increased the presence of pro-inflammatory IL-1β. Further studies employing an in vitro inflammatory model would be interesting to study the difference in growth factors and pro-inflammatory cytokines between leukocyte-free and leukocyte-rich platelet rich plasma.

Platelet-Rich Plasma to Improve the Bio-Functionality of Biomaterials

Growth factors and cytokines are active players in controlling the different stages of wound healing and tissue regeneration. Recent trends in personalized regenerative medicine involve using patient’s own platelet-rich plasma for stimulating wound healing and tissue regeneration. This technology provides a complex cocktail of growth factors and even a fibrin scaffold with multiple biologic effects. In the last few years, an increasing number of studies provide evidence of the potential of combining platelet-rich plasma with different biomaterials in order to improve their properties, including handling, administration, bioactivity, and level of osseointegration, among others. In this review, we discuss the use of platelet-rich plasma as an alternative, easy, cost-effective, and controllable strategy for the release of high concentrations of many endogenous growth factors. Additionally, we provide an overview of the current progress and future directions of research combining different types of biomaterials with platelet-rich plasma in tissue engineering and regenerative medicine.

Frequency of obstructive sleep apnea syndrome in dental patients with tooth wear.

STUDY OBJECTIVESnTo estimate the frequency of obstructive sleep apnea syndrome (OSAS) in dental patients with tooth wear, and to assess the role of dentists in the identification of patients at risk of OSAS.nnnMETHODSnDental patients with tooth wear and treated with occlusal splint were prospectively recruited to perform sleep study. The severity of tooth wear was established by the treating dentist before patient referral to sleep disorders unit. Sleep questionnaires, anthropometric measurements, and validated respiratory polygraphy were performed.nnnRESULTSnAll patients with dental wear were offered a sleepiness analysis. Of 31 recruited patients, 30 (77% males) participated in this study. Patients mean age was 58.5 ± 10.7 years (range: 35-90 years) and the body mass index was 27.9 ± 3.4 kg/m(2). Tooth wear was mild in 13 patients, moderate in 8 and severe in 9. The mean apnea-hypopnea index (AHI) was 32.4 ± 24.9. AHI < 5 was reported in 2 patients, AHI of 5-29 in 17, and AHI ≥ 30 in 11. A statistically significant association was found between AHI severity and tooth wear severity (Spearman R = 0.505; p = 0.004).nnnCONCLUSIONSnTooth wear could be a tool to identify those patients at risk of having OSAS. This highlights the importance of dental professionals to identify and refer patients with OSAS.

Surgical Correction of Horizontal Bone Defect Using the Lateral Maxillary Wall: Outcomes of a Retrospective Study

PURPOSEnTo report on the outcomes of a new surgical technique for the treatment of severe horizontal bone resorption that impedes the placement of dental implants.nnnMATERIALS AND METHODSnEleven patients in need of bone augmentation to reconstruct a narrow alveolar ridge were recruited for the present study. Surgical correction of the alveolar width was performed by harvesting an onlay bone graft from the lateral wall of the maxillary sinus and filling the intervening space with plasma rich in growth factors alone or mixed with autologous bone particles. A fibrin membrane was then placed to cover the surgical site before flap closure. Clinical examinations and cone-beam computed tomography were performed to analyze the safety and efficiency of an onlay bone graft from the maxilla in horizontal bone augmentation.nnnRESULTSnThe present study is the first to describe the lateral wall of the maxillary sinus as a donor site for an onlay bone graft. The healing period was uneventful, with minimal surgical morbidity. No flap exposure occurred, and analysis of the cone-beam computed tomography scans before and after (about 5 months) bone augmentation revealed a total gain of 5.4 mm in alveolar width. This permitted the placement of dental implants to support an implant-borne prosthesis.nnnCONCLUSIONSnAn onlay bone graft from the lateral wall of the maxillary sinus is a useful and safe tool for horizontal bone augmentation with minimal surgical morbidity.

Novel technique for the treatment of the severely atrophied posterior mandible.

PURPOSEnTo present a new technique for the rehabilitation of the severely atrophied mandible that avoids the need for advanced surgical reconstruction.nnnMATERIALS AND METHODSnSevere resorption in the posterior mandible was treated following a conservative approach. A novel drilling technique and vertical implant-guided bone regeneration were performed to insert extra-short implants for maximum use of the bone above the mandibular canal. A progressive loading protocol was followed for the prosthetic rehabilitation with screw-retained prostheses. During the follow-up period, surgical complications, prosthetic failures, marginal bone loss, and implant survival were monitored.nnnRESULTSnThe described conservative approach was effective in patients with residual bone height above the mandibular canal that was often less than 6 mm. No signs of sensory disturbances or nerve injury were detected during the observation period. One hundred fourteen extra-short implants were inserted in 72 patients, with a mean follow-up period of 26 months after implant insertion. The implant survival rate was 98.2% (two implants failed). Proximal bone loss was limited to 1 mm, and detailed analysis of factors influencing bone loss indicated that the increase in implant diameter was associated with a tendency toward decreased bone loss. Prosthetic complications (eg, fracture or screw loosening) were not observed in this study.nnnCONCLUSIONSnThis minimally invasive approach contributed to successful oral rehabilitation of patients with severely atrophied posterior mandibles. The development of conservative approaches will decrease the risk of surgical morbidity, save money and time, and decrease the complexity of surgery.

Effect of physicochemical properties of a cement based on silicocarnotite/calcium silicate on in vitro cell adhesion and in vivo cement degradation

A silicon calcium phosphate cement (Si-CPC) was developed to produce a composite of calcium phosphate and calcium silicate. The silicon cements prepared with low silicon (Si) content were composed of crystalline phases of brushite and silicocarnotite. However, the cements prepared with high Si content were mainly composed of amorphous phases of silicocarnotite, hydroxyapatite and calcium silicate. The cement porosity was about 40% with a shift of the average pore diameter to the nanometric range with increasing Si content. Interestingly, this new cement system provides a matrix with a high specific surface area of up to 29 m(2) g(-1). The cytocompatibility of the new Si-doped cements was tested with a human osteoblast-like cell line (MG-63) showing an enhancement of cell proliferation (up to threefold) when compared with unsubstituted material. Cements with a high silica content also improved the cell attachment. The in vivo results indicated that Si-CPCs induce the formation of new bone tissue, and modify cement resorption. We conclude that this cement provides an optimal environment to enhance osteoblast growth and proliferation that could be of interest in bone engineering.

Minimizing the mandibular advancement in an oral appliance for the treatment of obstructive sleep apnea

OBJECTIVEnIn the treatment of obstructive sleep apnea (OSA) with an oral appliance (OA), there is no gold standard method to fine-tune the mandibular advancement. This study aimed to analyze the effect of gradual increment of mandibular advancement on the evolution of the apnea-hypopnea index (AHI).nnnMETHODSnOSA patients were recruited from a sleep unit. All treatments started with an oral appliance without mandibular advancement. After two weeks, the AHI was assessed with respiratory polygraphy. Mandibular advancement was initiated with a step size of 1xa0mm and evolution in the AHI was assessed. The target protrusion was the one that achieved the highest reduction in AHI and the least side effects. Anthropometric data, sleep questionnaire and Epworth sleepiness scale score were obtained.nnnRESULTSnThirty six patients (22 men) participated in this study. The patients mean age was 57xa0±xa012 years and the body mass index was 25.4xa0±xa04.1xa0kg/m2. The oral appliance reduced the AHI from 20.8xa0±xa012.9/h to 8.4xa0±xa05.1/h (Pxa0=xa00.000). Ten of the 26 patients with ≥50% reduction in AHI (39%) had zero advancement. The mean mandibular advancement was 1.7xa0±xa01.5xa0mm achieving ≥50% reduction in AHI in 72% of the patients. Twenty seven patients had an AHI <10/h. Of the 21 patients with moderate-severe OSA, 17 had the highest decrease in the AHI in a mandibular advancement ≤3xa0mm.nnnCONCLUSIONSnMonitoring the subjective symptoms of the patient and objective evolution in the AHI could minimize the mandibular advancement needed for the treatment of OSA.

Validation of a new domiciliary diagnosis device for automatic diagnosis of patients with clinical suspicion of OSA

Obstructive sleep apnoea is a prevalent and considerably underdiagnosed disease. The development of cost‐effective, home‐based, automatic diagnostic devices to improve the diagnosis accessibility is therefore essential.

Is Alveolar Ridge Split a Risk Factor for Implant Survival

PURPOSEnThere is a paucity of studies that have assessed the long-term outcomes of the alveolar ridge split (ARS). This study evaluated the intraoperative and postoperative complications and assessed the placed dental implant and prosthesis.nnnMATERIALS AND METHODSnA retrospective study of the ARS was conducted in a single private dental clinic. The predictor variable was the ARS technique (1 stage vs 2 stages). The primary outcome was the dental implant survival rate. Secondary outcomes were intraoperative complications, marginal bone loss, prosthetic complications, and prosthesis success rate. Descriptive analysis was performed for patients demographic data, implant details, and prosthetic complications. The Kaplan-Meier method was used to assess implant survival rate and prosthesis success rate.nnnRESULTSnTwenty patients (mean age, 55 ± 6xa0yr) had a mean follow-up time of 5xa0years. Delayed implant placement was performed when the residual alveolar bone width was narrower than 3xa0mm. No intraoperative or postoperative complications were reported. The survival rate of the 31 implants was 100% and the prosthesis success rate was 96.8%.nnnCONCLUSIONSnThe ARS is an effective technique for horizontal bone augmentation in the mandible. Delayed dental implant placement when the alveolar bone width is narrower than 3xa0mm could minimize the risk of buccal wall fracture.