Adel Al-Asfour

Aim: The aim of this study was to evaluate the adhesion of oral microorganisms on the surfaces of polytetrafluoroethylene (PTFE) membranes used in guided bone regeneration (GBR) procedures. Materials and Methods: In this study, three oral microorganisms (Streptococcus mutans, Porphyromonas gingivalis, and Candida albicans) were used, and six PTFE membranes were characterized by their surface roughness, contact angle (CA), and surface free energy (SFE). Microbial hydrophobicity was investigated, and adhesion was examined via DNA extraction and quantitative real-time PCR. Results: Significant differences were noted amongst the membranes with respect to SFE, CA, and roughness (p < 0.001). S. mutans was the most hydrophobic microorganism, followed by C. albicans and P. gingivalis. SEM analyses confirmed that the microorganisms adhered to all membranes, with Surgitime being the membrane that attracted the highest number of S. mutans (p < 0.001) and P. gingivalis (p < 0.001). By contrast, OsseoGuard-TXT was one of the membranes that attracted the lowest number (p < 0.001) of all three tested species. Conclusions: The results showed that microbial adhesion to PTFE membranes was affected by the membrane surface roughness and SFE, as well as the characteristics of the microorganisms. The most hydrophilic bacteria adhered the least to all the tested membranes, whereas membranes with a low surface roughness and high SFE attracted the lowest number of all the tested microbes. These results may guide the selection of an appropriate GBR membrane.

Objectives: Guided bone regeneration (GBR) is a core procedure used to regenerate bone defects. The aim of the study was to investigate the adherence of Candida albicans on six commercially available polytetrafluoroethylene (PTFE) membranes used in GBR procedures and the subsequent clinical consequences.Materials and Methods: Six commercially available PTFE membranes were tested. Two of the membranes had a textured surface and the other four a plane, nontextured one. C. albicans (ATCC 24433) was cultured for 24 h, and its cell surface hydrophobicity was assessed using a modified method. C. albicans adhesion to membrane discs was studied by scanning electron microscopy (SEM) and real‐time polymerase chain reaction (PCR).Results: C. albicans was found to be hydrophobic (77.25%). SEM analysis showed that C. albicans adherence to all membranes examined was characterized by patchy, scattered, and small clustered patterns except for one nontextured membrane with a most rough surface in which a thick biofilm was observed. Real‐time PCR quantification revealed significantly greater adhesion of C. albicans cells to PTFE membranes than the control membrane (p ≤ .001) with the membranes having a textured surface exhibiting the highest count of 2680 × 10⁴ cells/ml compared to the count of 707 × 10⁴ cells/mL on those with a nontextured one (p ≤ .001). One membrane with nontextured surface, but with most rough surface was found to exhibit the highest count of 3010 × 10⁴ cells/ml (p ≤ .05).Conclusion: The results of this study indicate that C. albicans adhesion on membranes' surfaces depends on the degree of surface roughness and/or on the presence of a texture. Textured PTFE membranes and/or membranes high roughness showed significantly more adhered C. albicans cells. These findings can impact the surgeon's choice of GBR membrane and postoperative maintenance.

Non-resorbable PTFE membranes are frequently used in dental-guided bone regeneration (GBR). However, there is a lack of detailed comparative studies that define variations among commonly used PTFE membranes in daily dental clinical practice. The aim of this study was to examine differences in physicochemical and mechanical properties of several recent commercial PTFE membranes for dental GBR (Cytoplast^TM TXT-200, permamem^®, NeoGen^®, Surgitime, OsseoGuard^®-TXT, OsseoGuard^®-NTXT). Such differences have been rarely recorded so far, which might be a reason for the varied clinical results. For that reason, we analyzed their surface architecture, chemical composition, tensile strength, Young’s modulus, wettability, roughness, density, thickness and porosity. SEM revealed different microarchitectures among the non-textured membranes; the textured ones had hexagonal indentations and XPS indicated an identical spectral portfolio in all membranes. NeoGen^® was determined to be the strongest and OsseoGuard^®-TXT was the most elastic. Wettability and roughness were highest for Surgitime but lowest for OsseoGuard^®-NTXT. Furthermore, permamem^® was the thinnest and NeoGen^® was identified as the thickest investigated GBR membrane. The defect volumes and defect volume ratio (%) varied significantly, indicating that permamem^® had the least imperfect structure, followed by NeoGen^® and then Cytoplast ^TM TXT-200. These differences may potentially affect the clinical outcomes of dental GBR procedures.

Peri-implant keratinized mucosa (PI-KM) may support implant survival. Acellular collagen matrices (aCMs) have been widely used to facilitate soft tissue regeneration. The aim of this study was to investigate clinical outcomes obtained with the use of an aCM (mucoderm^®) to enhance PI-KM. In this retrospective non-randomized case series, 27 restored implants in 14 patients (eight males and six females, mean age = 56 years) with a PI-KM width ≤ 1 mm were followed for 6 months. It was demonstrated that aCM grafts augmented PI-KM effectively (mean increase of 5.4 mm; >533%) without a significant change in bleeding on probing (BOP) from baseline. The mean aCM shrinkage was 3.9 mm (42%). Gender, area, arch, and BOP did not influence PI-KM augmentation or aCM shrinkage significantly. The present results demonstrated that the examined aCM was effective and predictable for attaining a band of keratinized tissue, while avoiding graft donor site harversting.

Guided tissue regeneration (GTR) membranes are used for treating chronic periodontal lesions with the aim of regenerating lost periodontal attachment. Spatially designed functionally graded bioactive membranes with surface core layers have been proposed as the next generation of GTR membranes. Composite formulations of biopolymer and bioceramic have the potential to meet these criteria. Chitosan has emerged as a well-known biopolymer for use in tissue engineering applications due to its properties of degradation, cytotoxicity and antimicrobial nature. Hydroxyapatite is an essential component of the mineral phase of bone. This study developed a GTR membrane with an ideal chitosan to hydroxyapatite ratio with adequate molecular weight. Membranes were fabricated using solvent casting with low and medium molecular weights of chitosan. They were rigorously characterised with scanning electron microscopy, Fourier transform infrared spectroscopy in conjunction with photoacoustic sampling accessory (FTIR-PAS), swelling ratio, degradation profile, mechanical tensile testing and cytotoxicity using human osteosarcoma and mesenchymal progenitor cells. Scanning electron microscopy showed two different features with 70% HA at the bottom surface packed tightly together, with high distinction of CH from HA. FTIR showed distinct chitosan dominance on top and hydroxyapatite on the bottom surface. Membranes with medium molecular weight showed higher swelling and longer degradation profile as compared to low molecular weight. Cytotoxicity results indicated that the low molecular weight membrane with 30% chitosan and 70% hydroxyapatite showed higher viability with time. Results suggest that this highly segregated bilayer membrane shows promising potential to be adapted as a surface layer whilst constructing a functionally graded GTR membrane on its own and for other biomedical applications.

The coronavirus disease 2019 (COVID-19) pandemic has had a significant impact on dental education worldwide. Due to the rapid spread of COVID-19 across Kuwait, it was essential for the Faculty of Dentistry (FoD) at Kuwait University to make appropriate modifications to the functioning of the dental school. The FoD’s goal was not only to ensure a safe environment for its staff, students, and patients but also to sustain the students’ academic progression. The FoD adopted several measures including the establishment of a COVID-19 response team, adoption of a blended-learning model, and phase-wise re-opening of the dental center. This paper discusses on the strategies that the FoD adopted, in response to the challenges posed by the pandemic.