Journal of Dental Medicine

The Guided Bone Regeneration (GBR) treatment concept advocates that regeneration of osseous defects is predictably attainable via the application of occlusive membranes, which mechanically exclude non-osteogenic cell populations from the surrounding soft tissues, thereby allowing osteogenic cell populations originating from the parent bone to inhabit the osseous wound. The use of membrane to exclude non-osteogenic cells, is a key principle of guided bone regeneration. A large number of membranes have been evaluated in clinical and experimental studies. The object of this study was to review the literature regarding guided bone regeneration and all types of membranes that were used in this technique. 72 articles between the years 1968 through the 2016 from PubMed, Medline and Google Scholar using the related keywords, were selected. Finally, we concluded that the modification of mechanical and physico-chemical properties of membranes could improve the process of new bone growth. However, determination of the exact role of membrane porosity in this process, still needs to be clarified. Optimization the chemical composition of membrane with the focus and attention to obstructive property and bioactivity, is an important point in this research field. Various factors such as flexibility, mechanical strength and degradation rate determine the type of membrane used for bone tissue regeneration.

Background and Aims: Reconstruction of osseous defects is one of the ideal goals of periodontal treatments and dental implant therapy. Different biomaterials have been used for this purpose and many studies have tried to compare and introduce the best ones. The present study aimed to evaluate the effect of PDFDB (Partially Demineralized Freeze-Dried Bone Graft) and FDBA (Freeze Dried Bone Allograft) on the regeneration of rabbit calvarial defects.
Materials and Methods: In this experimental study, 48 similar defects with the diameter of 8 mm were generated in the calvarium of 16 rabbits. Two defects were filled with FDBA and PDFDB, while the other one remained unfilled as the control group. All defects were covered by collagen membranes. 6 and 12 weeks after surgery, the histologic and histomorphometric tests were performed to evaluate the following variables: the rate of new bone formation and its type, the amount of residual grafting material, degree of inflammation and pattern of bone formation. Comparison of osteogenesis percentage and residual biomaterial was performed by repetitive variance analysis, whereas qualitative variables were compared by Friedman non-parametric test.
Results: Regarding bone formation percentage, there was no statistically significant difference between three different groups at 6-week (P=0.33) and also at 12-week time points (P=0.98). The amount of residual material in the PDFDB group was significantly lower than FDBA (P=0.04) in the 6-week samples. However, this difference was not significant in the 12-week samples (P=0.41). Bone quality showed statistically significant difference between graft containing groups and control group after 12 weeks (P=0.01). It means, all samples in FDBA and PDFDB groups displayed lamellar bone after 12 weeks while in control group, only woven bone or a combination of woven and lamellar bone was seen.
Conclusion: FDBA and PDFDB demonstrated similar regenerating effect in the rabbit calvarial bone defects and hastened bone maturation compared to the non-grafted defects.

Background and Aims: Immediate implant placement following tooth extraction is a treatment with many advantages. Alveolar bone preservation after immediate implant, need minimum of 2 mm thickness in buccal bone plate. The aim of this study was to evaluate the thickness of buccal cortical bone of maxillary premolars by Cone Beam Computational Tomography (CBCT) technique.
Materials and Methods: In this descriptive epidemiological study, Cone Beam Computed Tomography image was obtained from 29 patients (male and female) referred to the radiology department of Jundi Shapoor dental school of Ahvaz from 1393 (Mehr) to 1394 (Shahrivar) for implant insertion insertion. The thickness of buccal cortical bone was measured in 3 and 5 mm apical to the CEJ and root apex, perpendicular to the longitudinal axis. All the measurements were done by two oral and maxillofacial radiologists, separately. Data were analyzed by SPSS22 software, using descriptive statistics, and T-test.
Results: The thickness of buccal cortical bone in second premolar was significantly more than 1 mm (P=0.001), but in first premolar, the thickness was close to 1 mm with a non-significant difference (P=0.29).
Conclusion: The results of this study showed that immediate implant insertion could be done in the maxillary second premolar area with more predictability compared to the first premolar area.

Guided bone and tissue regeneration is a common technique used in the treatment of areas around teeth and dental implants. In this framework, barrier membranes are employed to create a suitable environment that promotes new bone growth while preventing the invasion of foreign cellular components into this specific setting. Attributes such as biocompatibility with living tissues, structural integrity, longevity, and user-friendliness constitute the principal criteria for selecting appropriate membranes for this particular application. Given the extensive diversity of membrane types concerning their sources, texture, architecture, and inherent properties, determining the most suitable variant depends on the clinical condition presented by the patient and the specific treatment modality, thereby emphasizing its considerable importance. In recent years, fibrous membranes have garnered particular attention due to their distinctive characteristics. These membranes, made of natural or synthetic fibers, typically exhibit high porosity, which facilitates the ingress of vascular structures and osteogenic cells. Owing to their porosity and flexibility, fibrous membranes are considered exceptionally suitable for the regeneration of maxillofacial and dental tissues, thereby contributing to increase bone volume, guide its growth, and at the same time prevent soft tissue encroachment into the restoration area, which ultimately has a favorable effect on treatment outcomes. On the other hand, due to the complexity and extent of oral infections, new nanotechnological approaches have been proposed in recent years to reconstruct infected sites in dentistry. These strategies, by targeting specific sites and having non-toxic properties, can help deliver antimicrobial molecules, regenerate tissue, and maintain oral health. In this context, nanofibrous membranes serve as multifunctional structures, both in the controlled release of antimicrobial agents and as scaffolds for the formation of nascent tissue. Overall, fibrous membranes, by mimicking the physiological conditions of the organism, create an ideal environment for the growth and healing of bone tissues, leading to improved effectiveness in dental procedures. This article is devoted in detail to a comprehensive review of polymeric and composite fibrous membranes with drug release potential.

Background and Aims: Over the past two decades, the use of mini-screws in orthodontics has become increasingly common. Various factors such as design, length, diameter, and insertion angle of the miniscrew, as well as the quality and thickness of the patient's bone, would influence the success and stability of miniscrews. This study aimed to investigate the effects of miniscrew shape, cortical and cancellous bone thickness, and insertion/removal torque on the stress distribution in the mandibular bone surrounding the miniscrew.
Materials and Methods: This study was conducted using finite element analysis (FEA). Bone thickness parameters were extracted from the literature, and the mandibular bone along with cylindrical and tapered miniscrew models were simulated using ABAQUS software. By altering the relevant variables, the resulting stress were evaluated.
Results: An increase in both insertion and removal torque led to a corresponding rise in the stress around the miniscrew. Stress variations were more pronounced in tapared miniscrews in response to the changes in bone thickness and torque. The influence of cancellous bone thickness on stress distribution was found to be minimal.
Conclusion: Although, the tapered miniscrews offer greater retention and stability compared to the cylindrical types, their heightened sensitivity to variations in parameters such as bone thickness and torque necessitates cautious application.

Background and Aims: Recently, the use of the palatal process as a source of autogenous bone graft has been considered. Given the anatomical limitations of this space, the assessment of available bone in this area can play an important role in the correct treatment plan. The aim of this study was to assess the amount and density of available bone for the preparation of autogenous graft from the maxillary palatal process using CBCT (Cone Beam Computed Tomography).
Materials and Methods: This cross-sectional analytical study was conducted by collecting CBCT images from 78 patients referred to one of the maxillofacial radiology clinics in Kermanshah in 2022 and 2023. All the patients had no signs of trauma, impacted teeth, pathological lesions, cleft palate, severe periodontitis, or extensive surgery, and also had all the teeth in the area of interest (right first premolar to left first premolar) and their bone growth was completed (age over 20 years). The CBCT images were collected and analyzed using the ondemand program. Different indices such as the area of each cross-sectional slice, bone volume (main variable) were measured with the help of mathematical formula, bone density, and incisive canal diameter. In order to test the hypotheses, the Smirnov-Kolmogorov test was used to check the normality of data, and since none of our variables were normal, we used Spearman and Mann-Whitney correlation tests.
Results: This study was conducted on 78 subjects with a mean age of 43 years, 39 of whom were female and 39 of whom were male. The mean bone volume obtained was 1.84 cm3. The highest bone density was observed in the lateral incisor region and the mean incisal canal diameter was reported to be 2.68 mm. According to the results of the Spearman test, none of the variables had a significant relationship with the age variable. According to the results of the Mann-Whitney test, there was no significant difference in bone density in the lateral, canine, and premolar tooth areas between men and women. However, available bone volume was associated with gender, and this amount was calculated to be greater in men than in women.
Conclusion: According to the findings of this study, the average bone volume in the anterior region of maxilla was 1.51 cm3 and the highest bone density was in the lateral tooth region. The average incisal canal diameter was 2.68 cm3 and the available bone volume was related to gender and this value was higher in men than that of women. However, there was no difference in the bone density between men and women.