Background: This study is designed to evaluate the potential of different formulations of hyaluronic acid (HA) to improve new bone formation in critical-size calvaria defect (CSD) when combined with a deproteinized bovine graft (DBG) material. Methods: Thirty male rats were used. A 5-mm-diameter CSD was created and three experimental groups (n = 10) were randomly assigned based on the treatments performed. Group DBG: CSD filled with a DBG; group DBG/LV: CSD filled by the combination of DBG and HA in a low-viscosity crosslinking agent; group DBG/HV: CSD filled by the combination of DBG and HA in a high-viscosity crosslinking agent. Animals were euthanized 30 days postoperatively. Histological, histometric (percentage of newly formed bone [PNFB], percentage of remaining graft particles, histochemical, and immunohistochemical (bone morphogenetic protein 2/4 [BMP2/4], osteocalcin [OCN], and tartrate-resistant acid phosphatase [TRAP]) analyses were performed. Results: The highest PNFB was observed in DBG/HV when compared with the other groups (P ≤0.05). DBG/LV and DBG/HV presented almost no inflammatory cells. In contrast, inflammation was observed in group DBG. Extensive resorption of graft particles was observed in group DBG, which was not present in DBG/LV and DBG/HV as confirmed by the larger size of the particles (P ≤0.05). BMP2/4 and OCN immunolabeling were higher in DBG/HV when compared with group DBG (P ≤0.05). Increased number of TRAP-positive cells was observed in DBG/LV and DBG/HV (P ≤0.05). Lower percentage of mature collagen fibers was observed in DBG/HV (P ≤0.05). Conclusion:The combination of HA in a high-viscosity crosslinking agent with DBG improves the bone repair process and increases the amount of newly formed bone towards CSDs in rat calvaria.

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Background and Objectives: In dentistry, the assessment of the histomorphometric features of periodontal (PD) and peri-implant (PI) lesions is important to evaluate their underlying pathogenic mechanism. The present study aimed to compare manual and digital methods of analysis in the evaluation of the inflammatory biomarkers in PI and PD lesions. Materials and Methods: PD and PI inflamed soft tissues were excised and processed for histological and immunohistochemical analyses for CD3+, CD4+, CD8+, CD15+, CD20+, CD68+, and CD138+. The obtained slides were acquired using a digital scanner. For each marker, 4 pictures per sample were extracted and the area fraction of the stained tissue was computed both manually using a 594-point counting grid (MC) and digitally using a dedicated image analysis software (DC). To assess the concordance between MC and DC, two blinded observers analysed a total of 200 pictures either with good quality of staining or with non-specific background noise. The inter and intraobserver concordance was evaluated using the intraclass coefficient and the agreement between MC and DC was assessed using the Bland–Altman plot. The time spent analysing each picture using the two methodologies by both observers was recorded. Further, the amount of each marker was compared between PI and PD with both methodologies. Results: The inter- and intraobserver concordance was excellent, except for images with background noise analysed using DC. MC and DC showed a satisfying concordance. DC was performed in half the time compared to MC. The morphological analysis showed a larger inflammatory infiltrate in PI than PD lesions. The comparison between PI and PD showed differences for CD68+ and CD138+ expression. Conclusions: DC could be used as a reliable and time-saving procedure for the immunohistochemical analysis of PD and PI soft tissues. When non-specific background noise is present, the experience of the pathologist may be still required.

Background. The potent anti-inflammatory and immunosuppressive properties of glucocorticoids (GCs) might influence the progression of some disorders, such as periodontitis. Hence, this study aimed to investigate the influence of dexamethasone (DEX) on the alveolar bone loss (ABL) of healthy and periodontally compromised molars in rats. Methods. Thirty male rats were randomly assigned to two groups: physiological saline solution (PSS) and DEX. The animals received subcutaneous injections of either 0.5 mL of PSS) (group PSS) or 2 mg/kg of DEX (group DEX) from one day before experimental periodontitis (EP) induction until euthanasia. EP was induced through ligature placement around the mandibular lower first molars at day 0. Contralateral molars remained unligated. Ten animals per period were euthanized on days 3, 7, and 14. Morphometric analysis was performed to access the ABL. Data were statistically analyzed with ANOVA followed by post hoc Tukey tests (P≤0.05). Results. Higher ABL was observed in both groups on days 7 and 14 than on day 3 (P≤0.05). Concerning periodontitis, higher ABL was observed in group DEX on days 3, 7, and 14 days than group PSS at the same time intervals (P≤0.05). Also, even in the contralateral unligated molars, group DEX exhibited higher ABL on days 3, 7, and 14 days than group PSS at the same time intervals (P≤0.05). Conclusions. Collectively, it can be concluded that DEX aggravates EP and induces spontaneous ABL in the healthy periodontium.

Background Strontium Ranelate (SR) presents overlapping osteoanabolic and anti-resorptive activity. However, the effects of SR on the progression of periodontitis through the alveolar bone and its potential applicability as adjunctive therapy to scaling and root planning remain poorly accessed. The aim of this study was to evaluate the effects of systemic (SR) both on the progression of experimental periodontitis (EP) and as adjunctive therapy to SRP. Material and Methods Eighty male rats were divided into four groups (n=20): EP-PSS: EP induction and systemic administration of physiological saline solution (PSS); EP-SR: EP induction and systemic administration of SR; EP-SRP/PSS: EP induction, SRP and systemic administration of PSS; EP-SRP/SR: EP induction, SRP and systemic administration of SR. Seven days after ligature placement, SRP was performed in EP-SRP/PSS and EP-SRP/SR, as well as the systemic administration of either PSS or SR were initiated and continued until euthanasia in all groups. Animals were euthanized at 7 and 30 days after the beginning of the systemic treatments. Histological, histometric (percentage of bone in the furcation [PBF]) and immunohistochemical (tartrate-resistant acid phosphatase [TRAP], Osteocalcin [OCN] and leukocyte common antigen [CD 45]) analyses were performed. Data were statistically analyzed. Results EP-SRP/PSS showed a significantly more organized pattern of the connective tissue and alveolar bone structure than EP-SRP/SR. EP-SR showed significantly higher PBF than EP-PSS, however, EP-SRP/PSS showed no difference with EP-SRP/SR at 30 days. Conclusions SR reduced the alveolar bone loss in non-treated animals and presented no standout benefits over the conventional forms of treating EP. Key words: Strontium Ranelate, periodontal disease, root planing, alveolar bone loss.