Characterization of a Local Renin-Angiotensin System in Rat Gingival Tissue

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

An alternative technique to the harvesting of a connective tissue graft from a thin palate: Enhanced wound healing

This article describes an alternative surgical approach to the harvesting of subepithelial connective tissue grafts from thin palates. A partial-thickness flap is raised, and a graft composed of epithelium and connective tissue is removed from the palate. The superficial layer ( epithelium and a thin zone of connective tissue) is then dissected from the graft and replaced at the donor site to facilitate faster healing. The subjacent layer of connective tissue is placed as needed to obtain root coverage. The clinical application of this technique is described in two patients with multiple gingival recessions.

Periodontal tissue response to coverage of root cavities restored with resin materials: A histomorphometric study in dogs

Background: the purpose of this study was to histomorphometrically evaluate the response of periodontal tissues covering Class V resin restorations in dogs.Methods: After raising a mucoperiosteal flap, bony defects measuring 5 x 5 mm were created on the buccal aspect of the canines of five dogs followed by cavity preparations on the root surface measuring 3 x 3 x 1 mm. Before repositioning the flap to cover the bone defect, the cavities were restored with composite resin (CR) or resin-modified glass ionomer cement (RMGIC) or were left unrestored as control (C). The dogs were euthanized 90 days after surgery. Specimens comprising the tooth and periodontal tissues were removed, processed routinely, cut into longitudinal serial sections in the bucco-lingual direction, and stained with hematoxylin and eosin (H&E) or Masson's trichrome. The most central sections were selected for histomorphometric analysis.Results: Histomorphometric analysis revealed apical migration of epithelial tissue onto the restorative materials (RMGIC and CR). The C group presented significantly longer connective tissue attachment (P < 0.05) than the RMGIC and CR groups and significantly higher bone regeneration (P < 0.05) compared to the RMGIC group. Histologically, the cervical third (CT) of all groups had the most marked chronic inflammatory infiltrate.Conclusions: Within the limits of this study, it can be concluded that the restorative materials used exhibit biocompatibility; however, both materials interfered with the development of new bone and the connective tissue attachment process.

Biocompatibility evaluation of alendronate paste in rat's subcutaneous tissue

Alendronate is a known inhibitor of root resorption and the development of alendronate paste would enhance its utilization as intracanal medication. Therefore, this study aimed to investigate the biocompatibility of experimental alendronate paste in subcutaneous tissue of rats, for utilization in teeth susceptible to root resorption. The study was conducted on 15 male rats, weighing similar to 180-200 grams. The rats' dorsal regions were submitted to one incision on the median region and, laterally to the incision, the subcutaneous tissue was raised and gently dissected for introduction of two tubes, in each rat. The tubes were sealed at one end with gutta-percha and taken as control. The tubes were filled with experimental alendronate paste. The animals were killed at 7, 15 and 45 days after surgery and the specimens were processed in laboratory. The histological sections were stained with hematoxylin-eosin and analyzed by light microscopy. Scores were assigned to the in. ammatory process and statistically compared by the Tukey test (P < 0.05). Alendronate paste promoted severe inflammation process at 7 days, with statistically significant difference compared to the control (P < 0.05%). However, at 15 days, there was a regression of in. ammation and the presence of connective tissue with collagen fibers, fibroblasts and blood vessels was observed. After 45 days, it was observed the presence of well-organized connective tissue, with collagen fibers and fibroblasts, and few in. ammatory cells. No statistical difference was observed between the control and experimental paste at 15 and 45 days. The experimental alendronate paste was considered biocompatible with subcutaneous tissue of rat.

Evaluation of tissue response to periodontal dressings: Histological study in tooth sockets of rats

Although the use of periodontal dressings is currently limited, there are some indications for their use. Selection of any material that will have direct contact with live tissues, such as periodontal dressings, should be careful in order to allow surgical wound healing. The aim of this study was to evaluate the intensity of inflammatory response and bone formation in tooth sockets of rats after implantation of three periodontal dressings. After removal of the right maxillary incisors of 84 male rats, each tooth socket received implantation of a polyethylene tube, 63 of which were filled with non-eugenol periodontal dressing and the remaining 21 tubes remained empty (control group). Histological evaluation assessed the intensity of inflammatory response and presence and location of bone tissue formation at postoperative periods of 7, 14 and 28 days. Statistical analysis was performed by the Kruskal-Wallis test at 5% significance level. Regarding the inflammatory infiltrate, at 28 days, there was statistically significant difference between one of periodontal dressings and control group (p < 0.05). Analysis of postoperative periods, showed that the control group presented statistically significant reduction in the inflammatory infiltrate comparing the 14- and 28-day periods (p < 0.05). Regarding bone tissue formation, there was difference in control group between the 7- and 28-day periods (p < 0.05). Within the experimental conditions, it may be concluded that no differences were found in the inflammatory response among the groups at 7 and 14 days and that Voco pac (TM) dressing induced a more intensive inflammatory reaction at 28 days.

Nicotine-Induced Damage Affects Gingival Fibroblasts in the Gingival Tissue of Rats

Background: Very limited information is available from in vivo studies about whether smoking and/or nicotine affect gingival tissues in the absence of plaque. The purpose of this study is to evaluate the effect of the systemic administration of nicotine in the proliferation and counting of fibroblast-like cells in the gingival tissue of rats.Methods: Thirty adult male Wistar rats were randomly assigned into two groups to receive subcutaneous injections of a saline solution (control group = group C) or nicotine solution (group N; 3 mg/kg) twice a day. The animals were euthanized 37, 44, or 51 days after the first subcutaneous injection. Specimens were routinely processed for serial histologic sections. Five fields of view in the connective tissue adjacent to the gingival epithelium and above the alveolar bone crest of the maxillary first molar were selected for the counting of fibroblast-like cells. Data were statistically analyzed (P<0.05).Results: The intergroup analysis detected a lower number of fibroblast-like cells in group N compared to group C on days 37 (2.65 +/- 1.41 and 6.67 +/- 3.25, respectively), 44 (2.70 +/- 1.84 and 8.57 +/- 2.37, respectively), and 51(2.09 +/- 1.41 and 7.49 +/- 2.60, respectively) (P<0.05). The quantification of fibroblast-like cells showed no significant difference (P >0.05) in the intragroup analysis of control and nicotine throughout experimental periods. In the intergroup analysis, group N had reduced proliferating cell nuclear antigen positive fibroblasts compared to group C in all periods (P<0.05).Conclusion: The daily systemic administration of nicotine negatively affected, in vivo, the number and proliferation of fibroblast-like cells in the gingival tissue of rats. J Periodontol 2011;82:1206-1211.

Clinical and histological evaluation of subepithelial connective tissue after collagen sponge implantation in the human palate

Rocha AL, Shirasu BK, Hayacibara RM, Magro-Filho O, Zanoni JN, Araujo MG. Clinical and histological evaluation of subepithelial connective tissue after collagen sponge implantation in the human palate. J Periodont Res 2012; 47: 758765. (c) 2012 John Wiley & Sons A/S Background and Objective: Successful root-coverage treatment depends on the thickness of the donor tissue. This study aimed to evaluate the thickness of donor tissue after augmentation of the connective tissue in the palatal area by implantation of lyophilized collagen sponge (Hemospon (R)). Material and Methods: Ten patients with an indication for root coverage, whose palate was deficient in adequate connective tissue, were recruited. The procedure was carried out in two stages. In the first stage, the palatal thickness in the donor site was measured at three standardized points (points 1, 2 and 3), from the distal of the canine to the distal of the first molar, and the lyophilized collagen sponge was inserted. In the second stage, the palatal thickness over the implant was measured (at points 1, 2 and 3), two biopsies of the palatal mucosa were collected one over the implant (experimental sample) and the other on the contralateral side (control sample) and then root-coverage treatment was performed. Analyses consisted of clinical assessment of the palatal measurements before and after sponge implantation, and histological assessment of the experimental and control biopsy samples. Data were analyzed using the Wilcoxon test. Results: Both analyses showed a significant increase in mean thickness, of 1.08 mm of neoformed tissue in the clinical analysis (the tissue at point 2 was the thickest of the three points) and of 0.53 mm in the histological analysis. Conclusion: The insertion of lyophilized collagen sponge induced a significant increase in the thickness of palatal connective tissue.

Digital Radiographic Evaluation of the Level of Alveolar Bone Crest in External Hexagon Implants Submitted to 2 Types of Implant Abutments Under Immediate Loading

Purpose: The aim of this study was to evaluate by means of digital radiography the behavior of the alveolar bone crest in external hexagon implants following the use of 2 different types of abutments, one for conventional cemented prosthesis and one for modified cemented prosthesis.Methods: Ten external hexagon implants (platform 4.1) were placed in 5 patients. Initial instrumentation was carried out to obtain primary stability of the temporary prostheses under immediate loading. Each patient received both abutments for conventional and modified cemented prosthesis. Standardized digital periapical radiographies were performed at times T0 (immediately after implant placement) and T1 (4 months after implant placement). A straight line was initially established from the implant platform to the distal and mesial periimplantar marginal bone tissue (immediately in contact with the implant) and measured by digital radiography, using Sidexis version 2.3 (Sirona Dental Systems GmbH, Bensheim, Germany) software. The data were submitted to paired-samples t-test analysis.Results: There was no significant difference between the conventional and modified cemented prosthesis. In both cases, t-test results were within the null hypothesis level.Conclusion: The abutment for the modified cemented prosthesis resulted in no significant radiographic difference of alveolar bone crest height, when compared with the conventional cemented prostheses.

Use of the connective tissue graft for the coverage of composite resin-restored root surfaces in maxillary central incisors

The purpose of this article is to report the use of the subepithelial connective tissue graft technique combined with the coronally positioned flap on a composite resin-restored root surface to treat Miller Class I gingival recessions associated with deep cervical abrasions in maxillary central incisors. Clinical measurements, including gingival recession height, probing depth, and bleeding on probing (BoP), were recorded during the preoperative clinical examination and at 2, 6, 12, and 24 months postoperatively. During the follow-up periods, no periodontal pockets or BoP were observed. The periodontal tissue of the teeth presented normal color, texture, and contouring. In addition, it was observed that creeping attachment had occurred on the restoration. This case report shows that this form of treatment can be highly effective and predictable in resolving gingival recession associated with a deep cervical abrasion. (Quintessence Int 2012;43:597-602)