Conventional treatment for periodontal disease (PD) does not promote proper regeneration of the periodontium [1]. Therefore, the use of biomaterials in guided tissue regeneration technique has become a major focus of study. The present work utilizes a membrane composed of 60% hydroxyapatite (HAp) and 40% polycaprolactone (PCL). This formulation allows the combination of HAp bioactivity [2] with PCL mechanical properties [3], obtaining a flexible membrane with tissue integration potential. The project was previously approved by the Ethics Committee on Animal Use, #14/2012. Twelve dogs were subjected to induction of PD by production of chronic class II furcation defect on the third and the fourth premolars [4]. The animals were distributed into two groups: 1) control, which received conventional prophylaxis with daily teeth brushing and application of chlorhexidine solution twice a day for two weeks; and 2) treated, which, in addition to the periodontal prophylaxis, received the membrane between gingival flap and alveolar bone, to which it was fixed with a titanium screw. After 60 days, animals were euthanized and dental samples were harvested and fixed in formalin. They were analyzed by micro-computed tomography (MicroCT) for bone volume per total volume (BV/TV) and trabecular number, thickness and separation. Samples were processed for histology and histomorphometry, evaluating tissue inside the defect, inflammatory infiltrate and periodontal tissue regeneration. MicroCT showed a significant difference (p=0.042) for only BV/TV between control (36±0.08) and treated (0.20±0,15) groups, although no furcation defect was completely filled by bone. The standard deviation of treated group (0.748) was 3.5 times higher than control (0.213), what may have influenced the results. In both groups, defect was filled by organized connective tissue with diffuse spots of inflammatory infiltration. Bone formation was restricted to the apical edge of the defect, in which provisional matrix, active osteoblasts and newly formed bone matrix could be observed.
Moreover, the formation of a homogeneous laminar matrix along the tooth root was seen in some areas, where cementum is normally found but it was scraped off during the induction protocol.
Cementum regeneration occurs by proliferation of its cellular portion located in the apical third of the root. Therefore, cementoblasts produce a matrix that is replaced by Sharpey fibers, regenerating periodontal ligament [5]. However, natural occurrence of periodontal regeneration is limited [6] and, in this study, the membrane cannot be implied in favoring these events, because the laminar matrix formation was similar in both groups. The main difference related to treatment was the greater proliferation of connective and gingival epithelial tissues in control group. In treated group, the membrane may have limited tissue proliferation, but did not prevent the epithelial invasion, which is not desirable in guided tissue regeneration [7]. Also, the observed inflammatory infiltrate indicated the contamination of the membrane, probably due to a difficult adaptation to the defect area, also important for guided tissue regeneration [1]. Therefore, the HAp-PCL membrane reduced epithelial proliferation into the periodontal defect, however, did not promote a better regeneration of periodontal tissue than untreated group in the present study.
CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil; FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais; CNPq - National Counsel of Technological and Scientific Development - Brazil
References:
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