ALVEOLAR SOCKET PRESERVATION TECHNIQUE: HISTOLOGICAL HEALING OF HARD AND SOFT TISSUES.
Tesi di Dottorato
Data di Pubblicazione:
2012
Citazione:
ALVEOLAR SOCKET PRESERVATION TECHNIQUE: HISTOLOGICAL HEALING OF HARD AND SOFT TISSUES / G. Pellegrini ; tutor: C. Dellavia ; coordinatore: R. Weinstein. Universita' degli Studi di Milano, 2012 May 30. 24. ciclo, Anno Accademico 2011. [10.13130/pellegrini-gaia_phd2012-05-30].
Abstract:
INTRODUCTION
After tooth extraction, the use of grafting materials and absorbable membrane, alone or in association, were proposed for maintenance procedures of alveolar ridge volume. The preservation of bone volume in posterior maxillary area might be necessary to optimize the delayed implant placement without sinus augmentation procedure. In addition, importance of peri-implant soft tissue has been related to final aesthetic outcomes. The alveolar socket preservation technique may affect the healing of the overhanging mucosa.
This research is composed by two studies (A and B).
Aim of the study A was to evaluate histologically the integration and remodelling of porous bovine bone particles (PBBM) grafted in the extraction socket, and to compare the dimensional alterations of the alveolar ridge in the molar maxillary area after extraction with or without the graft of PBBM particles, at medium and advanced endpoints.
Aim of the study B was to histologically compare soft tissue features of augmented alveolar sockets covered or not covered with collagen membrane.
Methods
Study A: This is a randomized double-blind controlled clinical trial. Sixteen patients who needed the extraction of one maxillary molar tooth were included in the study. After extraction seven sites were treated with PBBM particles (Bio-Oss Collagen) covered with collagen membrane (test), and nine sites were left untreated as control. At baseline, 3 and 6 months the alveolar ridge dimension changes were evaluated using an acrylic resin stent. At 3, 6 and 9 months one tissue sample was harvested in three selected patients and processed for histological analysis. At 9 months the authors also decided for implant placement with or without previous sinus floor augmentation.
Study B. This is a randomized double-blind controlled split-mouth clinical trial. Twelve patients requiring extraction of 2 controlateral maxillary premolar teeth were included. Following extractions in each patient, one randomly selected site was augmented with graft material (Bio-Oss Collagen, Geistlich) (control group), the other site was augmented and covered with collagen membrane (Bio-Gide, Geistlich) (test group). Following 5 weeks (early endopint, n=7 patients) or 12 weeks (late endpoint, n=5 patients) samples of newly-formed soft tissue were harvested and processed for evaluation of micro vascular density (MVD) (immunohistochemistry with CD31), collagen content (AA%) and amount of inflammatory infiltrate (immunohistochemistry with CD3 for T-lymphocytes and CD20 for B-lymphocytes). Non-parametric statistical analyses were performed to compare data from test and control groups at early and late endpoint. Data from the same group were also compared between early and late endpoints. Pearson’s correlation was used to compare intra-patient data.
RESULTS:
Study A. Data on alveolar ridge volume changes did not show significant differences between test and control group. However in the control group sites that maintained the buccal bone showed a substantial loss of buccal bone compared to the test group. At 3 months histological evaluation grafting material was detected immersed in highly cellular connective tissue. At 6 and 9 months grafting material was mainly remodeled and remaining particles were in contact with newly formed lamellar bone. The odds ratio for receiving the sinus augmentation before implant placement resulted 2.25 times greater in control group than in test group (p=0.39).
Study B. At 5 weeks after extraction, in both groups, epithelial and connective tissues appeared normally organized, without increased inflammatory infiltrate or cellular morphological alterations. Connective tissue of both groups presented remaining graft particles surrounded by mature
Tipologia IRIS:
Tesi di dottorato
Keywords:
alveolar socket ; histology ; immunohistochemistry ; augmentation ; soft tissue ; collagen membrane ; wound healing ; vascularization ; collagen
Elenco autori:
G. Pellegrini
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