Enamel matrix derivative versus guided tissue regeneration in the presence of nicotine: a histomorphometric study in dogs.

AIM: The goal of this histometric study was to compare the healing process of dehiscence-type defects treated by enamel matrix derivative (EMD) or guided tissue regeneration (GTR) under the effect of nicotine in the dog model. MATERIALS AND METHODS: Eight mongrel dogs were used. Buccal osseous dehiscences were surgically created on the mesial roots of the mandibular third and fourth pre-molars. The defects were exposed to plaque accumulation for 3 months. After this period, the defects were randomly assigned to one of the treatments: open flap debridement (OFD), EMD or GTR with a resorbable membrane. During 4 months, the dogs received subcutaneous administration of nicotine (2 mg/kg twice a day with a 12 h interval between the applications). After this period, the animals were killed and the blocks were processed. The histometric parameters evaluated included gingival recession, epithelial length, connective tissue adaptation, new cementum and new bone. RESULTS: A superior length of new cementum was observed in the sites treated by EMD in comparison with OFD (p< or =0.05). No statistically significant differences were observed between GTR and the other groups. CONCLUSIONS: In the presence of nicotine, EMD may promote more new cementum formation than OFD while GTR failed to provide a significant difference.

Smoking may affect the alveolar process dimensions and radiographic bone density in maxillary extraction sites: a prospective study in humans.

PURPOSE: Loss of ridge width and height typically occur after tooth extraction. This study aimed to investigate whether smoking would effect alveolar ridge remodeling after tooth extraction. MATERIALS AND METHODS: Twenty-one individuals (11 nonsmokers, 10 smokers) requiring a nonmolar extraction in the upper jaw were selected. Radiographs were taken 7 and 180 days after surgery, and the following parameters obtained: alveolar process height (AH), alveolar process width (AW), radiographic bone density in the postextraction socket (BDS), and in the pre-existing bone apically (BDPB). RESULTS: Six months after surgery, intragroup analysis showed that both groups presented a significant reduction in AH, while only smokers had a significant reduction in AW, BDS, and BDPB (P < .05). Furthermore, intergroup analysis showed that smokers presented lower BDS (91.45 pixels +/- 26.62 and 59.53 pixels +/- 19.99, for nonsmokers and smokers, respectively; P = .006) and continued to present lower BDPB (129.34 pixels +/- 42.10 and 89.29 pixels +/- 29.96, for nonsmokers and smokers, respectively; P = .023). Additionally, smokers presented a tendency for lower AH and AW than nonsmokers, but this was not statistically significant. CONCLUSION: Within the limits of the present study, smoking may lead to a more significant dimensional reduction of the residual alveolar ridge and postpone postextraction socket healing.

Coronally positioned flap with or without acellular dermal matrix graft in gingival recessions: a histometric study.

PURPOSE: To evaluate, histometrically, the healing of gingival recession treated by coronally positioned flaps (CPF) with or without acellular dermal matrix (ADM) as a subepithelial graft. METHODS: Gingival recessions were created on the upper cuspids of six dogs and were randomly assigned to: CPF+ADM (ADM group) or CPF alone (CPF group). After 4 months, the dogs were sacrificed, and the histometric measurements were performed. RESULTS: The epithelial length was 2.28 + 0.92 mm and 2.10 + 0.46 mm for the ADM and CPF groups, respectively (P=0.74). The connective tissue adaptation was 0.05 + 0.08 mm for the ADM group and 0.06 + 0.08 mm for the CPF group (P=0.36). The new cementum was 2.35 + 1.55 mm and 2.90 + 0.96 mm in the ADM and CPF groups, respectively (P=0.53). The new bone was 0.60 + 1.36 mm for the ADM group and 0.35 + 0.82 mm for the CPF group (P=0.53). The gingival recession was -0.88 + 1.33 mm in the ADM group and -0.21 + 0.22 mm in the CPF group (P=0.21). The gingival thickness was 1.63 + 0.28 mm in the ADM group and 1.16 + 0.20 mm in the CPF group (P=0.002).

Irrigação subgengival com clorexidina. Quais os benefícios? / Subgingival irrigation with chlorhexidine. Which are the benefits?

Diante da associação da placa bacteriana com o desenvolvimento da gengivite e progressão da periodontite, agentes químicos de controle de placa têm sido empregados na prevenção da doença periodontal e no seu tratamento. A clorexidina tem sido considerada o gold standard dos agentes antiplaca, porém seus efeitos colaterais limitam seu uso prolongado para prevenção. Sabendo-se da dificuldade dos antimicrobianos atingirem as porções mais profundas das bolsas periodontais através de meios conven¬cionais, como escovação e bochechos, grande interesse foi dado à aplicação de clorexidina diretamente no interior das bolsas periodontais. Logo, o objetivo deste trabalho é apresentar uma revista bibliográfica com os estudos que utilizaram a clorexidina para irrigação subgengival, como método coadjuvante da terapia mecânica convencional, avaliando seus possíveis benefícios.

Histologic evaluation of the effect of nicotine administration on bone regeneration: a study in dogs

O objetivo do presente estudo foi avaliar histometricamente a influência da nicotina sobre a regeneração óssea de defeitos criados cirurgicamente em rebordos alveolares edêntulos de cães. Defeitos ósseos foram criados cirurgicamente em um dos lados da mandíbula de dezesseis cães e foram deixados para que curassem espontanea-mente. Os animais foram aleatoriamente designados para um dos seguintes grupos: Grupo 1 - controle (n = 8) e Grupo 2 - administração subcutânea de nicotina (2 mg/kg) duas vezes ao dia durante 4 meses (n = 8). Os animais foram sacrificados, e secções semi-seriadas descalcificadas, obtidas. Os parâmetros histométricos avaliados foram altura, largura, área e densidade do tecido ósseo neoformado. A análise intergrupos (Mann-Whitney "rank sum test") demonstrou que a administração de nicotina não influenciou altura, largura e área de tecido ósseo neoformado (p > 0,05). Entretanto, a administração de nicotina influenciou significativamente a densidade do tecido ósseo neoformado (p < 0,001). Dentro dos limites do presente estudo, pode-se concluir que a nicotina pode afetar, mas não impedir a regeneração de defeitos ósseos criados cirurgicamente em mandíbulas edêntulas de cães.

Histologic evaluation of the effect of nicotine administration on bone regeneration. A study in dogs.

The objective of this study was to investigate the histometric impact of nicotine on bone regeneration of surgically created alveolar ridge defects in dogs. Sixteen mongrel dogs were used. One defect was surgically created unilaterally in the mandible, and left to heal spontaneously. The animals were randomly assigned to one of the following groups: Group 1--control (n = 8) and Group 2--subcutaneous nicotine administration (2 mg/kg) twice a day (n = 8). After 4 months, the animals were sacrificed and the specimens routinely processed for semi-serial decalcified sections. Bone height (BH), bone width (BW), bone density (BD), and bone area (BA) of the newly-formed bone were evaluated. Intergroup analysis (Mann-Whitney rank sum test) showed that regardless of the presence of nicotine, no significant differences were observed regarding bone width (BW), bone area (BA) and bone height (BH) (p > 0.05). On the other hand, it was demonstrated that nicotine administration significantly influenced the proportion of mineralized tissue within the limits of the newly-formed bone (BD) (p < 0.001). Within the limits of the present study, it can be concluded that nicotine might affect but not prevent bone healing in defects left to heal spontaneously.