Effect of rotary or manual instrumentation, with or without a calcium hydroxide/1% chlorhexidine intracanal dressing, on the healing of experimentally induced chronic periapical lesions

Objective. To evaluate the healing of experimentally induced chronic periapical lesions in dogs at 30, 75, and 120 days after root canal instrumentation with rotary NiTi files or manual K-files, with or without a calcium hydroxide/1% chlorhexidine paste intracanal dressing.Study design. The second, third, and fourth mandibular premolars and the second and third maxillary premolars of 5 dogs (12 to 18 months of age, weighing 8 to 15 kg) were selected for treatment (a total of 82 root canals). After pulp removal, the root canals were left exposed to the oral cavity for 7 days to allow microbial contamination, after which the root canals were sealed with ZOE cement until periapical lesions were confirmed with radiography. Group I and II teeth were instrumented with manual K-files using the crown-down technique. In group III and IV teeth, NiTi rotary files were used. The apical delta was perforated by using #20 to #30 K-files at the length of the tooth, thus creating a standardized apical opening. The apical stop was enlarged to size 70, with 2.5% sodium hypochlorite irrigation at each file change. Teeth in groups II and IV were dressed with calcium hydroxide (Ca(OH)(2))/1% chlorhexidine (CHX) paste for 15 days before root filling. Group I and III teeth did not receive an intracanal dressing. The access openings of the teeth were permanently restored with silver amalgam condensed on a glass ionomer cement base. Pairs of standardized periapical radiographs were taken at the beginning of the treatment (0 days) and at 30, 75, and 120 days after filling.Results. There was no significant difference in the rate of radiographic healing of the periapical lesions between manual and rotary instrumentation. Radiographs taken at 120 days showed that the treatment with Ca(OH)(2)/1% CHX paste resulted in a significant reduction in mean size of the periapical lesions in comparison to single-session treatment. These findings were also true for histologic observations.Conclusion. The findings support the hypothesis that, regardless of the instrumentation technique (manual or rotary), the use of an intracanal dressing is important in the endodontic treatment of dog's teeth with experimentally induced chronic periapical lesions.

Longitudinal clinical evaluation of adjunct minocycline in the treatment of chronic periodontitis

Background: the clinical benefits of minocycline in combination with thorough scaling and root planing (SRP) have been examined in multicenter studies. The aim of this longitudinal investigation was to evaluate the clinical response to scaling and root planing combined with the use of locally delivered minocycline microspheres for 720 days in individuals with advanced chronic periodontitis.Methods: A total of 26 individuals aged 26 to 69 years (mean: 46.8 +/- 12.1 years) were included in this double-blind randomized clinical trial. After randomization, 13 individuals were selected for the test group (TG) and treated with SRP plus subgingival minocycline at baseline and 90, 180, and 270 days, and 13 individuals were selected for the control group (CG) and received SRP plus vehicle at the same time-points. Two homologous sites with probing depth (PD) >= 6 mm were chosen in each subject. To evaluate the clinical response after treatment, PD, plaque index (PI), and gingival index (GI) were assessed at baseline and 90, 180, 270, 360, and 720 days.Results: No statistical differences were found between test and control groups in relation to PD at the different timepoints. The mean values of PD demonstrated a higher reduction in the test group at 270 and 360 days. No statistical differences were observed at 90, 180, and 720 days between TG and CG (P < 0.05; Wilcoxon test). There were no statistically significant differences between TG and CG concerning PI and GI (P < 0.05; analysis of variance and t test) at all evaluated timepoints.Conclusion: Our findings demonstrated that both therapies reduced mean PD from 90 to 360 days; however, SRP combined with the use of subgingival minocycline showed a higher reduction at 270 and 360 days following therapy.

A comparison of one versus two appointment endodontic therapy in dogs' teeth with apical periodontitis

This study was conducted to observe the healing process in dogs' teeth with apical periodontitis after root canal treatment in one or two appointments. Premolars and anterior dogs' teeth had their root canals opened to the oral environment for 6 months before being treated. After root canal negotiation they were filled by the lateral condensation technique with gutta-percha points and Sealapex in one appointment or after a dressing with calcium hydroxide for 7 and 15 days. Six months after the treatment the animals were killed and the tissues prepared for histomorphological analysis. Scores attributed to the different histomorphological events were submitted to statistical analysis, which resulted in ranking the experimental groups from the best to the worst in the following way: (a) calcium hydroxide 14 days; (b) calcium hydroxide 7 days; and (c) one appointment. It was concluded that the use of a calcium hydroxide dressing helps to achieve better results (p < 0.01) than the treatment in one appointment.

Effect of irrigating solution and calcium hydroxide root canal dressing on the repair of apical and periapical tissues of teeth with periapical lesion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of photodynamic therapy on the development of ligature-induced periodontitis in rats

Background: the purpose of this study was to evaluate, histologically and radiographically, the effect of photodynamic therapy on the progression of experimentally induced periodontal disease in rats.Methods: Ligatures were placed at the first mandibular molar in rats. The animals were divided into four groups: group 1 (C) received no treatment; group 2 was treated topically with methylene blue (MB; 100 mu g/ml); group 3 was treated with low-level laser therapy (LLLT); and group 4 was treated topically with methylene blue followed by LLLT (4.5 J/cm(2)) (photodynamic therapy; PDT). Rats were sacrificed 5, 15, or 30 days postoperatively. Standardized radiographs were taken to measure bone loss around the mesial root surface of the first molar. Data were analyzed statistically (analysis of variance and Tukey test; P < 0.05). A scoring system was used to evaluate the connective tissue, periodontal ligament, and alveolar bone histologically. Data were analyzed statistically (Kruskal-Wallis test; P < 0.05).Results: Radiographic examination showed that there was significantly less bone loss in Group PDT compared to Group C at 5 and 15 days postoperatively. There was no significant difference in bone loss at 30 days. At 15 days, the histologic results showed significant differences in the extent of inflammatory reaction in the gingival tissue, with a greater extent of chronic inflammatory reaction in Group LLLT.Conclusion: PDT transiently reduced the periodontal tissue destruction.

Evaluation of periapical repair following retrograde filling with different root-end filling materials in dog teeth with periapical lesions

Objective. The objective of this study was to evaluate periapical repair following retrograde filling using different root-end filling materials.Study design. After induction of periapical lesions, 48 root canals from do teeth were partially filled. Endodontic surgery was performed and 3 different materials were used for root-end filling: Sealer 26, Sealapex plus zinc oxide, or mineral trioxide aggregate (NITA). No additional procedures were performed in the control group after partial filling of the root canal. After 180 days, the animals were killed, the rnaxillas and mandibles were removed, and specimens were submitted for histologic processing.Results. Histopathologic analysis revealed similar periapical repair for the groups in which Sealer 26, Sealapex plus zinc oxide, and MTA were used (P >.05). The control group showed unsatisfactory periapical repair W <.05).Conclusion. There was no difference in periapical tissue healing alter retrograde filling with the tested materials, which indicates that these 3 root-end filling materials are equally useful.

Influence of Orthodontic Dental Movement on the Healing Process of Teeth With Periapical Lesions

The purpose of this study was to histomorphologically evaluate (in dog's teeth) the influence of tooth movement in the healing of chronic periapical lesions. Thirty roots of incisors and premolars of two dogs (1-year-old) were used in this research. After pulpectomy, the root canals remained exposed to the oral environment for 6 months for achievement of periapical lesions. Twenty root canals were biomechanically prepared and received a calcium hydroxide dressing for 14 days before being filled with gutta-percha points and Sealapex sealer. After root canal treatment, some incisors were submitted to orthodontic movement, whereas the other roots remained without orthodontic movement. The orthodontic appliance was removed at 5 months and 15 days after treatment, the dogs were killed 15 days later and the specimens were prepared for histomorphological analysis. The results showed that the orthodontic movement delayed, but did not hinder, the periapical healing process. (J Endod 2006;32:115-119)

Effect of a calcium hydroxide-based root canal dressing on periapical repair in dogs: a histological study

Objective. To compare the periapical repair of teeth with periapical lesion following root canal treatment by using a calcium hydroxide-based intracanal dressing for several time periods or filling in a single visit.Study design. After induction of periapical lesions in 4 dogs, the root canals were prepared using 5.25% sodium hypochlorite for irrigation, and animals were separated into 4 experimental groups; in group I, root canals were filled in a single session; in groups II, III, and IV, a calcium hydroxide-based dressing was kept in place for 15, 30, or 180 days, respectively. Root canals from groups I, II, and III were filled with gutta-percha cones and AH Plus sealer. After 180 days, animals were killed and histological sections were stained with hematoxylin-eosin to evaluate periapical repair.Results. Periapical repair was better in groups II, III, and IV (intracanal dressing) compared with group I (single session; P <.05).Conclusion. The use of a calcium hydroxide-based intracanal dressing was important for periapical repair in teeth with periapical lesion. Dressing with calcium hydroxide paste results in better periapical repair than when the root canal is filled in a single-session treatment.

Actinobacillus actinomycetemcomitans lipopolysaccharide-mediated experimental bone loss model for aggressive periodontitis

Background: Bacterial constituents, such as Gram-negative derived lipopolysaccharide (LPS), can initiate inflammatory bone loss through induction of host-derived inflammatory cytokines. The aim of this study was to establish a model of aggressive inflammatory alveolar bone loss in rats using LPS derived from the periodontal pathogen Actinobacillus actinomycetemcomitans.Methods: Eighteen female Sprague-Dawley rats were divided into LPS test (N = 12) and saline control (N = 6) groups. All artimals received injections to the palatal molar gingiva three times per week for 8 weeks. At 8 weeks, linear and volumetric alveolar bone loss was measured by micro-computed tomography (mu CT). The prevalence of inflammatory infiltrate, proinflammatory cytokines, and osteoclasts was assessed from hematoxylin and eosin, immunohistochemical, or tartrate-resistant acid phosphatase (TRAP)-stained sections. Statistical analysis was performed.Results: A. actinomycetemcomitans LPS induced severe bone loss over 8 weeks, whereas control groups were unchanged. Linear and volumetric analysis of maxillae by mu CT indicated significant loss of bone with LPS, administration. Histologic examination revealed increased inflammatory infiltrate, significantly increased immunostaining for interleukin IL-6 and -1 beta and tumor necrosis factor-alpha, and more TRAP-positive osteoclasts in the LPS group compared to controls.Conclusion: Oral injections of LPS derived from the periodontal pathogen A. actinomycetemcomitans can induce severe alveolar bone loss and proinflammatory cytokine production in rats by 8 weeks.