AN ANATOMICAL STUDY OF THE LATEROTRIGEMINAL VENOUS SYSTEM

The middle cranial fossa of 100 cadavers were dissected under stereoscopic loupe in order to identify and systematize the venous vessels located along the lateral margin of the trigeminal cave. The author found that at the sensitive root and trigeminal ganglion level a dural venous canal was present in most individuals examined and that the upper side of this canal communicated with the superior petrosal sinus. However, at the level of the lateral border of the intracranial segment of the mandibular nerve, venous lacunae were found to prevail, and these lacunae communicated with several other venous formations in the peritrigeminal region. The author concludes that the venous vascularization of this area constitutes a major risk in surgical interventions made in the middle cranial fossa. In addition, it is a relevant factor in the hemodynamics of the intracranial circulation.

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.

Scanning electron microscopic study of the cleaning ability of chlorhexidine as a root-canal irrigant

Aim To evaluate in vitro the cleaning of root-canal walls after irrigation with different irrigants.Methodology A total of 36 recently extracted human teeth were divided into four experimental groups according to the irrigating solution used: saline; 2% chlorhexidine; 2.5% sodium hypochlorite; and 2.5% sodium hypochlorite + EDTA. The cleaning of the apical, middle and coronal thirds of the root canals was evaluated by scanning electron microscope examination using a 4-point scoring system.Results the best cleaning was obtained using 2.5% sodium hypochlorite and EDTA, followed by 2.5% sodium hypochlorite only (P < 0.05), whose cleaning was similar to chlorhexidine only in the cervical third. Cleaning by saline and 2% chlorhexidine was worse than the other two groups and was similar in all thirds. Better cleaning was found in the cervical and middle thirds for all groups with the worst results in the apical third.Conclusions the apical third of the root canals was not cleaned as well as the middle and coronal thirds. Cleaning by chlorhexidine and saline was inferior compared to the cleaning by sodium hypochlorite with and without EDTA.

Tissue response to an epoxy resin-based root canal sealer

The objective of the present study was to evaluate two different types of root canal sealers: AH Plus (an epoxy resin-based sealer) and Fill Canal (a zinc oxide-eugenol based sealer). A total of 34 root canals with vital pulp from dogs' premolars were used. After instrumentation, the root canals were filled with gutta-percha and AH Plus or gutta-percha and Fill Canal sealers using a classical technique of lateral condensation. After histological processing, the sections were stained with hematoxylineosin or Mallory's trichrome stain. Inflammatory cells or areas of necrosis were not associated with AH Plus. Hard tissue formation apically to the material was observed in 14 specimens. The Fill Canal sealer presented an inflammatory response of moderate intensity in the periapical region, mainly adjacent to the material.

Electromyographic study of the temporal, masseter and suprahyoid muscles in the mandibular rest position

The temporal muscles (anterior position), and the masseter and suprahyoid muscles were studied electromyographically in 15 subjects with ages ranging from 18 to 35 years, showing normal occlusion (Class I of angle), complete dentition and no dysfunction of the stomatognathic system. The volunteers sat comfortably in a chair, keeping the Frankfurt plane parallel to the boor; the muscles were analysed in the mandibular resting position through a number of stages: with minimum exteroceptive stimuli, relaxation with soft music, abolition of the intrabuccal negative pressure through a plastic tube, stress provoked by an electronic game, disocclusion of posterior teeth using the occlusal splint and finally withdrawal of this device. The electromyographic results were analysed statistically. The samples, were analysed for all of the frequencies of motor units, in a 1-min period. It was found that there were statistically significant difference between the relaxation stages as compared with the withdrawal of negative intraoral pressure and mainly with the stress phase, being this only on the suprahyoid muscles, with 5% significance.

Mandibular skeletal growth and modelling between 10 and 15 years of age

This study pertains to a random sample of untreated French-Canadian adolescents (79 females and 107 males) evaluated at 10 and again at 15 years of age. Superimpositions on natural reference structures were performed to describe condylar growth and modelling of 11 mandibular landmarks. Superimpositions on natural cranial/cranial base reference structures were performed to describe mandibular displacement and true rotation.The results showed significant superior and posterior growth/modelling of the condyle and ramus. Males underwent significantly (P < 0.01) greater condylar growth and ramus modelling than females. With the exception of point B, which showed significant superior drift, modelling changes for the corpus landmarks were small and variable. The mandible rotated forward 2-3.3 degrees and was displaced 9.6-12.7 mm inferiorly and 1.9-2.7 mm anteriorly. Individual differences in ramus growth and modelling, both amount and direction, can be explained by mandibular rotation and displacements. Multivariate assessments revealed that superior condylar growth and ramus modelling were most closely associated with forward rotation and inferior mandibular displacement. Posterior growth and modelling were most closely correlated with anterior mandibular displacement and forward rotation. Modelling of the lower anterior border was independent of rotation and displacement.

Influence of root canal dressings and sealers on repair of apical periodontitis after endodontic treatment

Objective. The objective of this study was to evaluate the histopathologic response of periapical tissues after root canal treatment of necrotic dog teeth with chronic apical periodontitis by using 2 calcium hydroxide-based root canal dressings and 2 root canal sealers.Study design. Seventy-eight root canals were instrumented by using 5.25% sodium hypochlorite as the irrigating solution, after which a calcium hydroxide paste (Calen/PMCC or Calasept) was placed for 30 days as a dressing. The root canals were then filled by using cold lateral gutta-percha condensation and an enclodontic sealer (Sealapex or AH Plus). After 360 days, the animals were killed by anesthetic overdose; then, the teeth were histologically prepared, sectioned, and stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical tissue repair.Results. Statistical analysis showed that the poorest histopathologic results were observed in the Calasept/AH Plus group and that the Sealapex sealer overall resulted in better apical repair than the AH Plus sealer. The histopathologic results of Calen/PMCC paste with both AH Plus and Sealapex and Calasept paste with only Sealapex were statistically similar but were different from the results of Calasept with AH Plus.Conclusions. The results of this study in the dog showed differences in apical and periapical tissue repair of teeth with chronic apical periodontitis by using 2 calcium hydroxide root canal dressings and 2 sealers. More research is necessary to determine the best combination of dressings and sealers.

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)

Prevalence of different types of accessory canals in the furcation area of third molars

Background: Although there are several studies that show the prevalence and diameter of accessory root canals in the furcation area, there is a scarceness of studies that observe the trajectory and different types of cavo-interradicular canals. The aim of this study was to verify the prevalence of the different morphologic types of accessory canals in the furcation region in an attempt to show their trajectories.Methods: Forty submerged mandibular third molars were used, which were extracted and decalcified so that the microtomy procedure in the mesio-distal axial plane could be performed, obtaining semiserial sections with thicknesses of 5 mu m. The sections were stained with hematoxylin and eosin and observed under optical microscopy.Results: All of the morphologic types were found, whereas the proper accessory canals, type-A canals, were present in 10% of the specimens. The most prevalent canals were the sealed ones (type D), with a prevalence of 87.5%, followed by the blind ones (type B), with a prevalence of 75%. The loop accessory canals (type C), observed in only 5% of the teeth, were the least prevalent ones.Conclusions: Different morphologic types of accessory canals were found in the furcation area of submerged mandibular molars. The histologic method was effective to show the canal trajectories.