Treatment of endodontic perforations by guided tissue regeneration.

Case reports of mandibular molars with iatrogenic perforations are presented. Such perforations have been treated with internal amalgam repair or by surgical intervention. However, the potential exists for tissue migration and pocket formation. The use of guided tissue regeneration as a barrier for apical migration is beneficial in surgical treatment of perforations. Follow-up examination of perforated teeth treated with resorbable barriers showed successful repair. Results obtained with this technique offer the possibility of a successful repair for an otherwise hopeless complication of endodontic therapy.

Detection of interleukin-6 in human dental pulp and periapical lesions.

Pulpal and periapical diseases are characterized by inflammation. The cytokine IL-6 is a major mediator of the host response to tissue injury and infection. This study examined the level of interleukin-6 (IL-6) in six inflamed human pulps and six human periapical lesions of endodontic origin using ELISA. Pulp samples from eight clinically impacted teeth were used as controls. The periapical samples exhibited significant levels of IL-6 (mean = 78.1 +/- 9 pg/mg protein) as did inflamed pulpal tissues mean = 36 +/- 3.9 pg/mg protein) compared to healthy pulp mean = 0.01 +/- 0.02 pg/mg protein). These data indicated that IL-6 was produced and released locally in the inflamed pulpal and periapical lesions.

Fracture resistance of endodontically treated teeth restored with bonded amalgam and full crowns.

The use of dentin bonding prior to placement of core build-up restorations has been shown to reduce microleakage and reinforce remaining tooth structure. However, information is lacking about the influence a core build-up has on the fracture resistance of crowned teeth. The purpose of this in-vitro study was to compare the influence of three types of core build-ups on the fracture resistance of crowned teeth.

Effect of doxycycline on the apical seal of retrograde filling materials.

In this study, we examined the effect of doxycycline hydrochloride (DH) on the apical seal. Results indicated that teeth that were retrofilled with IRM or amalgam following doxycycline irrigation had significantly less dye penetration (p < 0.05). Due to its antimicrobial activity, smear layer removal ability, and improvement of apical seal, doxycycline solution may be used as an irrigant.

Removal of intracanal smear by doxycycline in vitro.

UNLABELLED: Cleansing and shaping result in a smear layer on the instrumented canal wall surfaces. The smear layer may inhibit close contact between sealers and dentin, and inhibits diffusion of medicaments. OBJECTIVE: This study assessed the effect of doxycycline hydrochloride (DH) on smear layer on intracanal walls. STUDY DESIGN: Scanning electron microscopy was used to evaluate the remaining smear layer using different concentrations of DH. Single-canal palatal roots of extracted maxillary molars were irrigated with saline-15% EDTA; saline-25 mg/ml DH; saline-50 mg/ml DH; saline-100 mg/ml DH; NaOCl-15% EDTA; NaOCl-25 mg/ml DH; NaOCl-50 mg/ml DH; and NaOCl-100 mg/ml DH. The roots were fractured into halves and the amount of smear layer assessed in the middle and apical third. RESULTS: Doxycycline-HCl of 100 mg/ml was the most effective in removing smear layer. In the saline group, 100 mg/ml of DH was more effective than EDTA. In the hypochlorite group, 50 mg/ml and 100 mg/ml of DH were more effective than EDTA (p < 0.05). CONCLUSION: Doxycycline solution may be an effective irrigant.

The effect of endodontic medicaments on the sealing ability of provisional restorative materials.

The purpose of this study was to determine the effect of intracanal medicaments on the sealing ability of commonly used provisional filling materials. Ninety extracted, unrestored human molars were prepared. The contents of the pulp chamber were removed, and distal and mesial root canal systems were cleansed to a size 25 file. Group A received a cotton pellet with no medication, group B a cotton pellet with Cresatin, and group C a cotton pellet with 2% iodine potassium iodide (IKI). The prepared teeth from each category were divided into three subgroups of 10 to receive Cavit, IRM, or TERM. After the fillings were placed, the teeth were thermocycled, stained, and sectioned longitudinally. The average dye penetration was greater in the medicated groups (B and C) than in the control group (A) for each provisional material tested. Statistical analysis revealed that sealing ability of all three filling materials was significantly affected by Cresatin and 2% IKI.

Effect of nonvital tooth bleaching on microleakage of resin composite restorations.

Thirty-six extracted, noncarious, nonfractured human incisors were divided into four groups of nine teeth. Endodontic access cavities were prepared, the pulp chamber was debrided, the root canals were cleansed, and root canal treatment was completed. Pulp cavities of teeth in group 1 received a cotton pellet and were sealed with Cavit. Groups 2, 3, and 4 received a mixture of 30% hydrogen peroxide and sodium perborate for 3, 4, and 7 days, respectively, were sealed with Cavit, and were stored in a humidor until used. Cavit and the other materials were removed, and the cavities were rinsed and restored with Scotchbond Multipurpose and Silux. The teeth were thermocycled, stained with 50% silver nitrate, and sectioned longitudinally. Dye penetration was measured. Results indicated that bleaching adversely affected the marginal seal at the tooth-restoration interface, as evidenced by increased microleakage; the highest rate of microleakage was found after the 7-day application of bleaching materials.

Microleakage of endodontic access cavities restored with composites.

A proper seal of restorative composites in endodontic access cavities is mandatory to prevent ingress of microorganisms and debris into the tooth-restoration interface. Chemically cured composites tend to have less polymerization shrinkage than photopolymerization composites. This study compared in vitro sealing performance of a chemically cured and a photopolymerization composite for access cavity restorations in endodontically treated teeth. In addition, the effects of four dentin pretreatments on the seal were evaluated. One hundred twenty-eight roots of extracted human incisors were cleansed, shaped and obturated with gutta percha and Grossman's sealer. The endodontic access cavities were later treated by Scotchbond Multipurpose, All-Bond 2, Vitrebond and Ketac-Bond. Half the access cavities within each group were filled by Coltene Microhybrid H.P., a chemically cured microhybrid composite. The other half were filled with Aelitfil, a photopolymerized composite. The filled teeth were thermocycled, submerged in silver nitrate solution, sectioned longitudinally, and their dye penetration measured and statistically analyzed by two-way ANOVA at 95 percent confidence level. The results show that the chemically cured composite allowed less dye penetration than the photopolymerized composite. As for the dentin pretreatments, the Scotchbond Multipurpose and All-Bond 2 exhibited less microleakage than Vitrebond and Ketac-Bond for both chemical and photopolymerized composite. Ketac-Bond allowed the highest amount of dye penetration, followed by Vitrebond, Scotchbond Multipurpose, then All-Bond, which had the least depth of microleakage. Chemically cured composites bonded with All-Bond 2 and Scotchbond Multipurpose may exhibit less microleakage than photopolymerized composites in endodontic access cavity restoration.

Cervical lymph node metastasis: model for study of head/neck melanoma.

Tumour cells spread from primary tumours to form distant metastatic deposits by both lymphatic and blood routes. Melanomas occurring in the head and neck have an extremely poor prognosis largely in part due to late detection resulting in extensive dissemination by lymphatic metastasis. The purpose of this study was to develop an animal model for the study of head and neck melanoma metastasis. B16-F1 parental cells were injected into the subcutis of the ear mid-lobule of C57BL/6 mice. At selected time periods after inoculation, animals were killed by cervical dislocation and autopsied. In some animals tumours had spread to the cervical lymph nodes. Examination of organ systems revealed no evidence of distant metastases. Histological examination of the cervical lymph nodes revealed tumour invasion, beginning at a subcapsular sinus and progressing into the paracortical sinuses. Cells from these nodes were adapted to cell culture, expanded by passage and reinjected into new mice. Subsequent generations of lymph node-selected B16 cell lines were more metastatic than their parental cell line, as evidenced by a more rapid appearance of cervical lymph node and extensive node invasion. Morphologically, the lymph node-selected B16 cell lines were more dendritic than the original B16-F1 parent line and had a larger number of pseudopodial projections. Perhaps increased expression of pseudopods by the metastatic variants may allow for greater migratory potential and hence increased metastatic ability. These results indicate that highly mobile variant B16 sublines can be selected with an increased capacity for cervical lymphatic metastasis.

Evaluation of the apical sealing ability of apatite root canal sealer.

The apical sealing ability of a tricalcium phosphate sealer was compared with that of three other sealers. Seventy roots of human incisors were cleansed and shaped and randomly assigned to one of seven groups of ten roots each. The root canal systems were obturated with gutta-percha and one sealer using the lateral-vertical condensation technique. The canal was sealed with Roth's sealer, Sealapex, Kerr root canal sealer, or Sankin apatite root sealer (Type I, II, or III). One group was filled with gutta-percha without sealer to serve as a control. After the roots were immersed in silver nitrate, the degree of dye penetration was measured under a dissecting microscope. Results indicated that Sealapex had the best sealing ability, followed by Sankin apatite root sealer, Type II. Roth's cement showed the most dye penetration. Canals that were obturated without sealer showed significantly greater apical leakage.

Detection of interleukin-1 beta in human periapical lesions.

Interleukins are involved in modulating bone cell activity. Interleukin-1 (IL-1) has been shown to be potent stimuli of bone resorption in organ culture. This hormone-peptide is produced primarily by monocytes and macrophages. Diverse inflammatory cell types are clearly present in periapical lesions. The purpose of this study was to detect IL-1 beta activity in human periapical lesions. Eight human periapical lesions were examined for the presence of IL-1 beta. Pulp tissue of clinically impacted teeth were used as controls. Each specimen was quick-frozen and stored in liquid nitrogen. IL-1 beta activity was measured with, an IL-1 beta enzyme-linked immunosorbent assay that used monoclonal antibodies specific for IL-1 beta. Periapical samples exhibited significant activity of IL-1 beta (mean 604.4 +/- 563.0 pg/mg protein), whereas normal pulp had no activity. These results demonstrate that IL-1 beta is produced and released locally in inflammatory periapical lesions to mediate bone resorption.

Treatment of vertical root fracture: a case report.

Vertical root fracture presents a diagnostic problem, and treatment is not usually successful. This case report demonstrates use of calcium hydroxide paste to induce healing of fractured roots. Glass-ionomer cement was used as a root canal sealer and then condensed into the root canals to bind the segments together.

The potential of periodontal pocket formation associated with untreated accessory root canals.

Teeth that were to be extracted because of periodontic-endodontic involvement, in six patients, were treated by hemisection or root amputation. The roots were processed histologically. All cases showed the presence of accessory root canals with remnants of pulpal tissue, bacteria, and necrotic debris. It was demonstrated in the cases studied that residual necrotic tissue in untreated root canals can result in periradicular pathosis. We may speculate that if the inflammatory process persists and drainage results via the sulcus, in time, plaque and then concretions may develop.

Evaluation of temperature rise on the outer surface of teeth during root canal obturation techniques.

The heat generated at the apical 2 mm of the outer root surface of extracted human canine teeth during three obturation procedures was measured. The rise in temperature was found to be less when a sealer was used in all obturation techniques. Temperatures as high as 44.02 degrees C were recorded with warm gutta-percha with no sealer, and the lowest temperature rise occurred with a thermoplasticized gutta-percha technique with a sealer. The thickness of the remaining dentin and cementum after cleaning and shaping were found to have no effect in reducing temperature rise. The results of this investigation indicated that temperature rise on the outer surface of the root as a result of heat-generating obturation procedures is negligible and will not have an effect on the supporting attachment apparatus.

Sealing ability of intermediate restorations and cavity design used in endodontics.

Temporary filling materials are used in endodontics to prevent contamination of the root canal system during intertreatment visits. Recently, a new composition resin (TERM) has been introduced as an interim restoration in endodontics. The purpose of this investigation was to evaluate the efficacy of this resin as an interim restoration and possible effect of access cavity design with respect to its sealing ability compared with other temporary restorative materials. Sixty human teeth were divided into two categories, and two types of access cavities were prepared, namely tapered access with walls divergent toward the occlusal surface and straight access with parallel walls. The prepared teeth from each category were divided into three subgroups of ten each to receive Cavit (group I), IRM (group II), or TERM (group III). After the fillings were placed, the teeth were transferred into a humidor where they stayed for 24 hours. The teeth were then thermocycled. Each group was thermocycled for 2 hours at 1 minute intervals at 60 degrees C and 4 degrees C. Then the teeth were sealed with a compound and coated with two layers of clear varnish, with the exception of cavity margins. Each occlusal surface was immersed in a vial containing silver nitrate. The teeth were sectioned longitudinally, and the degree of dye penetration was evaluated under a dissection microscope according to set criteria. Our findings demonstrated that design of cavity preparation was not a functional parameter in leakage pattern. Results indicated that Cavit had the best sealing ability whereas IRM showed the maximum dye penetration.

Evaluation of antimicrobial activity in vitro of ten root canal sealers on Streptococcus sanguis and Streptococcus mutans.

The antimicrobial activity of ten root canal sealers was studied on Streptococcus sanguis and Streptococcus mutans. One hundred plates of trypticase soy agar-sheep red blood cell (10%), each with four distinct 3 mm diameter wells, were divided into two groups of 50 by means of the Lawn technique; one group was inoculated with S. sanguis and the other with S. mutans. Four milligrams of each root canal sealer was placed in each of three wells in 10 plates (five plates of each inoculant); the fourth well was left empty as a control site. Plates were incubated at 37 degrees C and checked after 2, 7, and 14 days. All root canal sealers inhibited growth of both organisms. The inhibitory zones for S. sanguis were larger than inhibitory zones for S. mutans for all tested sealers, except Diaket. Dentinol, Kerr, and Tubliseal had significantly more inhibitory effect on S. sanguis than did other tested sealers (p less than 0.05). Diaket had superior inhibition on S. mutans.

Technical note: antimicrobial action of glass-ionomer lining cement on S. sanguis and S. mutans.

There are a number of glass-ionomer lining cements available to the profession. It is generally agreed that the glass-ionomer cements demonstrate reasonably good biocompatibility. The purpose of this study was to evaluate the antimicrobial activity of six glass-ionomer cements on S. sanguis and S. mutans. Forty-eight plates of TSA-SRBC (10%), each with 3.0-mm-diam. wells, were divided into two groups (1 and 2) of 24 each. Group 1 was inoculated with S. sanguis (10558) and Group 2 with S. mutans (6715-13 w.t.). Each well was filled with 4.0 mg of one of the following liners: Glassic (A), Shofu lining cement (B), GC lining cement (C), Ever Bond (D), Gingiva Seal (E), and Ketac Bond (F); the empty wells served as control. Plates were incubated under microaerophilic conditions at 37 degrees C, and checked daily over seven days for inhibition zones. Average inhibition zones (mm) at 7 days were as follows: Group 1-1A = 10.00, 1B = 7.83, 1C = 18.50, 1D = 13.00, 1E = 8.67, and 1F = 9.33; Group 2-2A = 3.08, 2B = 10.25, 2C = 12.75, 2D = 15.58, 2E = 8.83, and 2F = 3.20. All control wells were 0.0 GC liner and Ever Bond showed significantly greater overall inhibition of microbial growth than did other tested liners (p less than 0.5). A one-way ANOVA and SNK test showed that all tested liners were significantly more toxic toward S. sanguis than toward S. mutans (p less than 0.05).

An evaluation of sealing ability of calcium hydroxide sealers.

Solid core filling material such as gutta-percha has been used to fill the root canal in conjunction with a sealer to prevent apical leakage. The purpose of this study was to compare apical seal of five different root canal sealers. Sixty roots of maxillary central incisors were cleansed and shaped and randomly assigned to one of six groups of ten roots each. The root canals were obturated with gutta-percha and one of the sealers by the lateral-vertical condensation technique. Groups I, II, III, IV, and V consisted of roots in which the canal was filled with gutta-percha along with either Roth's sealer, AH26, Sealapex, CRCS, or Nogenol sealer, respectively. Group VI was filled with gutta-percha and without sealer to serve as a control. The access opening was filled with amalgam. Each tooth was then placed in a capped vial containing 2 X 2 inch gauze pads saturated with distilled water, and the sealer was allowed to set at 37 degrees C in the humidor for 48 hours. The roots, except for the apical 2 mm, were coated with two layers of nail polish. The roots were stained with india ink, decalcified, dehydrated, and then placed in methylsalicylate to make them transparent. The leakage was measured with a filar micrometer eyepiece under a dissecting microscope. The mean apical leakage of six groups was as follows: I = 0.45 mm, II = 0.277 mm, III = 0.343 mm, IV = 0.263 mm, V = 0.336 mm, and VI = 2.310 mm. Results showed no significant difference in the apical seal produced by gutta-percha and the tested root canal sealers.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of glass ionomers as retrofilling materials.

Many materials have been used as retrofillings. Because of the bonding property of glass ionomer cement, this study was conducted to evaluate its possible use as a retrofilling material. Seventy human maxillary anterior teeth were chosen. The root canal systems were cleansed and shaped, and the teeth were assigned to six groups of 10 each. The root canals were obturated with gutta-percha and Grossman sealer, and the apical 2 mm of each root was resected. In all groups a retrofilling preparation was made to a depth of a number 331 bur. The apical preparations were filled in the following manner: silver amalgam (group I), silver amalgam plus two layers of varnish (group II), Ketac-Silver plus two layers of varnish (group III), Ketac-Silver without varnish (group IV), Ketac-Fil plus two layers of varnish (group V), Ketac-Fil without varnish (group VI), and Ketac-Bond (group VII). All the root surfaces with the exception of 2 mm from the resected line were coated with two layers of clear varnish. All the teeth were immersed in methylene blue for 24 hours. After vertical sectioning, dye penetration was measured under a dissecting microscope. The mean apical leakage (in millimeters) was as follows: I = 0.57, II = 0.39, III = 0.22, IV = 0.54, V = 0.11, VI = 0.46, and VII = 0.17. One-way analysis of variance performed on the group means indicated that Ketac-Fil with varnish (group V) and Ketac-Bond (group VII) had significantly less leakage than other groups (p less than 0.05). This study indicates that Ketac-Fil and Ketac-Bond may have potential as retrofilling materials.