Survival of Composite Resin Restorations of severely Decayed Primary Anterior Teeth retained by Glass Fiber Posts or Reversed-orientated Metal Posts

Aim: The aim of this study was to compare the survival of composite resin restorations retained by glass fiber posts or reversed-orientated (upside-down) metal posts in severely decayed primary anterior teeth after 6, 12, and 18 months.

Materials and methods: A total of forty-four 3- to 5-year-old children with bilateral severely decayed primary maxillary canines were included. Patients were treated under general anesthesia. After pulpectomy, an intracanal post was seated in the primary maxillary canine on each side: either a glass fiber post or a metallic post in reversed orientation and teeth restored with light-cured composite. Survival rate of each technique was evaluated at predetermined follow-ups and data were analyzed with McNemar’s test (α = 0.05).

Results: The difference in survival of restorations retained by two types of posts was not statistically significant in clinical and radiographical evaluations after 6, 12, and 18 months. The survival rate of reversed-orientated metal and glass fiber posts after 18 months was 81.1 and 67.6% respectively (p = 0.14).

Conclusion: Reversed-orientated metal post did not show lower clinical survival compared with glass fiber posts in 18-month follow-up. Hence, reversed-orientated metal post can be considered as a potential method to obtain retention for composite restorations in severely decayed primary anterior teeth.

How to cite this article: Vafaei A, Ranjkesh B, L0vschall H, Erfanparast L, Jafarabadi MA, Oskouei SG, Isidor F. Survival of Composite Resin Restorations of severely Decayed Primary Anterior Teeth retained by Glass Fiber Posts or Reversed-orientated Metal Posts. Int J Clin Pediatr Dent 2016;9(2):109-113.

Age-related and site-specific changes in the pulpodentinal morphology of rat molars

The rat molars are frequently used as experimental models in endodontic research, but there is little systematic information available on the influence of age on the pulpodentinal organ in Wistar rat molars and it is often difficult to evaluate more subtle changes following experimental interventions. The aim here was to describe changes with age in first upper Wistar rat molars with specific reference to the pulpodentinal organ. Animals were perfused with glutaraldehyde at 19 days, 1, 3, 6, 8, 12, 16, or 24 months of age. First upper molars from 56 animals were demineralized in EDTA, embedded in Epon, and processed for light and transmission electron microscopy. Substantial variation in the structure of the dentine and odontoblasts was observed within the root canals and the coronal pulp chamber. In general, odontoblasts changed from a tall, columnar morphology in the coronal pulp chamber to a more cuboidal or flattened shape near the apex, particularly towards the interradicular space. Secondary dentine formation was more pronounced along the mesial aspect of the root chamber and corresponding to the bottom of fissures. Local tertiary dentine formation was layered in the upper pulp chamber, corresponding to occlusal attrition of the cusp. In several molars a local formation of irregular tertiary dentine was observed cervically in the mesial pulp chamber. After 1 year, a distinct protrusion of irregular dentine extended into the mesiocervical pulp, apparently corresponding to a denudation of cervical root dentine. Experimental pulp-capping studies frequently use first upper rat molars with perforations made through the mesial aspect of the crown; such perforations might be close to the irregular dentine in the mesiocervical region. In conclusion, this study identifies age-associated and regional changes of pulpodentinal morphology in first upper rat molars. Therefore, evaluation of morphological alterations following vital-pulp experiments should be done in specific age groups and at specific sites in the pulp.

Formaldehyde cytotoxicity in three human cell types assessed in three different assays

International standards for preclinical screening of the cytotoxicity of dental materials so far recommend the use of established cell lines. The aim of this study was to assess the relative susceptibility of human dental pulp fibroblasts (HPF), human buccal epithelial cells (HBE) and HeLa cervix cancer cells exposed to identical cytotoxic challenges. Formaldehyde, which may be released from dental materials such as dental composites, glassionomer cements, and endodontic sealers, was used as test chemical. Cytotoxicity data including dose-response relations and TC(50) values were assessed in three different assays: BrdU incorporation, neutral red uptake and MTT assays. HBE and HPF demonstrated statistically significant lower TC(50) values in both the neutral red and the BrdU assay in comparison to HeLa cells. In the MTT assay no statistically significant differences were observed between the cell types. In the two target-tissue cell types (HPF and HBE) the Neutral Red assay revealed lower TC(50) values in comparison to the BrdU assay. In HeLa cells no statistically significant differences were observed between the assays. In conclusion, the present study confirms that cytotoxicity data obtained by cell culture studies are influenced by both cell culture model and choice of assay. Under identical experimental conditions, human target tissue cells appeared to be more sensitive to formaldehyde toxicity than human HeLa cancer cells.

Pulp-capping with recombinant human insulin-like growth factor I (rhIGF-I) in rat molars

The aim of this study was to explore pulp healing and reparative dentinogenesis following pulp-capping by using recombinant human insulin-like growth factor I (rhIGF-I). Exposures were made through the mesial pulp horn in first upper molars in two-month-old Wistar rats. The pulp was covered with one dose of sterile 4% methylcellulose gel containing either 400 ng rhIGF-I or saline in contralateral controls. The exposure site was closed with sterile Teflon membrane, and the cavity was filled with IRM cement. Additional molars were capped with Dycal as controls. After 3, 7, or 28 days, animals were anesthetized and fixed by intravascular glutaraldehyde perfusion. Molars were decalcified and processed for histological analysis and cut with membrane and residual methacrylate from IRM in situ. Only specimens with acceptable pulp sealing according to blinded microscopy control were included. On day 3, identical inflammatory responses in the upper pulp were observed in molars with rhIGF-I gel or control gel. On day 7, granulation tissue ingrowth had partly replaced inflammatory infiltration in both groups. After 28 days, complete dentin bridging and tubular dentin formation were observed more frequently and closer to the test substance containing rhIGF-I. The reparative dentin response to capping with rhIGF-I was similar to that after the use of Dycal. In conclusion, microscopic control of membrane sealing in situ gives valid information on the more subtle pulp effects of growth factors. The observations suggest that pulp-capping of rat molars by means of rhIGF-I enhances reparative dentinogenesis in comparison with vehicle controls.