RESUMEN
AIM: To evaluate, using an experimental immature tooth model, the fracture resistance of bovine incisors submitted to different reinforcement treatments with mineral trioxide aggregate (MTA). METHODOLOGY: An immature tooth model was created by sectioning the coronal and apical portions of 40 bovine incisors 8 mm above and 12 mm below the cementoenamel junction. The root canals were irrigated with 1.0% sodium hypochlorite. They were enlarged both coronally and apically using number 703 carbide burs (ISO: 500-104-168-007-021) and their internal diameter was standardized to 2.1 mm. The specimens were assigned to four groups (n = 10): GI-control (without filling); GII-apical MTA plug + filling with gutta-percha and endodontic sealer; GIII-filling with MTA; GIV-apical MTA plug + filling with MTA + metallic post (Reforpost I). A polyether impression material was used to simulate the periodontal ligament. The specimens were submitted to a compressive load at a crosshead speed of 0.5 mm min(-1) in a servo-hydraulic universal testing machine (MTS 810) applied at 45 degrees to the long axis of the tooth until failure. Data were submitted to statistical analysis by the Kruskal-Wallis test at 5% significance level. RESULTS: GIV presented the highest fracture resistance (32.7N) and differed significantly from the other groups (P < 0.05). No statistically difference was found between GII (16.6N) and GIII (23.4N) (P > 0.05). GIII had a significantly higher fracture resistance than GI (P < 0.05). CONCLUSIONS: The use of MTA + metallic post as an intra-radicular reinforcement treatment increased the resistance to fracture of weakened bovine teeth in an experimental immature tooth model.
Asunto(s)
Compuestos de Aluminio/uso terapéutico , Compuestos de Calcio/uso terapéutico , Incisivo/química , Óxidos/uso terapéutico , Materiales de Obturación del Conducto Radicular/uso terapéutico , Silicatos/uso terapéutico , Fracturas de los Dientes , Animales , Bovinos , Fuerza Compresiva , Combinación de Medicamentos , Incisivo/lesiones , Modelos Teóricos , Resistencia a la TracciónRESUMEN
The purpose of this study was to investigate long-term pH changes in cavities prepared in root surface dentin of extracted teeth after obturation of the root canal with gutta-percha and a variety of sealers containing calcium hydroxide. After cleaning and shaping, root canals in 50 recently extracted, human single-rooted teeth were divided into five groups. Each of four groups was obturated with gutta-percha and either Sealapex, Sealer 26, Apexit, or CRCS, all of which contain calcium hydroxide. The remaining group served as the control and was not obturated with gutta-percha or sealer. Cavities were prepared in the facial surface of the roots in the cervical and middle regions. The pH was measured in these dentinal cavities at the initiation of the experiment, and 3, 7, 14, 21, 28, 45, 60, 90, and 120 days after obturation. Results indicate that the pH at the surface of the root does not become alkaline when calcium hydroxide cements are used as root canal sealers. Regardless of the sealer used, the observed pattern of pH change was not different from that seen in the control group of roots that were not treated with sealer. It is concluded that calcium hydroxide-containing cements, although suitable for use as root canal sealants, do not produce an alkaline pH at the root surface. If such a pH change is related to treatment of root resorption, these sealants do not contribute to this treatment.
Asunto(s)
Hidróxido de Calcio/farmacocinética , Dentina/metabolismo , Materiales de Obturación del Conducto Radicular/farmacocinética , Raíz del Diente/metabolismo , Bismuto/química , Bismuto/farmacocinética , Hidróxido de Calcio/química , Dentina/efectos de los fármacos , Permeabilidad de la Dentina , Difusión , Humanos , Concentración de Iones de Hidrógeno/efectos de los fármacos , Radical Hidroxilo/metabolismo , Materiales de Obturación del Conducto Radicular/química , Resorción Radicular/prevención & control , Salicilatos/química , Salicilatos/farmacocinética , Propiedades de Superficie , Cuello del Diente/efectos de los fármacos , Cuello del Diente/metabolismo , Raíz del Diente/efectos de los fármacos , Óxido de Zinc/química , Óxido de Zinc/farmacocinéticaRESUMEN
The purpose of this study was to determine the pH, after defined periods of time, in cavities prepared in the facial surface of the cervical, middle, and apical regions of roots obturated with calcium hydroxide pastes. Root canal instrumentation was performed on 40 recently extracted, single-rooted human teeth. Cavities 1.5 mm in diameter and 0.75 mm in depth were prepared in the cervical, middle, and apical regions of the facial surface of each root. Teeth were randomly divided into four groups. One group was left unobturated and served as a control. The three remaining groups were obturated with either aqueous calcium hydroxide, calcium hydroxide mixed with camphorated monochlorophenol. or Pulpdent pastes. Access cavities and apical foramina were closed with Cavit. Each tooth was stored individually in a vial containing unbuffered isotonic saline. pH at the surface was measured in the cervical, middle, and apical cavities at 0 and 3, 7, 14, 21, 28, 45, 60, 90, and 120 days. Results indicate that hydroxyl ions derived from calcium hydroxide pastes diffused through root dentin at all regions over the experimental period of 120 days. The pattern of pH change at the tooth surface was similar in all regions of the root, regardless of the type of calcium hydroxide paste used. This was a rapid rise in pH from a control value of pH 7.6, to greater than pH 9.5 by 3 days, followed by a small decline to pH 9.0 over the next 18 days, before finally rising and remaining at, or above pH 10.0 for the remainder of the experimental period. Pulpdent paste in the apical region was the only exception in this pattern, producing a pH rise nearly one full unit below the other pastes, pH 9.3. These results indicate that, for all pastes tested, a high pH is maintained at the root surface for at least 120 days.