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At least 73 records · Page 4Linked to original sources

PubMed2005

Shear bond strength evaluation of composite resin on enamel and dentin after nonvital bleaching.

BACKGROUND: Studies have shown that bleaching agents interfere with the adhesion of composite resin placed immediately after bleaching. PURPOSE: The aim of this study was to evaluate the shear bond strengths of composite resin after four different durations since the time of nonvital bleaching (1 d and 1, 2, and 3 wk). MATERIALS AND METHODS: Two hundred seventy bovine teeth were assigned to nine groups (n = 30) according to the bleach used and the time between bleaching and restoration: group 1--sodium perborate (SP), 1 day after bleaching (AB); group 2--SP, 1 week AB; group 3--SP, 2 weeks AB; group 4--SP, 3 weeks AB; group 5--37% carbamide peroxide (CP), 1 day AB; group 6--CP, 1 week AB; group 7--CP, 2 weeks AB; group 8--CP, 3 weeks AB; group 9--control group (no treatment). After the bleaching treatment, the teeth in each group were sectioned and the enamel and dentin were separated. The teeth were cut, embedded in polyester resin, and polished to obtain flat enamel and dentin surfaces. The adhesive system was applied and a cylinder of composite resin was bonded on each flat surface. The specimens were stored in distilled water for 7 days at 37 degrees C. The shear bond strength test was performed in a universal test machine (Emic DL-500, São José dos Pinhais, São Paulo, Brazil) at a crosshead speed of 0.5 mm/min. RESULTS: The data were subjected to analysis of variance, Dunnett's t-test, and Tukey's least significant difference at p < or = .05 and showed a statistically significant decrease in bond strengths of composite resin for enamel and dentin 1 day after the nonvital bleaching. CLINICAL SIGNIFICANCE: The decrease in shear bond strength values is time dependent. A delay in bonding procedures for composite resin restoration is recommended. According to the results, a satisfactory time to perform the restoration of composite resin for both enamel and dentin is 2 weeks after bleaching.

Analysis of Variance↗

PubMed2004

Treatment selection for anterior endodontically involved teeth.

Innovations in material science and clinical techniques have expanded the number of treatment options available for nonvital anterior teeth. These options include the use of composite to fill the access opening with no additional treatment, crown placement, orthodontic extrusion, crown lengthening with or without orthodontic extrusion, dowel restorations with crown placement, and fixed bridge or implant therapy when extraction is necessary. Clinicians need to understand the benefits and limitations of each option in order to provide their patients with optimum function and aesthetics. Using case presentations, this article describes predictable approaches for the diagnosis, treatment planning, and restoration or replacement of endodontically treated teeth in the anterior region.

Adult↗

PubMedDate not supplied

Pulpal blood flow in vital and nonvital young permanent teeth measured by transmitted-light photoplethysmography: a pilot study.

PURPOSE: The purpose of this study was to record transmitted-light photoplethysmography (TLP) from young permanent teeth and examine its applicability to pulp vitality assessment. METHODS: Twenty-six healthy and 7 nonvital upper maxillary incisors in 17 children (ages 7 years, 3 months to 14 years, 8 months) were examined. Recordings of TLP were made with and without opaque black rubber dam application in a darkened room. Finger photoplethysmography (FPP) of the participants was simultaneously recorded. RESULTS: (1) Pulse waves synchronous with FPP were recorded from all healthy teeth, whereas no pulse signals were recognized in nonvital teeth. (2) The signal amplitude in the TLP was not significantly affected by the opaque dam application. (3) In the healthy teeth, there was a significantly negative correlation between the TLP pulse amplitude and the age of the subjects. CONCLUSIONS: TLP can detect pulpal blood flow in young permanent teeth. This technique is considered to be applicable in the assessment of pulp vitality.

Adolescent↗

PubMed2004

The effect of nonvital bleaching on the shear bond strength of composite resin using three adhesive systems.

PURPOSE: To evaluate the effect of nonvital bleaching on the shear bond strength of composite resin using three adhesive systems. MATERIALS AND METHODS: Two hundred seventy bovine teeth were assigned to 3 groups (n = 90): SP, paste of sodium perborate and water; CP, 37% carbamide peroxide; CO, control group (no treatment). After the bleaching treatment, the teeth in each group were cut into enamel (E) and dentin (D) sections. The teeth were embedded in polyester resin and polished in order to obtain a flat E or D surface. Each group was divided into 6 subgroups (n = 15) according to substrate (E and D) and adhesive system: SB, Single Bond (solvent: water/alcohol); PB, Prime & Bond NT (solvent: acetone); CLF, Clearfil SE Bond (solvent: water). The adhesive system was applied on each flat surface according to the manufacturer's instructions and a cylinder of composite resin Z-250 was overlaid. The specimens were stored in distilled water for 7 days at 37 degrees C. The SBS test was performed in a universal testing machine with crosshead speed of 0.5 mm/min. The data obtained (in MPa) were statistically analyzed with two-way ANOVA and Tukey's test (p < or = 0.05). RESULTS: The bleaching treatment influenced the SBS, regardless of the adhesive system used. On enamel, the SP and CP bleaching treatments reduced the SBS values. On dentin, the SP bleaching agent reduced the SBS values, but the CP bleaching did not. CONCLUSION: Nonvital bleaching treatment with sodium perborate may adversely affect shear bond strength of composite resin for both enamel and dentin. Similar effects can be expected from 37% carbamide peroxide bleaching agent on enamel but not dentin bonding strength. The use of water/alcohol and acetone-based adhesive systems cannot reverse the effects of bleaching treatments on bond strengths.

Analysis of Variance↗

PubMed2004

Pulpal necrosis with sickle cell anaemia.

AIM: To investigate radiographic manifestations of sickle cell anaemia (SCA) and whether or not a pulpal necrosis may develop without a pathological history. METHODOLOGY: Thirty-six patients with homozygous SCA were evaluated, and a further 36 individuals without SCA were included in the study as a control group. All 72 patients participating in the study ranged between the ages of 16 and 40 years. General and dental histories of the individuals were recorded. Electrical pulp test, percussion and thermal tests were applied to all the teeth having no restorations. Orthopantomograms of all the subjects were taken. Data obtained from questionnaires, sensitivity tests and radiographic examinations were evaluated by chi-square and Fischer's exact test. RESULTS: Fifty-one (6%) of the teeth having no restorations or history of trauma were determined as being nonvital in the SCA group. In 30 (83%) of these patients orofacial and dental pain with no obvious cause was detected and in 24 (67%) of the patients the quality of the bone tissue as examined radiologically had deteriorated. In eight (22%) of the patients cortical thinning and irregularity in the mandible was noted. A statistically significant difference between the SCA and control groups (P < 0.05) was found in terms of pulpal sensitivity and radiological findings. CONCLUSION: SCA is a genetic and systemic disease which may cause pulp necrosis without necessarily having an identifiable aetiology. SCA causes radiographically observable differences in jaw structure especially in the mandible.

Adolescent↗

PubMed1998

Antimicrobial activity of 2.5% sodium hypochlorite and 0.2% chlorhexidine gluconate separately and combined, as endodontic irrigants.

Sodium hypochlorite irrigant is known to be toxic to periapical tissues. Chlorhexidine gluconate, a safer and effective antimicrobial irrigant, is not known to dissolve pulpal tissues. To obtain their optimal properties, their combined action within the root canal was evaluated. Ten single rooted nonvital anterior teeth were irrigated using either 2.5% sodium hypochlorite alone, 0.2% chlorhexidine gluconate alone, 2.5% sodium hypochlorite and 0.2% chlorhexidine gluconate combined within the root canal, or 0.9% saline, respectively. Microbiological samples for culture and Gram's staining were taken before and proceeding irrigation. This study indicates that the use of sodium hypochlorite and chlorhexidine gluconate combined within the root canal resulted in the greatest percentage reduction of postirrigant positive cultures. This may be due to formation of "chlorhexidine chloride," which increases the ionizing capacity of the chlorhexidine molecule. This reduction was significant compared to use of sodium hypochlorite alone but not significant compared to use of chlorhexidine gluconate alone.

Anti-Infective Agents, Local↗

PubMed1996

Intracoronal bleaching of nonvital teeth in children and adolescents: interim results.

This study was undertaken to investigate the outcomes in 20 children and adolescents who had undergone an intracoronal nonvital bleaching technique. Twenty-one discolored central incisor teeth were treated by the walking bleaching method and reviewed at intervals for 18 months following completion of bleaching. All teeth bleached lightened to varying degrees, and 62% of patients expressed satisfaction with the result. When a porcelain shade guide was used as a reference before bleaching, the percentage of teeth deemed off the shade guide, gray or reddish gray, was 97%. Immediately postbleaching, the percentage had been reduced to 57%, and relatively more teeth were at the lighter end of the scale for each color band. At 18 months, three teeth (17%) had been veneered, and 33% of the remainder were found to be off the shade guide, gray or red-gray. Radiographically, 81% of teeth were classified as healthy at 18 months, with no evidence of cervical or progressive apical resorption.

Adolescent↗

PubMed2006

Bleaching teeth treated endodontically: long-term evaluation of a case series.

The chromatic stability of nonvital discolored teeth, subjected to the combined intracoronal bleaching technique and to endodontic treatment, was evaluated at a distance of 16 yr (1989-2005). The series comprised 50 patients (age range 7-30 yr) selected from among those attending the Dental Clinic at "Federico II" University, Naples, between 1987 and 1989. After 16 yr, only 35 cases could be evaluated: in 22 of these cases (62.9%) the color had remained stable and was similar to that of adjacent teeth, indicating a successful outcome of the combined bleaching technique. There were 13 cases (37.1%) classified as failures because of marked color relapse. Radiology showed none of the cases re-examined to have undergone internal or external root resorption. These results confirm the validity of the combined intracoronal bleaching technique in terms of efficacy, rapid esthetic result, and safety.

Adolescent↗

PubMed2001

A study in two centres of variations in the time of apical barrier detection and barrier position in nonvital immature permanent incisors.

OBJECTIVES: To study barrier formation in nonvital, immature permanent incisors being treated using the apexification technique in two centres, and to establish the effect of the frequency of change of calcium hydroxide (CaOH) on barrier detection times. DESIGN: A retrospective study of the time of detection and the position of barriers. RESULTS: There were no significant differences between the two centres in terms of the average frequency of change of each CaOH dressing, the distribution of barrier detection times or the position of barriers (P > 0.05). There was a total of 107 teeth and the time of barrier detection was significantly earlier in more frequently dressed teeth (P = 0.013). Of the teeth with a barrier detection time of less than 9 months, 60.7% were dressed more frequently than every 3 months, as opposed to 39.1% of teeth with longer barrier times (P = 0.027). The mean time of barrier detection for all cases was 43.3 weeks. The majority of barriers were located at or near the apex. CONCLUSION: The frequency of change of CaOH can increase the speed of barrier detection but does not appear to affect the position.

Analysis of Variance↗

PubMed2001

Cytotoxicity of intracanal bleaching agents on periodontal ligament cells in vitro.

Intracoronal bleaching of nonvital teeth is a simple and conservative procedure for esthetic restoration of discolored teeth. However it is possible that damage to the periodontal ligament may occur if the bleaching agents contact this tissue. The purpose of this study was to examine the cytotoxicity of intracanal bleaching agents on human periodontal ligament (PDL) cells in vitro. Three bleaching agents, 30% hydrogen peroxide (H2O2), 2.0 g/ml sodium perborate (SP) solution, and 2.0 g/ml SP in H2O2, were diluted from 10(-3) to 10(-7) with Eagle's minimal essential medium and incubated with PDL cells isolated and cultured from extracted teeth. Cytotoxicity was assessed quantitatively by determining the amount of lactic dehydrogenase activity released from the cells after exposure to the agents for 24 or 72 h. Dose-response curves were plotted, and TD50 values (dilution causing the release of 50% of control lactate dehydrogenase activity) and 95% confidence limits determined. The rank order of the TD50 values after exposure for 24 h was SP in H2O2 (most toxic) > H2O2 > SP solution (least toxic). After 72 h SP in H2O2 still produced the greatest cytotoxic effect. However the SP solution was more cytotoxic than H2O2 at this time point. It is concluded that the mixture of SP with H2O2 was the most toxic to the PDL cells in vitro.

Borates↗

PubMed1997

A histological and quantitative histomorphometric study of apexification of nonvital permanent incisors of vervet monkeys after repeated root filling with a calcium hydroxide paste.

The purpose of this study was to compare the effect of a monthly refilling of the root canals with calcium hydroxide paste with a single packing or replacement of the paste at 3 months on the apexification of nonvital maxillary incisors of vervet monkeys. Forty-eight maxillary incisors from 12 monkeys were used following radiographic determination that root development was incomplete. The pulps were extirpated under general anesthesia and the root canals filed and cleaned. The root canals were filled with a commercial calcium hydroxide paste, Calxyl, and a temporary cavity filling placed. Twelve teeth were left without further treatment. The calcium hydroxide paste was replaced in 12 teeth after a 3-month interval, and in the remaining 24 teeth the calcium hydroxide root filling was replaced five times at monthly intervals. The monkeys were killed after 6 months, and blocks of the teeth and surrounding tissues were embedded, decalcified and 6 microns serial sections prepared and stained. The sections were studied histologically to evaluate 11 parameters. Significant differences were found in the amount of calcium hydroxide at the apices, the presence of new cementum on the roots and the degree of inflammation, all of which were better in the monthly refill group. Histomorphometric measurements to evaluate the obturation of the open apices and the volume of new primary osteocementum showed no significant difference between the three groups. It was suggested that after the initial root filling with calcium hydroxide there was nothing to be gained by repeated root filling either monthly or after 3 months, for at least 6 months.

Analysis of Variance↗

PubMed2002

Postoperative pain after 1- and 2-visit root canal therapy.

OBJECTIVES: The factors that influence postoperative pain after root canal treatment are not completely understood. The purpose of this prospective clinical study was to evaluate postoperative pain after root canal therapy performed in 1 appointment versus 2 appointments. STUDY DESIGN: Seventy-two patients requiring root canal therapy on permanent molars were included in this study. Patients were randomly assigned to either the 1-appointment or the 2-appointment group. Both vital and nonvital teeth were included. The standardized protocol for all teeth involved local anesthesia, isolation and access, engine-driven rotary nickel-titanium canal instrumentation to a minimum size #5 (.028 mm).04 taper Profile with step-back flaring, and irrigation with 2.5% NaOCl. Teeth in group 1 (n = 39) were obturated at the first appointment by using laterally condensed gutta-percha and Roth 811 sealer. Teeth in group 2 (n = 33) were closed with a sterile dry cotton pellet and Cavit restoration and were obturated at a second appointment 7 to 14 days later. A modified Visual Analogue Scale was used to measure preoperative pain and pain at 6, 12, 24, and 48 hours after the first appointment. Statistical analysis was performed to compare groups at each interval by using an independent-samples t test with Bonferroni adjustment. RESULTS: There was no statistically significant difference between groups at preoperative intervals or at any of the 4 postoperative intervals (P <.01). CONCLUSIONS: There was no difference in postoperative pain between patients treated in 1 appointment and patients treated in 2 appointments. The majority of patients in both groups reported no pain or only minimal pain within 24 to 48 hours of treatment.

Appointments and Schedules↗

PubMed2006

The effect of fiber insertion on fracture resistance of endodontically treated molars with MOD cavity and reattached fractured lingual cusps.

In this study, the effect of flowable composite reinforced with a leno wave ultra high modulus (LWUHM) polyethylene fiber (Ribbond) on fracture resistance of endodontically treated molars with MOD cavity and lingual cuspal fracture was evaluated. Sixty sound extracted human mandibular molars were randomly assigned to six groups (n = 10). Group 1 served as control. Teeth in groups 2-6 received root canal treatment and a MOD cavity preparation. Teeth in group 2 were kept unrestored. Lingual walls of specimens in groups 3-6 were fractured at the CEJ and reattached (C&B Super-Bond). Group 3 was kept unrestored, and group 4 was restored with a composite resin (CR) (AP-X). In group 5, a flowable resin (FR, Protect Liner F) and in group 6, a Ribbond in combination with FR were inserted inside the cavity before CR restoration. After finishing and polishing, the specimens were subjected to compressive loading perpendicular to the occlusal surface at a crosshead speed of 1 mm/min. The mean load necessary to fracture were recorded in Newton and the results were statistically analyzed. MOD cavity preparation reduced fracture resistance of endodontically treated teeth (p < 0.05). Fracture resistance of rebonded fractured specimens was found to be similar to that of the nonfractured samples (p > 0.05). Use of LWUHM polyethylene fiber Ribbond increased fracture strength of endodontically treated molar teeth with MOD cavity preparation and cuspal fracture (p < 0.05). As a result, it was concluded that the insertion of Ribbond inside the cavity has a positive effect on fracture strength of endodontically treated molar teeth with MOD cavity preparation and cuspal fracture.

Dental Materials↗

PubMed1998

The effect of glass ionomer cement or composite resin bases on restoration of cuspal stiffness of endodontically treated premolars in vitro.

The purpose of the present study was to decide whether composite resin or conventional glass ionomer cement should be preferred as a base material in endodontically treated premolars. Twelve extracted human maxillary premolars were mounted in a universal testing machine at a 35 degrees angle. Cuspal stiffness was determined by applying a load of 75 N to the buccal cusp and recording the displacement of the cusp using inductive displacement transducers. In the same teeth, different cavity preparations and restorations were performed sequentially. Standard MOD cavities were enlarged to allow endodontic access. In addition, the cusps were undermined. Half of the teeth were restored to the level of the previous shallow cavities using conventional glass ionomer cement (Ketac Fil), in the rest of the teeth dentine bonding agent (Syntac) and composite resin (Tetric) were used instead. Finally, composite resin fillings (Tetric) were placed. All restorations were removed and the experiments were repeated twice. For each replication, the assignment of the base materials to the experimental groups was reversed, and ceramic inlays (Empress) were used as final restorations for the last replication. Improvement of cuspal stiffness achieved by conventional glass ionomer bases was very small, whereas composite resin bases increased cuspal stability by more than a factor of two. After placement of the final restorations, however, there was no longer a difference between teeth with different base materials. Nevertheless, composite resin bases might be preferred for two reasons. Firstly, deterioration of adhesive restorations will probably start at the cavosurface margins. The incidence of margin gaps, however, will not only compromise marginal seal but also the stabilizing effect of the restoration. In this situation, the resin base may still stabilize the tooth. Moreover, resin bases may reduce the risk of cusp fracture during the time between cavity preparation and the insertion of adhesive inlays.

Aluminum Silicates↗

PubMed1950