Human pulp response to resin cements used to bond inlay restorations.

OBJECTIVE: The aim of this study was to evaluate the pulp response following cementation of inlays using two different resin cements. METHODS: Deep Class V cavities were prepared on the buccal surface of 34 sound human premolars. Impressions were taken and inlays were prepared which were cemented with the following luting materials-Group 1: Rely X Unicem (3M ESPE); Group 2: Variolink II (Ivoclar Vivadent). In Group 3 (control), after lining the cavity floor with Dycal (Dentsply Caulk) the inlays were cemented with Rely X Unicem. Four additional teeth were used as an intact control group. For Variolink II, the adhesive system Excite was used as part of the cementation procedure. After 7 or 60 days, the teeth were extracted and processed for histological assessment. RESULTS: At 7 days, Rely X Unicem and Variolink II system triggered in two samples a mild and moderate inflammatory response, respectively. At 60 days, the pulpal response decreased for both groups. A discrete persistent inflammatory response occurred in Group 2 in which displacement of resin components across the dentin tubules was observed. In the control group, normal histological characteristics were observed. The inflammatory response and tissue disorganization were related to the remaining dentin thickness between the cavity floor and the pulp tissue. SIGNIFICANCE: Techniques for inlay cementation using distinct luting cements may cause specific pulpal damage. Variolink II associated with the adhesive system Excite cause more aggressive effects to the pulp-dentin complex than Rely X Unicem cement when both are used to cement inlay restorations.

Clinical evaluation of a resin-modified glass-ionomer liner for cervical dentin hypersensitivity treatment.

PURPOSE: To evaluate the effectiveness of two agents for treating cervical dentin sensitivity associated with gingival recession or noncarious cervical lesions. METHODS: 44 patients with at least mild sensitivity affecting cervical dentin were enrolled in a longitudinal randomized clinical trial. A resin-based desensitizer or an experimental glass-ionomer was assigned to treat at most two teeth from each side of the mouth. Sensitivity was assessed by tactile and cold tests, measured with a Visual Analogue Scale at baseline, after treatment, and at 1 week, 1, 3, 6, and 12 months after treatment. Other noteworthy clinical observations were recorded. RESULTS: Both treatments effectively reduced dentin sensitivity (mixed linear model analysis). Sensitivity score for the glass-ionomer was significantly lower than for the resin-based desensitizer after treatment and at all follow-up periods (P < 0.0001). Some overhanging margins were observed in the glass-ionomer group, which could accumulate plaque and cause gingivitis. Despite material loss from some teeth treated with the glass-ionomer, the follow-up sensitivity scores were still lower than baseline scores.

In vitro cuspal deflection and microleakage of maxillary premolars restored with novel low-shrink dental composites.

OBJECTIVES: The development of novel low-shrink resin-based composites (RBCs) may offer a potential reduction in polymerisation shrinkage stresses generated at the tooth/restoration interface compared with current methacrylate RBCs. In vitro cuspal deflection and microleakage of meiso-occlusal-distal (MOD) cavities restored with experimental oxirane and silorane (EXL596 and H1) and methacrylate (Z100 and Filtek Z250) RBCs were assessed. METHODS: Standardised pre-molar MOD cavities were prepared (n = 10) and restored with each material. The flexure of buccal and palatal cusps was recorded 0.1 h following irradiation utilising a differential transformer deflection gauge. Each restored tooth was subjected to a thermocycling regime and microleakage of tooth sections were assessed following 24 h immersion in 0.2% fuschin dye. The degree of conversion (DC) of each RBC material was also assessed using Fourier transform infrared (FTIR) spectroscopy following 0.1, 0.5, 1, 4, 24 and 48 h post-irradiation. RESULTS: A total cuspal deflection was observed for EXL596 (2.5 +/- 0.9 microm) and H1 (6.0 +/- 1.8 microm) compared with Z100 (20.0 +/- 4.7 microm) and Filtek Z250 (16.5 +/- 3.3 microm) following 0.1 h. The cavities restored with EXL596 displayed significantly higher microleakage than any other RBC and H1 exhibited non-significant and significantly decreased microleakage compared with Z100 and Filtek Z250, respectively. The DC of EXL596 and H1 was significantly decreased compared with Z100 and Filtek Z250 following 0.1, 0.5 and 1 h. SIGNIFICANCE: The 'living' polymerisation associated with the novel oxirane and silorane RBCs and the associated decrease in cuspal deflection may suggest a decrease in the magnitude of polymerisation shrinkage stress at the tooth/restoration interface. The decreased DC following 0.1 h of the oxirane compared with the methacrylate RBCs has provided information on the cure rate of cationic and free-radical polymerisation mechanisms, respectively. The inadequate marginal seal of cavities restored with EXL596 would preclude its use as a dental restorative. The reduction in cuspal deflection and decrease in microleakage of cavities restored with H1 compared with Filtek Z250 may be advantageous in terms of marginal integrity following placement. However, the non-significant difference in microleakage between the H1 and Z100 may only present modest decreases in the deleterious effects of shrinkage stress.

The reliability in flexural strength testing of a novel dental composite.

OBJECTIVES: To investigate the reliability of bi-axial flexure and three-point flexure testing of an experimental, low-shrink oxirane-based dental composite, EXL596 compared with two conventional methacrylate based restoratives, Z250 and Z100. METHODS: Specimens (n=20) of a novel oxirane-based composite and two commercially available methacrylate based composites were fabricated for flexural testing to evaluate mean bi-axial flexure strengths, three-point flexure strengths and the associated Weibull moduli (m) following 24 h immersion in a lightproof waterbath maintained at 37+/-1 degrees C. RESULTS: Mean bi-axial flexure strengths and the associated m of EXL596, Z250 and Z100 were 168+/-11 MPa (m=16.2+/-4), 140+/-12 MPa (m=11.9+/-3) and 126+/-13 MPa (m=10.2+/-2), respectively. Three-point flexure strengths and the associated m of EXL596, Z250 and Z100 were 113+/-15 MPa (m=9.2+/-2), 92+/-10 MPa (m=8.5+/-2) and 79+/-16 MPa (m=6.3+/-1), respectively. CONCLUSIONS: The present investigation suggests that bi-axial flexure strength testing of dental resin-based composites provides a more reliable testing method than three-point flexure. The increased reliability was considered in terms of the associated Weibull moduli following bi-axial flexure testing as a result of the elimination of the additional induced variability introduced during the curing regime of three-point flexure specimens.

Monomer conversion versus flexure strength of a novel dental composite.

OBJECTIVES: To quantify the monomer conversion and flexural strength of an experimental oxirane-based composite material (EXL596) compared with two, commercially available, dimethacrylate based restoratives (Z250 and Z100). METHODS: Fourier-transform infra-red spectroscopy (FTIR) was utilised to evaluate the degree of conversion (DC) (n=5) and biaxial flexure strength (BFS) testing (n=20) was used to analyse flexural strength and associated Weibull moduli (m) of each material following 0.1, 0.5, 1, 4, 24 and 48 h immersion in a lightproof waterbath maintained at 37+/-1 degrees C. RESULTS: The DC of Z250 and Z100 following 0.1, 0.5 and 1 h post-irradiation was significantly greater than the DC of EXL596 for the same immersion periods. This was manifested as a significant decrease in BFS and associated m of EXL596 compared with Z250 and Z100 for the 0.1, 0.5 and 1 h post-irradiation periods. The DC and BFS of EXL596 were significantly greater than Z250 and Z100 following 24 h immersion. CONCLUSIONS: Assessment of FTIR spectra, BFS and associated m has provided a useful method in the quantitative analysis of resin-based composite conversion. Identification of the decreased DC of EXL596 compared with Z250 and Z100 was achieved using FTIR. However, decreased conversion rates within the first hour following irradiation of EXL596 may compromise flexural strength properties (associated with a decrease in BFS and m) which may be inadequate under masticatory loading.

Ethics of esthetic dentistry.

Patient demand for esthetics has increased globally, and often for reasons of patient self-esteem. However, important ethical issues encompass treatment for purely esthetic reasons. Also, perceptions of what is esthetic differ among patients and clinicians. Therefore, the aim of this article is to make suggestions regarding some of the issues surrounding the ethical, esthetic treatment of patients, as well as present three cases illustrating the different meanings of esthetic health to different people.

Preformed metal crowns for primary and permanent molar teeth: review of the literature.

The aim of this study was to carry out a review of the use and efficiency of preformed metal crowns (PMCs) for primary and permanent molar teeth. A literature search of English language journals was carried out using MEDLINE. Papers that addressed areas related to the use of PMCs regarding indications for use, placement techniques, risks, longevity, cost effectiveness and utilization were included in the review. Eighty-three papers were traced which fulfilled the above criteria, the majority addressing PMCs in primary molar teeth. Over half the papers were concerned with placement techniques and indications for use, with fewer papers reporting on clinical studies. The clinical data on PMCs spanned a considerable number of years and involved heterogeneous populations of patients, different makes and designs of crown, and differences among the operators and evaluators who were involved in the studies. The results, however, were in agreement that PMCs are superior to amalgam restorations for multisurface cavities in primary molar teeth.

Dentists' perceptions of trends in restorative dentistry in the UK.

PURPOSE OF STUDY: To obtain responses to a questionnaire on likely trends in the clinical practice of restorative dentistry from a national sample of general dental practitioners (GDPs) who were principals of group practices in the UK. BASIC PROCEDURES: A panel of nine experts had been convened previously to define areas of trends in restorative dentistry in the UK and to formulate these into statements. Twenty trends were identified and framed into a 22-item questionnaire based on the trend statements. The questionnaire was sent to a national sample of 2800 principal dentists in group practices. Names of principal dentists were taken from the Yellow Pages directories, a group practice being defined as at least one principal dentist and one other practitioner. Levels of agreement for questionnaire scores of > or = 70% for all segments of a statement were taken as indicating a possible trend. MAIN FINDINGS: Of the 2800 questionnaires sent out, 1448 were returned, a return rate of 52%. Of these, 1217 questionnaires were usable, an overall response rate of 44%. Good agreement was obtained for 14 statements (64%). PRINCIPAL CONCLUSION: The 14 trend statements that scored a level of good agreement were taken as indicating possible trends in dentistry in the UK as perceived by those GDPs who responded to the questionnaire. However, in view of the fact that the 1217 usable questionnaires received reflected the opinions of 10% of the principal dentists in group practice in the UK, this will not be representative of all principal dentists in practice. Nevertheless for the purposes of gaining some insight into trends in restorative dentistry, it could be considered to be of value.

Pulp response after application of two resin modified glass ionomer cements (RMGICs) in deep cavities of prepared human teeth.

OBJECTIVES: This study evaluated the human pulp response to the application of two RMGICs in deep cavities in vivo. METHODS: The cavity floor prepared on the buccal surface of 34 premolars was lined with VBP (VBP), Vitrebond (VB) or Dycal® (DY), and restored with composite resin. Additional teeth were used as an intact control group. After 7 or 30-60 days, the teeth were extracted and processed for histological evaluation. The following histological events were scored: inflammatory response, tissue disorganization, reactionary dentin formation and presence of bacteria. RESULTS: At 7 days, VBP and VB elicited a mild inflammatory pulpal response in about 70% of specimens and in 1 specimen for DY. Only 1 specimen of each RMGICs exhibited moderate tissue disorganization. Bacteria and reactionary dentin formation were not found. At 30-60 days, about 20% of specimens lined with RMGICs showed a persistent mild inflammatory pulp response while no inflammatory reaction was observed for DY. Moderate tissue disorganization occurred with both materials. Bacteria were found only in 1 VBP specimen. The mean remaining dentin thickness (RDT) in specimens lined with VBP, VB or DY ranged from 342.3 to 436.1µm, and no statistically significant differences in RDT were found among materials or periods (two-way ANOVA, p>0.05). Comparison of the two RMGICs tested for the histological events at each period showed statistically similar results (Kruskal-Wallis, p>0.05). SIGNIFICANCE: The use of the new Vitrebond formulation (VBP) in deep cavities in vivo caused mild initial pulp damage, which decreased with time, indicating acceptable biocompatibility.