Proximal contact tightness between direct-composite additions in the posterior dentition: an in vitro investigation.

PURPOSE: The aim of the study was to test whether a novel three-step matrix technique for posterior direct-composite additions creates sufficiently strong proximal contacts. MATERIALS AND METHODS: Contact tightness was measured between direct-composite additions and between original teeth on a model. Therefore, the frictional forces required to remove a straight, 0.05-mm-thick, metal matrix band inserted between adjacent teeth and held by a universal testing machine (Zwicki, Zwick GmbH, Ulm, Germany) were recorded. Measurements were taken at three time points to carry out reference analysis: at baseline, after removal of the maxillary right second premolar (tooth #15) to simulate a diastema, and after closure of the diastema by inserting two direct-composite additions with the three-step matrix technique on the maxillary right first premolar (tooth #14) and first molar (tooth #16). Measurements were performed in the maxillary right (first) and left (second) quadrants to document sagittal displacement. RESULTS: The original contact tightness values were between 1.65 ± 0.88 N and 3.05 ± 0.60 N in the first quadrant and between 1.23 ± 0.51 N and 2.18 ± 0.43 N in the second quadrant. After removal of tooth 15, values decreased significantly in the first quadrant and insignificantly in the second. After reconstruction, the contact tightness between teeth 14 and 16 was significantly stronger (tighter) (3.20 ± 0.80 N) than the originally measured contact tightness between teeth 14 and 15 (2.86 ± 0.64 N) and teeth 15 and 16 (1.65 ± 0.88 N) (p=0.006 and 0.001, respectively). CONCLUSIONS: Within the limitations of an in vitro investigation, this study has shown that by using a novel, three-step matrix technique, direct posterior composite additions can form sufficiently tight proximal contacts.

Fiber-reinforced composite fixed dental prostheses: a retrospective clinical examination.

PURPOSE: To obtain survival data on 32 fiber-reinforced fixed dental prostheses which were inserted in our department and to rate the quality of these restorations on the basis of esthetic, biological, and functional parameters. MATERIALS AND METHODS: Thirty-two patients with fiber-reinforced fixed dental prostheses were included in the study. The fiber frameworks were made of a polymer-monomer-preimpregnated continuous unidirectional glass fiber material. The survival times, failure events, and clinical parameters were recorded. Restorations in function without previous failure were classified as "Overall Survival". The classification "Functional Survival" was assigned in the event of minor failure and subsequent repair. Loss of the restoration was regarded as "Failure". The quality rating was performed using modified USHPS/Ryge criteria. RESULTS: The follow-up interval ranged from 2 to 64 months with a median follow-up time of 18.2 months. Twenty-four restorations were classified as "Overall Survival", seven were classified as "Functional Survival", and one was classified as "Failure". The overall survival at the median follow-up time was 74.4%. For the majority, the quality rating (USHPS/Ryge criteria) yielded clinically excellent results in all categories. No restoration was rated as insufficient or poor. CONCLUSION: Fiber-reinforced composite fixed dental prostheses provide sufficient stability and very good esthetic, biological, and functional performance in the case of specific clinical indications.

Analysis of the interdiffusion of resin monomers into pre-polymerized fiber-reinforced composites.

OBJECTIVES: The aim of the study was to analyze the dissolving depth of adhesive resin monomers into pre-polymerized fiber-reinforced composites (FRC) with either a semi-interpenetrating polymer network (semi-IPN) or a cross-linked polymer (CLP) matrix. METHODS: Five unidirectional FRCs were tested, including one semi-IPN FRC (everStick(®) C&B, StickTech, (ES)) and four CLP-FRCs (GrandTec(®), VOCO, (GT); Dentapreg(®), ADM, (DP); TenderFiber(®), Micerium, (TF); Splint-It(®), Pentron Clinical Technologies, (SI)). The FRCs were light-polymerized following manufacturers' instructions: the oxygen inhibition layers were removed and the adhesive resin (Optibond-FL(®), KerrHawe) was labeled with a fluorescent dye (Rhodamine-B-isothiocyanate), which was then applied to the FRCs (5 min) and light-polymerized (40s). Specimens were then prepared for confocal laser scanning microscopy. Three FRC strands per group were sectioned orthogonally to the direction of fibers, thus forming nine slices in each group. Four images were taken from each slice and the depths of adhesive penetration were measured in four sites per image (n=144 measurements per group). SIGNIFICANCE: Dissolving depths were 17.28 (3.04) µm (ES), 12.58 (2.94) µm (SI), 7.57 (1.91) µm (TF), 3.27 (0.73) µm (DP) and 2.55 (0.63) µm (GT). Samples were normally distributed. Differences between groups were analyzed by ANOVA (PostHoc Scheffé) showing four subgroups (p=0.05). The infiltration layers detected were either continuous/homogenous (ES, TF, DP GT) or discontinuous/insular (SI). CONCLUSION: The adhesive resin monomers were able to diffuse significantly deeper into pre-polymerized semi-IPN specimens than into CLP materials. Semi-IPN specimens showed a homogenous and comparatively deeper layer of infiltration. The diffusion capabilities of secondary-IPN formation might increase the opportunity to establish a good bond between pre-polymerized FRC and new resin.

Relationship between microtensile bond strength and submicron hiatus at the composite-dentin interface using CLSM visualization technique.

OBJECTIVES: "Submicron hiatus" represents a potential space between the base of the collagenous network and the mineralized dentin when it is acid etched for bonding. This study evaluated the relationship between microtensile bond strength (microTBS) and occurrence of submicron hiatus formations at the resin-dentin interface using the same specimens. METHODS: Resin-dentin bonded micro-specimens (sticks with a size of 300 microm x 300 microm x 8mm) were prepared using one of two material combinations (group I: Syntac Classic/Tetric Ceram Cavifil: n=51 group II: Prime & Bond NT/Tetric Ceram Cavifil: n=56). After labeling the primer component with a tiny amount of rhodamine-B-isothiocyanate, submicron hiatus formations were imaged nondestructively using a confocal laser scanning microscope (CLSM). Subsequently specimens were subjected to a microTBS test. RESULTS: For the influence of submicron hiatus formations on microTBS with the Syntac Classic group, the nonparametric Spearman's correlation was -0.329 at p=0.02. For the Prime & Bond NT group, the nonparametric Spearman's correlation was -0.356 at p=0.007. Analyzing the effect of submicron hiatus on without discriminating by group resulted in a Spearman's correlation coefficient of -0.341 at p=0.001; microTBS and quality of hybrid layer showed a correlation coefficient of 0.849 at p=0.001, and microTBS and quality of tag formation showed a correlation coefficient of 0.474 at p=0.001. SIGNIFICANCE: The degree of submicron hiatus formations had an influence on microtensile bond strength for both the Syntac Classic and the Prime & Bond NT group.

Recontouring teeth and closing diastemas with direct composite buildups: a clinical evaluation of survival and quality parameters.

OBJECTIVES: Irregular tooth shape and position in the anterior maxilla and mandible are major aesthetic problems for patients. In recent years such conditions have increasingly been treated minimally or even non-invasively by recontouring teeth with direct composite resin buildups. Although clinical experience with this treatment option is promising, evidence-based data about longevity are limited. METHODS: The authors evaluated survival and quality of 327 composite buildups that were placed in 101 patients in the Department of Conservative Dentistry, University of Heidelberg, between 2002 and 2008. Follow-up intervals and failures were recorded. Quality was assessed by grading restorations (modified USPHS/Ryge critera) still in situ without adverse event during the follow-up period. RESULTS: After a mean follow-up interval of 27.8 months, 284 restorations were in situ and had no event. Forty-two restorations were in situ but had events that were mostly minor fractures of the composite resin. One restoration had been lost. Analysis of the time from insertion to any event or end of follow-up yielded an estimated 5-year survival rate of 79.2% (95% CI, 70.5-87.9). Quality was assessed by grading in situ restorations without event. More than 90% of graded restorations were categorized as "clinically excellent" (1) or "clinically good" (2). A correlation between those rated "clinically sufficient" or worse (≥3) and the follow-up period was observed. CONCLUSIONS: Direct composite buildups are aesthetic, functional, and biologically sound treatment options for recontouring teeth and closing diastemas with clinically promising survival rates. Therefore, tooth shape correction can be recommended in cases in which minimally invasive or non-invasive procedures on healthy teeth are indicated.

Mineral trioxide aggregate or calcium hydroxide direct pulp capping: an analysis of the clinical treatment outcome.

INTRODUCTION: The use of mineral trioxide aggregate (MTA) might improve the prognosis of teeth after pulp exposure. The treatment outcome of teeth after direct pulp capping, either with mineral trioxide aggregate (MTA) or calcium hydroxide (controls), was investigated, taking into account possible confounding factors. METHODS: One hundred forty-nine patients treated between 2001 and 2006 who received direct pulp capping treatment in 167 teeth met the inclusion criteria. Treatment was performed by supervised undergraduate students (72%) and dentists (28%). Assessment of clinical and radiographic outcomes was performed by calibrated examiners 12-80 months after treatment (median, 27 months). RESULTS: One hundred eight patients (122 treated teeth) were available for follow-up (72.5% recall rate). A successful outcome was recorded for 78% of teeth (54 of 69) in the MTA group and for 60% of teeth (32 of 53) in the the calcium hydroxide group. The univariate analysis (generalized estimation equations model [GEE model] showed a significant difference in the success rate (odds ratio [OR], 2.36; 95% confidence interval [CI], 1.05-5.32; P = .04). In the multiple analysis (GEE model), the OR is marginally inside the nonsignificant range (OR, 0.43; 95% CI, 0.19-1.02; P = .05) when conspicuous confounding factors are stabilized (univariate analysis). Multiple analysis showed that teeth that were permanently restored >or=2 days after capping had a significantly worse prognosis in both groups (OR, 0.24; 95% CI, 0.09-0.66; P = .01). CONCLUSIONS: MTA appears to be more effective than calcium hydroxide for maintaining long-term pulp vitality after direct pulp capping. The immediate and definitive restoration of teeth after direct pulp capping should always be aimed for.

Relationship between microtensile bond strength and nanoleakage at the composite-dentin interface.

OBJECTIVES: This study evaluated the relationship between microtensile bond strength (microTBS) and occurrence of nanoleakage at the resin-dentin interface using the same specimens. METHODS: Resin-dentin-bonded micro-specimens (sticks with a size of 300 microm x 300 microm x 8mm) were prepared using one of two material combinations (group I: Syntac classic/Tetric Ceram Cavifil: n=57; group II: Prime & Bond NT/Spectrum TPH: n=52). After immersion of the micro-specimens in 0.1% rhodamine-B solution for 1h, nanoleakage was imaged nondestructively using a confocal laser scanning microscope (CLSM). Then the specimens were subjected to a microTBS test. RESULTS: For the influence of nanoleakage on microTBS with the Syntac classic/Tetric Ceram Cavifil group, the nonparametric Spearman correlation was 0.033 at p=0.805. For the Prime & Bond NT/Spectrum TPH group, the nonparametric Spearman correlation was 0.077 at p=0.584. SIGNIFICANCE: The degree of nanoleakage had no influence on microtensile bond strength for the Syntac classic/Tetric Ceram Cavifil or for the Prime & Bond NT/Spectrum TPH group.