Cornelia Frese

Recontouring teeth and closing diastemas with direct composite buildups: A 5-year follow-up

OBJECTIVES Adhesive resin composite technology enables dentists to add composite material to tooth surfaces to close gaps and reshape tooth form without cavity preparation. This option creates new possibilities for minimally invasive dentistry as the tooth shape, position and colour can be altered without loss of tooth substance. However, evidence-based data on direct composite buildups are rare. METHODS The purpose of this study was to evaluate the outcome and to document the occurrence of unfavourable events and clinical findings of 176 direct composite buildups that had been performed in the Department of Conservative Dentistry, University Hospital Heidelberg, Germany, between 2002 and 2008. Outcome was categorised as failure (F), survival (SR) or success (S). Restorations still in place and without prior failure at follow-up were qualitatively rated using modified USPHS/FDI criteria. RESULTS During the follow-up period, 30 restorations were found to have had unfavourable events or clinical findings. All restorations were repaired, and they remained in situ (SR). No complete loss (F) was recorded. The overall survival rate was 84.6% after 60 months (95%, confidence interval [CI]: 78.5 and 90.6). Clinical quality was rated excellent or good for most (>90%) of the restorations examined. CONCLUSIONS The direct composite buildups observed in this study were found to have promising clinical outcome and good quality parameters after 5 years. If a noninvasive or minimally invasive treatment approach is indicated, direct composite buildups provide an acceptable treatment alternative for the aesthetic correction and reshaping of anterior teeth. CLINICAL SIGNIFICANCE The application of direct composite buildups in clinical cases in which a non- or minimally invasive treatment approach is indicated provides an excellent treatment alternative for gold-standard treatment options like laboratory-made crowns and porcelain veneers. Restorations in the present investigation showed a functional survival rate of 100%, an overall survival rate of 84.6% after 5 years.

Original and repair bond strength of fiber-reinforced composites in vitro

OBJECTIVE A great benefit of FRC technology is that, in case of minor failure events, restorations can be repaired or reinserted. However, various FRC materials are available, that differ in matrix composition and fiber pre-treatment. The aim of this investigation was, therefore, to evaluate original and repair bond strength of FRC materials. METHODS Five fully pre-impregnated, unidirectional FRCs were selected, one semi-interpenetrating polymer network FRC and four cross-linked-polymer FRCs. The primary endpoint was the evaluation of shear bond strength (SBS) between FRC and composite resin, which was performed by a universal testing machine. For each FRC specimens were divided into control (original SBS, resin to fresh FRC with oxygen inhibition layer (OIL), n=30) and test groups (repair SBS, resin to FRC after removal of OIL and adhesive infiltration, n=30). RESULTS The cross-linked-polymer FRC GrandTec(®) (12.4±5.4 MPa) yielded the highest control SBS, followed by the semi-interpenetrating polymer network FRC (everStick(®), 9.2±3.5 MPa). With everStick(®), repair led to a significant increase in the test SBS (14.6±5.8 MPa, p=0.01). SIGNIFICANCE Control SBS was best with GrandTec(®) indicating that the material is superior in direct clinical application. Test SBS was significantly increased with everStick(®) which points at potential reparability and advantages in semi-direct or indirect fabrication of fiber-reinforced fixed partial dentures.

Effect of endurance training on dental erosion, caries, and saliva

The aim of this investigation was to give insights into the impact of endurance training on oral health, with regard to tooth erosion, caries, and salivary parameters. The study included 35 triathletes and 35 non‐exercising controls. The clinical investigation comprised oral examination, assessment of oral status with special regard to caries and erosion, saliva testing during inactivity, and a self‐administered questionnaire about eating, drinking, and oral hygiene behavior. In addition, athletes were asked about their training habits and intake of beverages and sports nutrition. For saliva assessment during exercise, a subsample of n = 15 athletes volunteered in an incremental running field test (IRFT). Athletes showed an increased risk for dental erosion (P = 0.001). No differences were observed with regard to caries prevalence and salivary parameters measured during inactivity between athletes and controls. Among athletes, a significant correlation was found between caries prevalence and the cumulative weekly training time (r = 0.347, P = 0.04). In athletes after IRFT and at maximum workload, saliva flow rates decreased (P = 0.001 stimulated; P = 0.01 unstimulated) and saliva pH increased significantly (P = 0.003). Higher risk for dental erosions, exercise‐dependent caries risk, and load‐dependent changes in saliva parameters point out the need for risk‐adapted preventive dental concepts in the field of sports dentistry.

Fiber-reinforced composite fixed dental prostheses in the anterior area: A 4.5-year follow-up

STATEMENT OF PROBLEM Currently, fiber-reinforced fixed dental prostheses (FRC FDPs) are a reliable treatment option for the restoration of single missing teeth in the anterior area. PURPOSE The purpose of this study was to evaluate the survival of direct and semidirect fabricated FRC FDPs in the anterior area and to rate the quality of the outcome. MATERIAL AND METHODS Twenty-four participants (12 men, 12 women) were included in the investigation. The prostheses were made of preimpregnated, unidirectional fiber-reinforced composite (FRC) (everStick, GC) by using a direct (n=18) or semidirect (n=6) technique. Eleven FRC FDPs had been placed in the maxilla and 13 had been placed in the mandible. Follow-up intervals were recorded, and the prostheses were classified as success (successful), survival (unfavorable event but still in vivo), or failure (lost). Quality was rated according to the modified United States Public Health Services (USPHS) or Ryge criteria. RESULTS The FRC FDPs evaluated in this study showed an overall survival rate (success) of 72.6% and a functional survival rate (success + survival) of 85.6% (median follow-up 54 months). According to the USPHS/Ryge criteria, most of the restorations displayed excellent or good quality. Survival analysis was performed by the Kaplan-Meier method. CONCLUSIONS The FRC FDPs evaluated in this study showed promising survival rates and good quality after a median follow-up period of 4.5 years (quartile range 3.5 to 6.3 years), thus indicating that FRC FDPs are reliable treatment options for the restoration of single missing teeth in the anterior area. The use of preimpregnated FRC materials with higher fiber content might improve the clinical fabrication of FRC FDPs but does not influence their long-term clinical survival.

Cytotoxicity of coated and uncoated fibre-reinforced composites

Abstract Objective. Currently, there are many fibre-reinforced composites (FRCs) available which differ in the type and volume fraction of fibres, pre-treatment of fibres and matrix composition. The aims of this in vitro investigation were to determine whether there is a difference in biocompatibility of FRCs and if coating FRCs with resin composites influences their cytotoxic potential. Materials and methods. Five different FRC materials were tested which were either uncoated or coated with flowable or viscous resin composite. Artificial saliva extracts were prepared according to USP-XXIII and ISO-10993 to determine cytotoxicity by testing cell viability and growth of primary human gingival fibroblasts (HGF) using MTT assay, LIVE/DEAD® assay and cell proliferation assay. The influence of eluates on fibres of the cytoskeleton was investigated by vimentin, tubulin and actinin immunostainings. A two-way ANOVA followed by Scheffes post-hoc test, which included the factors FRC material and coating procedure, was performed to assess cytotoxicity. Results. All extracts of FRC materials displayed minor cytotoxic potential on HGF cell viability, cell proliferation and integrity of the cytoskeleton. The type of FRC material significantly influenced cell viability (MTT assay) (p < 0.0001), whereas neither the presence of a coating nor the type of coating material resulted in altered cell viability. Distribution and organization of cytosolic fibres was not affected after HGF exposure to eluates. Conclusions. There is a lack of knowledge about the leaching behaviour of commonly available fully pre-impregnated FRCs and their interactions with coating materials. The coating of FRCs with resin composite materials did not impact biocompatibility.

A 6.5-year clinical follow-up of direct resin composite buildups in the posterior dentition: Introduction of a new minimally invasive restorative method.

OBJECTIVES Restorative rehabilitation of missing single teeth in the posterior dentition is achieved primarily by dental implants or fixed dental prostheses. Here we introduce an uncommon, minimally invasive treatment option in order to close single tooth gaps. METHODS The purpose of this study was to evaluate the clinical quality and survival of 45 direct composite buildups in the posterior dentition. A detailed clinical examination was performed, and restorations were rated qualitatively using the modified USPHS/FDI criteria. RESULTS The mean extension of the direct composite buildups was 2.96 (1.12)mm per tooth. Interdental closures from both adjacent teeth had a significantly higher extension of the direct composite buildups than one-sided interdental closures (p=0.03). Patients with a history of prior tooth loss showed a significantly greater extension of direct composite buildups than patients without prior tooth loss (p=0.006). During the follow-up period, no restoration showed unfavorable events. The overall survival rate for the direct composite buildups was 100% after median follow-up of 78.96 months. The clinical quality rating indicated that most of the restorations (>94%) displayed excellent or good quality. No periodontal destruction, signs of gingival inflammation or increased plaque accumulation was observed. CONCLUSIONS The posterior direct composite buildups evaluated in this study showed promising clinical survival data and excellent quality parameters after a median observation time of 6.5 years. CLINICAL SIGNIFICANCE If a minimally or non-invasive treatment approach is indicated, posterior direct composite buildups provide a successful treatment alternative for the closure of single-tooth gaps to implant-supported or fixed dental prostheses.

Fiber-reinforced composite fixed dental prostheses: A 4-year prospective clinical trial evaluating survival, quality, and effects on surrounding periodontal tissues

Statement of problem. Although fiber‐reinforced composite fixed dental prostheses (FRC FDPs) are a reliable treatment option for the restoration of single missing teeth, comparatively few prospective clinical trials (PCT) exist. Purpose. The purpose of this PCT was to evaluate the survival, quality outcome, and effect of FRC FDPs on periodontal health over 4 years. Material and methods. Twenty‐six consecutive patients (16 men, 10 women) receiving FRC FDPs with preimpregnated unidirectional fiber reinforcement were included in the trial. Eighteen FRC FDPs were placed in the maxilla and 8 in the mandible. Data from baseline, 12‐, 36‐, and 48‐months of follow‐up were recorded, and the prostheses were classified as “success,” “survival,” or “failure.” Periodontal parameters (probing depth, clinical attachment level, plaque index, and bleeding index were assessed, and the quality was rated according to modified United States Public Health Service (USPHS)/Ryge or World Dental Federation (FDI) criteria. Results. Functional survival at 4 years was 73.5% (95% confidence interval [CI], 52.9‐87.3) with 17 FRC FDPs still functioning. Twelve of these were classified as “success” and 5 as “survival.” Overall survival was 53.0% (95% CI, 30.4‐74.4). Six FRC FPDs failed completely. Periodontal parameters did not change over the observation period. Regression analysis showed that probing depth and clinical attachment level did not influence the survival of FRC FDPs. According to USPHS/Ryge/FDI criteria only “wear” and “surface luster” increased significantly over 4 years. Conclusions. The survival rate of FRC FPDs confirms existing data. Negative effects on periodontal health were not seen over the period of observation. Aging effects such as wear were recorded and indicated that FRC FPDs are at risk of disintegration, as they are composed of a fiber framework and veneering composite resin.

Biological evaluation of subgingivally placed direct resin composite materials

Placement of composite resin restorations in deep subgingival cavities can damage surrounding soft tissues. In addition, commonly used resin-based composites (RBCs) might interfere with wound healing and periodontal health. To clarify cellular interactions with RBCs, we used an MTT assay to investigate adhesion of primary human gingival fibroblasts and human osteoblasts (hFOB 1.19) on five RBC materials with and without surface modifications (alumina blasting with 50- or 110-μm Al2O3). In addition, high-performance liquid chromatography (HPLC) was used to determine release of resin monomers from RBCs after 1 h, 1 day, and 7 days. As compared with tissue culture plastics (the control), cellular adhesion was significantly lower (P < 0.001) for human gingival fibroblasts and osteoblasts. Only minor, nonsignificant differences between individual RBCs were identified. HPLC analyses identified the release of three bifunctional methacrylates bisphenol A glycerolate dimethacrylate, triethylene glycol dimethacrylate, and diurethane dimethacrylate from RBCs and showed that monomer release increased between 1 h and 1 day but remained low. The present findings suggest that surface adhesion in the subgingival area is limited for the tested RBCs. Although residual monomer release was low for all tested RBCs, it might be sufficient to adversely affect cell adhesion.