Direct resin composite restorations for fractured maxillary teeth and diastema closure: A 7 years retrospective evaluation of survival and influencing factors

Abstract

Objectives

This retrospective study evaluated the survival rate of anterior direct resin based composite (RBC) build-ups in vital teeth made of microhybrid and nanofill RBC materials and the influence of bruxism, beverage consumption and smoking on the long-term performance of restorations.

Methods

Patients receiving anterior restoration between 2006 and 2011, with the diagnosis of fracture or diastema, were selected. A total of 65 adult patients (mean age: 25.2) with 163 restorations (78 Filtek Supreme XT and 85 Enamel Plus HFO) were evaluated using the USPHS criteria. Data were analyzed with Fisher’s Exact Test, Extended Cox-regression analysis and Kaplan–Meier method.

Results

Mean observation period was 7.2 (±1.4) years and the mean annual failure rate for this period was 1.43%. The reasons of failures included restoration fracture and color mismatch. Nanofill restorations had significantly higher rate of color mismatch (p = 0.002), microhybrids more frequently failed in fracture of restoration (p = 0.034). The overall difference in potential hazard of using Enamel Plus HFO or Filtek Supreme XT was not significant (p = 0.704). Chipping or fracture of the restoration was more frequent in the first year after placement (p = 0.036), while beverage consumption was significantly correlated with discoloration of the restorations (p = 0.005).

Significance

The application of direct RBC restorations provides an excellent treatment option for fractured teeth and for closing diastemas. The overall survival rate was 88.34% up to 10 years. Microhybrid and nanofill RBC restorations showed similar survival rates, however nanofills discolored at a higher rate, meanwhile chipping of the restoration occurred frequently with microhybrids.

Introduction

Patients suffering from an anterior fracture, attrition, diastema or dental malformation and malposition should be provided with adequate esthetic correction including orthodontic treatment, indirect ceramic or direct resin based composite (RBC) restorations. Recently, with the continuous development of adhesives and RBC technology the state-of-the-art treatment option in operative dentistry for the esthetic improvements of healthy teeth – especially for adolescents and young adults with intact enamel – can be non-invasive or at least minimally invasive . Beside the excellent esthetic and mechanical features of the different types of RBCs, the dentist’s skill in achieving a natural anatomical shape, surface texture and shade is also a prerequisite for an esthetically pleasing result. Compared to ceramic restorations the direct applications with RBCs have several benefits, such as quickness, cheapness and easy of repair. Currently, RBC is the first choice material to restore anterior and posterior teeth .

Clinical data on the performance of posterior RBC restorations are indicating low annual failure rates (AFRs) and long-lasting survival . In contrast, despite the general application of RBCs in the anterior region, there is a lack of evidence from clinical trials especially regarding the long term performance of non-carious anterior restorations. These direct tooth-shaped restorations seem to be used increasingly in clinical practice with excellent short-term results . However, a demand for knowledge still exists regarding the potential influencing factors for failure in the long-term. The main reported reasons for failure in posterior teeth are secondary caries and fracture with 70–98% survival rate after 8 and 22 years . However, in contrast, caries is not a major cause for failure of anterior restorations . In studies looking at build-ups or direct veneers esthetic failures were more frequently observed, where color alterations, surface staining, and marginal discoloration could negatively influence the patient’s perception of the restoration . On the other hand, Wolff et al. and van Dijken et al. found that the most frequent threat to direct composite build-ups is the fracture of the RBC . In case of chipping, due to the composite’s material properties, a simple repair can be performed to extend the life of the original restoration. These unfavorable events could be classified in the evaluation process as survival. The 3–5 years survival of anterior restorations could vary between 79–89% . However, the potential influence of formulation characteristics of RBC, the size of the build-ups, the patient’s factors and operator characteristics remain to be determined, especially in long-term clinical trials. Kubo et al. investigated only the factors associated with the longevity of Class III, IV and V RBC restorations with respect to the gender, age, operator factor, cavity type and retreatment risk . They concluded that operator factor, cavity type and retreatment risk had significant influence on the survival time. Focusing on the material, Gresnigt et al. compared two microhybrid RBC materials in their short-term study and did not find differences in the longevity .

There are several research techniques for the assessment of restoration longevity. Among others these include retrospective, prospective studies, randomized controlled clinical trials, cohort studies and cross-sectional analysis. The biggest challenge for long-term studies is the wear out of the study populations. Retrospective longitudinal studies in particular allow us observation times of more than 10 years, while also enabling us to examine many restorations in a relatively short time . However, retrospective studies do seem to be inferior to prospective ones in certain aspects. In the former design there is an obvious lack of standardization of indication and treatment protocols. Although, if the conditions are set out well at the start, and the number of examining operators are kept to a minimum, the potential of a certain type of restoration can still be reflected .

The purpose of this retrospective study was to investigate the failures and estimate the survival of direct RBCs placed for the restoration of fractured maxillary anterior teeth or placed for closing diastemas according to the modified USPHS criteria, in clinical practice using a nanofill RBC and a microhybrid RBC. Factors thought to be associated with failure such as the size of the build-up, bruxism, dietary habits and smoking were also examined for up to ten years.

Material and methods

Study design and participants

The database with clinical records from the Operative Dentistry Department at the University of Pécs was used in the present evaluation. From this database, all patients who had received direct RBC restoration in the maxillary anterior teeth by the first author (E.L.) for fracture or diastema closure (including peg-shaped lateral incisors) were selected for this retrospective analysis. The study protocol was approved by the Regional Research Ethics Committee of University of Pécs (3410.1./2009). All patients were contacted by phone or mail. Those patients who were able to participate in the study, signed a written, informed consent prior to the start of the clinical evaluation.

Inclusion and exclusion criteria

For this retrospective study, a total of 65 patients with ages ranging from 18 and 58 years old (25 males and 40 females, mean age: 25.2 at the time of restoration placement) were selected according to pre-determined inclusion criteria from the registers of a Hungarian clinical practice (University of Pécs), from June 2006 to December 2011, securing a minimum observation period of 5 years and the longest one of 10 years. The selected patients received a total of 163 direct RBC build-ups in their vital maxillary teeth. 70 central incisors and 22 lateral incisors were restored with the indication of fracture. Diastema closure was performed in 32 cases in central incisors, 31 cases in lateral incisors (including peg-shaped lateral incisors, n = 5) and 8 cases in canine. Information was given to each participants regarding the alternative treatment options. The inclusion criteria employed comprised of the following: all participants were at least 18 years old, able to read and sign the informed consent document, physically and psychologically able to tolerate the procedure. Furthermore, patients who were selected for the study had full dentition and normal occlusion without generalized periodontal disease, as verified by the clinical and radiographic records, and these patients had remained in continuous clinical follow-up, including at least 1 annual recall without attending other dentists. Reasons for placement of direct RBC build-ups were either fracture of the tooth or diastema, including peg-shaped lateral malformation correction as well or changing old restorations with the same dental history. Margins placed on enamel was a requirement, had to be fulfilled in order for the placement of direct RBC. Endodontically treated teeth at baseline were excluded from the study, however the necessity of endodontic treatment after build-up was recorded from the documentation during the evaluation. Dental history of the restorable tooth was recorded from the clinical documentation. The extension of the RBC restoration was grouped as following: <25%, 25–50% or >50% of the entire anatomical crown.

Restorative procedures

The brands, types, manufacturers, chemical compositions of the materials used in this study are listed in Table 1 .

Table 1
The brand, type, manufacturer, chemical composition of the materials used in this study.
Brand Type Manufacturer Chemical composition
Filtek Supreme XT Nanofill composite 3M ESPE, St Paul, MN, USA BisGMA, UDMA, TEGDMA, PEGDMA, 72.5 w% (55.6 v%) non-agglomerated/non-aggregated 20 nm silica and 4–11 nm zirconia filler, 0.6–20 μm aggregated cluster fillers
Enamel Plus HFO Micro-hybrid composite Micerium S.p.A., Avegno, Italy BisGMA, TEGDMA, UDMA, 1,4-butandiol-dimethacrylate, 75 w% (53 v%) 0.7 μm glass filler and highly dispersed 0.04 μm silicone dioxide
Adper Single Bond Total-etch adhesive 3M ESPE, St Paul, MN, USA BisGMA, UDMA, HEMA, glycerol 1,3-dimethacrylate, methacrylate functional copolymer of polyacrylic and polyitaconic acids, 10% 5 nm silane treated colloidal silica
Ultra-Etch Phosphoric acid Ultradent Products Inc, South Jordan, UT, USA 38% phosphoric acid
Abbreviations; BisGMA: bisphenol A diglycidil ether dimethacrylate; UDMA: diurethane dimethacrylate; TEGDMA: triethylene glycol dimethacrylate; PEGDMA: polyethylene glycol dimethacrylate.

All RBC restorations were performed by the first author (E.L.) specializing in restorative dentistry. Operative procedures were performed under local anesthesia if it was necessary. Few of the restorations were placed free-hand using Mylar strip, but most anterior build-ups were placed with the aid of a silicon stent constructed from a diagnostic wax-up. All RBCs had been placed following the principle of minimally invasive dentistry. Before tooth preparation the teeth were cleaned with pumice and the shade selection was performed with Vitapan Classical Shade Guide (Vita Zahnfabrik, Bad Säckingen, Germany) according to the corresponding shade selector for Filtek Supreme XT and chromatic chart for Enamel Plus HFO . The bonding surfaces of the teeth were roughened with abrasive discs (Sof-Lex Contouring and Polishing Discs, 3M ESPE, St. Paul, MN, USA). In case of fracture, the unsupported enamel was removed with a red diamond needle-shaped bur (Dentsply Maillefer, Ballaigues, Switzerland) and a long bevel (includes all enamel and up to half of the exposed dentin) was prepared on the buccal surface under constant water cooling. All margins were placed supra-gingivally to maintain good periodontal health. The teeth were isolated mostly with conventional rubber dam technique or with split dam technique or in some cases with lip retractor and cotton rolls. Regarding the adhesive technique, a two-step etch-and-rinse system was used for each restoration. The teeth were conditioned with total etch technique by applying 38% phosphoric acid (Ultra-etch, Ultradent, South Jordan, UT, USA). The acid gel was first applied on the enamel for 10 s, followed by 10 s on both dentin and enamel. After 20 s rinsing and careful drying of the cavity with air was performed (wet bonding technique), one step enamel-dentin adhesive system (Adper Single Bond, 3M ESPE) was applied as per manufacturer’s instructions by rubbing the dentin and enamel with a micro-brush soaked in the resin. In order to evaporate the solvent, gentle, 10 s air-drying was carried out, followed by polymerization with a light emitting diode (LED) curing unit ( λ = 420–480 nm; LED.C, Woodpecker, Guilin, China) with 20 s exposure time at a light intensity of 1100 mW cm −2 and with an irradiated diameter of 10 mm.

One microhybrid (Enamel Plus HFO, Micerium S.p.A., Avegno, Italy) and one nanofill (Filtek Supreme XT, 3M ESPE) RBC were used randomly, placed with layering technique. The restorations were gradually built up with a multilayer technique of dentin and enamel shades, additional “effect” shades with different opacity and translucency were applied when it was necessary for the natural appearance. Each enamel shade layer was light-cured for 20 s, dentin shade layer for 40 s using the LED unit. The occlusion was checked in protrusive movements of the mandible. The final polishing was performed with fine-grit diamond burs to remove gross excess, followed by polishing with abrasive discs (Sof-Lex Finishing strips, 3M ESPE) and with aluminum oxide strips (Sof-Lex Finishing strips, 3M ESPE) for the interproximal surfaces. Finally, polishing brushes (Shiny S, Micerium S.p.A., Avegno, Italy) were used for the natural gloss until all restorations were considered clinically acceptable.

Evaluation and statistical analysis

The restorations were evaluated between June and September 2016 by two calibrated examiners using dental mirror and explorer, in accordance with modified United States Public Health Service (USPHS) criteria ( Table 2 ) . The dentists were trained and calibrated before the start of the evaluation. Cohen’s kappa statistic was used to calculate observer agreement. Intraobserver (kappa values of 0.77 and 0.79) and interobserver’s (a kappa value of 0.82) agreement was found excellent in this study. The history of the restorations was investigated from the dental records. If a restoration had failed, resulting in either replacement or repair, it was considered as failure, and both the data and the reason for failure were recorded. Caries in a non-filled surface of a tooth with an acceptable RBC restoration was not considered reason for failure. Patient variables recorded at baseline were age and gender, the consumption of coffee/tee/cola, smoking and bruxism. Individuals who before the examination reported smoking and consumption of any type of beverages with discoloring effect (coffee, tea, cola) at least once per day during the year were classified as current smokers and/or beverage consumers. The diagnosis of bruxism is based particularly on history, tooth mobility, tooth wear (attrition or chipping) and other clinical findings. For history taking the patients had to fill a questionnaire where questions were focusing on the night or awake grinding, jaw fatigue on awakening or on the experience temporal headache. The clinical examination covered the detection of tooth wear seen within the normal range of jaw movements or especially at eccentric position. Masseter muscle hypertrophy, masticatory muscle discomfort, tooth hypersensitivity to cold, tooth abfraction, clicking of the temporomandibular joint and tongue or cheek indentation. Also “possible” bruxers were considered to have bruxism. For the tooth examination the surface was dried with an air stream before evaluation, except for color scoring. Approximal surface control was performed with the help of a dental floss. In order to avoid unnecessary radiation exposure radiographs were only made in those cases when the clinical examination indicated so and it was necessary for the completion of the examination .

Table 2
List of modified United States Health Service (USPHS) criteria used for the clinical evaluations of the restorations.
Category Score Criteria
Acceptable Unacceptable
Marginal adaptation 0 Smooth margin
1 All margins closed or posses minor voids, defects (enamel exposed)
2 Obvious crevice at margin, dentin or base exposed
3 Debonded from one end
4 Debonded from both ends
Color match 0 Very good color match
1 Good color match
2 Slight mismatch in color or shade
3 Obvious mismatch, outside the normal range
4 Gross mismatch
Marginal discoloration 0 No discoloration evident
1 Slight staining, can be polished away
2 Obvious staining, cannot be polished away
3 Gross staining
Surface roughness 0 Smooth surface
1 Slightly rough or pitted
2 Rough, cannot be refinished
3 Surface deeply pitted, irregular grooves
Fracture of restoration 0 No fracture
1 Minor crack lines or tiny chipping (<1/4 of restoration)
2 Partial fracture of restoration (>1/4 of restoration)
3 Debonding of restoration
Fracture of tooth 0 No fracture of tooth
1 Minor crack lines in tooth
2 Partial fracture of tooth (>1/4 of crown)
3 Crown-root fracture (extraction)
Wear of restoration 0 No wear
1 Wear of restoration
Wear of antagonist 0 No wear
1 Wear of antagonist
Caries 0 No evidence of caries along the margin of the restoration
1 Caries evident continuous with the margin of the restoration
Post-operative sensitivity 0 No symptoms
1 Slight sensitivity
2 Moderate sensitivity
3 Severe pain

The data collection and the statistical analysis were performed using SPSS for Windows 23.0 (SPSS, Chicago, IL, USA). The frequency distributions of the evaluated criteria and the reasons for failure were described by descriptive statistics. Qualitative analysis based on the modified USPHS criteria was analyzed independently for each of the 12 evaluated clinical characteristics. Differences in the qualitative criteria between the materials were analyzed using Fisher’s Exact Test. Because of the cluster-effect related to the multiple restoration in some individual and its contextual variables the average event rates were modeled and compared with a “shared frailty” model. This model is an extension of the Cox proportional hazard model that includes a frailty term to take the contextual dependency of events within into account. Hazard ratios (HR) with respective 95% confidence intervals (CI) were determined.

Survival analysis was performed using the Kaplan–Meier statistical method to obtain the survival curves for the variables of interest, followed by Log-Rank test for comparison between groups. p values less than 5% were considered to be statistically significant in all applied tests.

Material and methods

Study design and participants

The database with clinical records from the Operative Dentistry Department at the University of Pécs was used in the present evaluation. From this database, all patients who had received direct RBC restoration in the maxillary anterior teeth by the first author (E.L.) for fracture or diastema closure (including peg-shaped lateral incisors) were selected for this retrospective analysis. The study protocol was approved by the Regional Research Ethics Committee of University of Pécs (3410.1./2009). All patients were contacted by phone or mail. Those patients who were able to participate in the study, signed a written, informed consent prior to the start of the clinical evaluation.

Inclusion and exclusion criteria

For this retrospective study, a total of 65 patients with ages ranging from 18 and 58 years old (25 males and 40 females, mean age: 25.2 at the time of restoration placement) were selected according to pre-determined inclusion criteria from the registers of a Hungarian clinical practice (University of Pécs), from June 2006 to December 2011, securing a minimum observation period of 5 years and the longest one of 10 years. The selected patients received a total of 163 direct RBC build-ups in their vital maxillary teeth. 70 central incisors and 22 lateral incisors were restored with the indication of fracture. Diastema closure was performed in 32 cases in central incisors, 31 cases in lateral incisors (including peg-shaped lateral incisors, n = 5) and 8 cases in canine. Information was given to each participants regarding the alternative treatment options. The inclusion criteria employed comprised of the following: all participants were at least 18 years old, able to read and sign the informed consent document, physically and psychologically able to tolerate the procedure. Furthermore, patients who were selected for the study had full dentition and normal occlusion without generalized periodontal disease, as verified by the clinical and radiographic records, and these patients had remained in continuous clinical follow-up, including at least 1 annual recall without attending other dentists. Reasons for placement of direct RBC build-ups were either fracture of the tooth or diastema, including peg-shaped lateral malformation correction as well or changing old restorations with the same dental history. Margins placed on enamel was a requirement, had to be fulfilled in order for the placement of direct RBC. Endodontically treated teeth at baseline were excluded from the study, however the necessity of endodontic treatment after build-up was recorded from the documentation during the evaluation. Dental history of the restorable tooth was recorded from the clinical documentation. The extension of the RBC restoration was grouped as following: <25%, 25–50% or >50% of the entire anatomical crown.

Restorative procedures

The brands, types, manufacturers, chemical compositions of the materials used in this study are listed in Table 1 .

Table 1
The brand, type, manufacturer, chemical composition of the materials used in this study.
Brand Type Manufacturer Chemical composition
Filtek Supreme XT Nanofill composite 3M ESPE, St Paul, MN, USA BisGMA, UDMA, TEGDMA, PEGDMA, 72.5 w% (55.6 v%) non-agglomerated/non-aggregated 20 nm silica and 4–11 nm zirconia filler, 0.6–20 μm aggregated cluster fillers
Enamel Plus HFO Micro-hybrid composite Micerium S.p.A., Avegno, Italy BisGMA, TEGDMA, UDMA, 1,4-butandiol-dimethacrylate, 75 w% (53 v%) 0.7 μm glass filler and highly dispersed 0.04 μm silicone dioxide
Adper Single Bond Total-etch adhesive 3M ESPE, St Paul, MN, USA BisGMA, UDMA, HEMA, glycerol 1,3-dimethacrylate, methacrylate functional copolymer of polyacrylic and polyitaconic acids, 10% 5 nm silane treated colloidal silica
Ultra-Etch Phosphoric acid Ultradent Products Inc, South Jordan, UT, USA 38% phosphoric acid
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Nov 22, 2017 | Posted by in Dental Materials | Comments Off on Direct resin composite restorations for fractured maxillary teeth and diastema closure: A 7 years retrospective evaluation of survival and influencing factors
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