Cytotoxicity effects and differentiation potential of ormocer-based and nanohybrid composite resins on human dental pulp stem cells.

OBJECTIVE: to compare conventional nanohybrid (Ceram.x Spectra) and ormocer-based (Admira fusion) dental composite resins effects on human dental pulp stem cells (hDPSCs) in terms of cytotoxicity, self-renewal, migration and osteogenic differentiation. METHODS: hDPSCs were cultured in presence of different dilutions (undiluted, form 1:2 to 1:100) of CeramX (CX) and Admira fusion (AD) eluates and viability assay in standard or osteogenic conditions were performed. Samples and eluates were prepared according to ISO 10993-12. In addition, apoptosis, self-renewal and migration activity evaluations were carried out. Osteogenic differentiation potential was tested by Alkaline Phosphatase Activity, alizarin red staining and gene expression of specific markers (ALP, RUNX2, OCN, OPN and COL1α1). Statistical analysis was performed by means of a One-way analysis of variance (One-way ANOVA) followed by a Tukey's test for multiple comparison; results were presented as mean ± standard error of mean (SEM). RESULTS: Admira Fusion demonstrated to be highly biocompatible and showed positive effects on hDPSCs proliferation and differentiation; on the contrary, conventional nanohybrid composite showed to be more cytotoxic and without any notable effect on stem cells differentiation. Moreover, the obtained results were further corroborated by a significant upregulation of osteogenic differentiation markers obtained in presence of ormocer-based composite resin eluate. Specifically, in AD 1:50 group expression levels of ALP, Runx2, Col1α1 were double than control (ALP, p = 0.045; Runx2, p = 0.003; Col1α1, p = 0.001) and CX 1:50 (ALP, p = 0.006; RUNX2, p = 0.029; Col1α1, p = 0.005). Moreover, in the same group, OPN and OCN resulted about 5 times more expressed as compared to control (OPN, p = 0.009; OCN, p = 0.0005) and CX 1:50 (OPN, p = 0.012; OCN, p = 0.0006). SIGNIFICANCE: The less cytotoxicity obtained by AD than conventional nanohybrid composite may be attributed to a reduced monomers release in the oral environment, supporting the hypothesis of limited adverse effect and enhanced healing potential, mainly when the material is positioned in close contact with pulp tissue.

Translational and transdisciplinary approach to the human papilloma virus - Preliminary evidence from the Italian "HPV board: a future without papilloma virus" project.

Human papillomavirus (HPV) is considered to be one of the viral infections associated with cancers and other diseases. HPV is detected asymptomatically in the oral mucosa. The presence of human papillomavirus in the oral mucosa appears to be closely associated with a series of benign and malign oral lesions. The aim of this paper is to report the Italian experience in applying translational protocols, using new technologies and multidisciplinary strategies in Human Papilloma virus detection and treatment. The "HPV board: a future without papilloma virus" project was born, promoted by CNEL (Italian Council of Economics and Labor) with the collaboration of numerous scientific societies to commonly approach to public knowledge of HPV-related oral lesions and their clinical management. The preliminary results are related to the assessment of the proof-of-concept of this new project. More in details, "HPV Board" is a project that plans the presence of a working group, made up of otolaryngologists, dentists, oral and maxillofacial surgeons, in close contact with gynecologists, oncologists and pediatricians; this working group manages to combine very transversal skills, in order to promote primary prevention projects, early diagnosis and adequate therapies. The "HPV BOARD" project will give the opportunity to increase the attention of patients and doctors on the early diagnosis of oncological diseases dependent on infection by the infectious agent HPV. In this panorama, dentists will have the role of "first sentinel" of public health because oral health is an indicator, too often overlooked, for the prevention of numerous diseases.

In vitro comparative study on the mechanical behavior of Zirconia and Polyetheretherketone in applied dental sciences.

OBJECTIVE: Recently, Zirconia and polyaryletherketone (PEEK) have attracted increasing interest as reliable and safe materials in dental applications, mainly because of their good biomechanical characteristics. The aim of this study was to investigate the response to different loads by prosthetic frameworks for supported fixed partial dentures (FPDs), thus simulating osseointegrated implants. MATERIALS AND METHODS: The specimens were divided into two groups (n= 5 each). Group A: FDPs in zirconia-ceramic; Group B: FDPs in PEEK-composite. These 2 groups were subjected to vertical loads so to evaluate structural deformation; then, they have been analyzed by scanning electron microscopy (SEM) at different magnifications. RESULTS: In tested samples, different types of mechanical failures have been observed. In Zirconia-specimens, chipping is the main failure noticed in this study, mostly in distal margins of the structure. Also, peek-specimens show failure and fracture. CONCLUSIONS: Zirconia and PEEK could be considered both good materials, but several investigations are needed to use these materials as an alternative to metals for fixed partial dentures.

Oral health status and Unmet Restorative Treatment Needs (UTN) in disadvantaged migrant and not migrant children in Italy.

AIM: Despite a global decline in caries experience in children, dental caries remains a common and persistent public health problem, being more prevalent among socioeconomically disadvantaged groups. The aim of this survey is to evaluate DMFT index, caries prevalence and Unmet Restorative Treatment Needs (UNT) index in migrant and not migrant children with low income, in Campania region (Italy), in order to plan and build up strategies for promoting dental health in children and adequate health care for vulnerable groups. MATERIALS AND METHODS: A sample of 553 children (age range: 12-14 years old) were recruited from volunteer patients at a charitable foundation in Naples (Italy) and were categorised into 2 subgroups, according to their status of "migrant" or "not migrant". Parents completed a questionnaire in order to investigate demographic and oral health behaviour. The participants were healthy and from low family income levels. DMFT scores and caries prevalence were calculated; UNT index was also calculated [D?(D + F)]%. The mean DMFT values related to the examined variables were calculated using one-way ANOVA. RESULTS: Mean DMFT and UTN index were 3.92±2.92 and 86.3% for migrants, and 3.29±3.21 and 68.4% for not migrants, respectively. The difference in the mean DMFT between the two groups was statistically significant (p=.027). Caries prevalence was 77.5% and 55.9% in the migrant group and in the not migrant group, respectively. High DMFT values were statistically associated to history of previous dental visit, sugar intake, brushing teeth once a day, and low mothers' educational level for both groups. CONCLUSION: Economically disadvantaged children showed high levels of dental caries. Furthermore, DMFT values, caries prevalence and unmet restorative treatment needs index among migrant children were higher than that of not migrant. In order to reduce inequalities in dental caries experience, there is a need to design policies aimed at primary prevention through health promotion programmes.

Calcium silicate/calcium phosphate biphasic cements for vital pulp therapy: chemical-physical properties and human pulp cells response.

OBJECTIVES: The aim was to test the properties of experimental calcium silicate/calcium phosphate biphasic cements with hydraulic properties designed for vital pulp therapy as direct pulp cap and pulpotomy. METHODS: CaSi-αTCP and CaSi-DCDP were tested for ion-releasing ability, solubility, water sorption, porosity, ability to nucleate calcium phosphates, and odontoblastic differentiation­alkaline phosphatase (ALP) and osteocalcin (OCN) upregulation­of primary human dental pulp cells (HDPCs). RESULTS: The materials showed high Ca and OH release, high open pore volume and apparent porosity, and a pronounced ability to nucleate calcium phosphates on their surface. HDPCs treated with CaSi-αTCP showed a strong upregulation of ALP and OCN genes, namely a tenfold increase for OCN and a threefold increase for ALP compared to the control cells. Conversely, CaSi-DCDP induced a pronounced OCN gene upregulation but had no effect on ALP gene regulation. CONCLUSIONS: Both cements showed high biointeractivity (release of Ca and OH ions) correlated with their marked ability to nucleate calcium phosphates. CaSi-αTCP cement proved to be a potent inducer of ALP and OCN genes as characteristic markers of mineralization processes normally poorly expressed by HDPCs. CLINICAL RELEVANCE: Calcium silicate/calcium phosphate cements appear to be attractive new materials for vital pulp therapy as they may provide odontogenic/dentinogenic chemical signals for pulp regeneration and healing, and dentin formation in regenerative endodontics.

Marginal Leakage of Class V Composite Restorations Assessed Using Microcomputed Tomography and Scanning Electron Microscope.

OBJECTIVE: The aim of the study was to compare in Class V composite restorations marginal leakage measurements obtained with microcomputed tomography (micro-CT) and scanning electron microscopy (SEM) observations. METHODS: Class V cavities were prepared on 10 human molars and restored using Optibond FL (Kerr, Orange, CA, USA) and Premise Flowable (Kerr). Sealing ability was evaluated by assessing silver-nitrate penetration depth along enamel and dentin margins. Leakage was quantified using a scoring system. Micro-CT analysis provided 502 cross-sectional images for each tooth. Microleakage evaluation was performed first on three cross-sections corresponding to the sections examined by SEM, then on all 502 of the obtained micro-CT images. SEM observations were performed first at 20× magnification, then, if showing a zero score, at 80× magnification. Enamel and dentin microleakage scores assigned to corresponding sections through micro-CT and SEM (20×) were compared (Wilcoxon signed-rank test, α=0.05). RESULTS: No statistically significant difference in leakage scores emerged between micro-CT and 20×-magnification SEM. Eight tooth sections that were given a zero score under SEM at 20× magnification showed to be infiltrated at the higher magnification (80×). For five teeth a higher score was assigned following scanning of 502 cross-sections than based on the observation of three sections. CONCLUSIONS: Micro-CT presents as a valid, nondestructive in vitro method to quantitatively evaluate marginal leakage of adhesive restorations.

The treatment of the large periradicular endodontic injury.

AIM: Periradicular lesions of endodontic origin are characterized by polymicrobial infections, part of which appear to play a crucial role in the facultative anaerobic bacterical species. In literature there is a strong disagreement about the choice of treatment in large periradicular lesions of endodontic origin: some authors propose the orthograde root canal therapy, others surgical therapy with apicectomia, retrograde filling of the cavity and review instrument. The purpose of this study was to demonstrate the effectiveness of orthograde endodontic treatment in case of periapical lesions of endodontic origin of dimensions larger than 20 mm. METHODS: It was evaluated a sample of 60 cases, ages between 18 and 70 years, 32 men and 28 women. The cases have been treated by orthograde endodontic. Were included mono and pluriradicular teeth with periapical lesion of endodontic origin primary or secondary at endodontic incongruous treatment, with dimensions larger than 20 mm. The sample was divided into Group A: 19 cases in which was possible to complete the root canal therapy in the same event; Group B: 41 cases in which there was drainage. Dressing was applied with pure calcium hydroxide, which was renewed every 10 days for a maximum of 30, was eventually completed the endodontic therapy. RESULTS: Group A: 13 out of 19 cases showed healing at 5 years. Of the remaining 6, there were three failures, a crown-root fracture, missed two follow-up. At 10 years of the 13 successes, 2 cases showed relapse. Group B: 41 cases, later reduced to 30 we had 19 successes in 5 years. Of the remaining 11: 3 crown-root fractures, 2 missed the follow-up, 6 failures. At 10 years of the 19 successes, two were lost because of fracture, one for a relapse. Discussion. The results show the importance of drainage, which can affect the apical seal and therefore the success of endodontic therapy, but allows decompression of the periradicular lesion and symptoms regression. The use of calcium hydroxide in the intermediary dressings allows the neutralization of acidic compounds, alkaline phosphatase activation creating a significant development of the antibacterial action. Proper instrumentation and cleansing of root canals allows the reduction of over one thousand times the bacterial load. The coronal seal has, through the adhesive techniques of restorative materials, a crucial role in closing the doors of entry the bacterial contamination of treated root canals. CONCLUSION: The endodontic therapy by orthograde is considered primary therapeutic choice in case of large endodontic lesions, given the success at rate both 5 (Group A 68,41%, Group B 63,33%) and 10 years (Group A 57.88%, Group B 53.32%).

Effects of sodium hypochlorite and ethylenediaminetetraacetic acid on rotary nickel-titanium instruments evaluated using atomic force microscopy.

AIM: To use atomic force microscopy (AFM) to evaluate the effects of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) on the surface characteristics of ProTaper rotary nickel-titanium instruments. METHODOLOGY: A total of twenty ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) instruments (S1, S2, F1, F2) were divided into five groups: no immersion, immersion in 5.25% NaOCl for 5 or 10min and immersion in 17% EDTA for 5 or 10min. Twenty surface areas along 3-mm sections at the tip of the files (perfect squares of 1x1µm) were analysed by AFM operating in contact mode under ambient conditions. Three-dimensional images (400x400 lines) were processed using Gwyddion software, and the roughness average (Ra) and the root mean square value (RMS) of the scanned surface profiles were recorded. Data were analysed by means of anova and paired samples t-test. RESULTS: Three-dimensional AFM images of the surface of ProTaper instruments, including new and those immersed in NaOCl and EDTA solutions, revealed topographic irregularities at the nanometric scale. RMS and Ra values of instruments treated with NaOCl and EDTA solutions were statistically higher than that of the new ones (P<0.05). CONCLUSIONS: Atomic force microscopy three-dimensional images and roughness values indicated that short-term contact between NaOCl and EDTA endodontic irrigants and ProTaper instruments caused alterations in the surface of instruments.

Fast curing of restorative materials through the soft light energy release.

OBJECTIVE: The effect of a novel light curing process, namely soft light energy release (SLER), on shrinkage, mechanical strength and residual stress of four dental restorative materials (DEI experience, Gradia Direct, Enamel Plus HFO and Venus) was investigated. METHODS: Composite specimens were fast cured through high level of power density and soft light energy release. Temperature, linear shrinkage and light power measurements were acquired in parallel in order to assess the effect of light modulation on temperature and shrinkage profiles during the light curing process and the following dark reaction phase. The small punch test and Raman spectroscopy were adopted to investigate the effect of SLER on mechanical strength and on internal stress, respectively. RESULTS: The soft light energy release photo-polymerization allows to reduce of about 20% the shrinkage rate and to increase the strength of fast light cured specimens. In addition, a more relaxed and homogeneous internal stress distribution was observed. SIGNIFICANCE: Properties of fast cured restorative materials can be improved by adopting the soft light energy release process.

NF-kappaB protection against apoptosis induced by HEMA.

The cytotoxicity of dental monomers has been widely investigated, but the underlying mechanisms have not been elucidated. We studied the molecular mechanisms involved in cell death induced by HEMA. In human primary fibroblasts, HEMA induced a dose-dependent apoptosis that was confirmed by the activation of caspases-8, -9, and -3. We found an increase of reactive oxygen species (ROS) and NF-kappaB activation after HEMA exposure. Blocking of ROS production by anti-oxidants had no direct influence on apoptosis caused by HEMA, but inhibition of NF-kappaB increased the fraction of apoptotic cells. Accordingly, mouse embryonic fibroblasts (MEF) from p65-/- mice were more susceptible to HEMA-induced apoptosis than were wild-type controls. Our results indicate that exposure to HEMA triggers apoptosis and that this mechanism is not directly dependent upon redox signaling. Nevertheless, ROS induction by HEMA activates NF-kappaB, which exerts a protective role in counteracting apoptosis.

Inhibition of phosphatidylinositol 3-kinase amplifies TEGDMA-induced apoptosis in primary human pulp cells.

Cytotoxicity of triethylene glycol dimethacrylate (TEGDMA), a co-monomer of dental resinous restorative materials, is firmly established in vitro, but the molecular mechanisms are unknown. Here we examined apoptosis and necrosis induced by TEGDMA in human primary pulp cells. The levels of apoptotic and necrotic cell populations differentially increased after exposure to increasing concentrations of TEGDMA. A two-fold increase in the percentage of apoptotic cells was induced by 1 mmol/L TEGDMA. However, a population shift among cells in apoptosis and necrosis was detected when cell cultures were exposed to 2 mmol/L TEGDMA. Inhibition of the MAP Kinase/ERK pathway had no influence on cell survival, but inhibition of phosphatidylinositol 3 kinase (PI3-Kinase; Akt/protein kinase B) by LY294002 amplified TEGDMA-induced apoptosis. Moreover, Akt phosphorylation was inhibited in the presence of TEGDMA. These results suggest that depression of PI3K signaling may be a primary target in TEGDMA-induced apoptosis.

Evaluation of leakage of bacteria and endotoxins in teeth treated endodontically by two different techniques.

Root canal recontamination occurs after contact between oral-bacterial flora and the coronal extremity of the root canal. The aim of this study was to evaluate the time required for endotoxins and bacteria to penetrate through root-canal obturations performed with vertical and lateral gutta-percha condensation techniques. Specimens prepared by the two alternative methods were exposed to contaminated saliva, and leakage into the root was evaluated over time. None of the obturated roots was infiltrated by endotoxins after 31 days. On the contrary, between day 13 and day 37 bacteria had infiltrated all specimens.

3D-finite element analyses of cusp movements in a human upper premolar, restored with adhesive resin-based composites.

The combination of diverse materials and complex geometry makes stress distribution analysis in teeth very complicated. Simulation in a computerized model might enable a study of the simultaneous interaction of the many variables. A 3D solid model of a human maxillary premolar was prepared and exported into a 3D-finite element model (FEM). Additionally, a generic class II MOD cavity preparation and restoration was simulated in the FEM model by a proper choice of the mesh volumes. A validation procedure of the FEM model was executed based on a comparison of theoretical calculations and experimental data. Different rigidities were assigned to the adhesive system and restorative materials. Two different stress conditions were simulated: (a) stresses arising from the polymerization shrinkage and (b) stresses resulting from shrinkage stress in combination with vertical occlusal loading. Three different cases were analyzed: a sound tooth, a tooth with a class II MOD cavity, adhesively restored with a high (25 GPa) and one with a low (12.5GPa) elastic modulus composite. The cusp movements induced by polymerization stress and (over)-functional occlusal loading were evaluated. While cusp displacement was higher for the more rigid composites due to the pre-stressing from polymerization shrinkage, cusp movements turned out to be lower for the more flexible composites in case the restored tooth which was stressed by the occlusal loading. This preliminary study by 3D FEA on adhesively restored teeth with a class II MOD cavity indicated that Young's modulus values of the restorative materials play an essential role in the success of the restoration. Premature failure due to stresses arising from polymerization shrinkage and occlusal loading can be prevented by proper selection and combination of materials.

Mechanical strength of tooth fragment reattachment.

The aim of this study was static and fatigue test investigation of the strength of a tooth fragment reattached with adhesives to the tooth body. Central bovine incisor teeth were used, and standardized fragments were obtained by cutting the incisal edge of the selected teeth. All the fragments were reattached using a multistep dentine adhesive system, and the specimens were randomly divided into two groups (A and B). Group B specimens underwent a further dental treatment: a circumferential double chamfer prepared around the external cut interface was filled with light cured composite restorative resin. Static and fatigue bending tests were performed and linear elastic equations were used to analyze and compare the strength of the treated teeth. The results indicated that the static and fatigue bending properties were improved by using reinforcement with composite restorative resin.

[Mouth opening in patients with systemic sclerosis: base analysis and during follow-up]. / L'apertura della bocca in pazienti con sclerosi sistemica: analisi basale e in corso di follow-up.

BACKGROUND: A large number of orofacial abnormalities have been described in patients with Systemic Sclerosis (SSc) but no data are reported on the correlation with different subgroups of patients on the efficacy of different therapies. METHODS: In the present study mouth opening was retrospectively evaluated in 40 patients with SSc in whom measurement of interlabial distance was taken at the first clinical control and during follow-up. The data confirmed that the mouth opening is significantly decreased in patients with SSc independently from sclerosis subgroup, age or disease duration. RESULTS: Follow-up (8 +/- 8.3 years) showed a different behaviour of the parameter: in 12 patients (group I) no variation in mouth opening was detected, in 18 patients (group II) a decrease and in 10 patients (group III) an increase was observed. CONCLUSIONS: The only difference between the three groups was the treatment received: 80% of the patients of group III (p < 0.01) have been treated with cyclophosphamide (CF). Our data further support the efficacy of treatment with CF in patients with SSc.

Carbon fiber post adhesion to resin luting cement in the restoration of endodontically treated teeth.

Carbon fiber posts (CFP) are widely used in the restoration of endodontically treated teeth to enhance the mechanical behavior in spite of metallic posts and to prevent vertical fractures of the tooth under chewing loads. The post is cemented inside the canal lumen using polymer resins with Young's modulus lower than dentine. In this conditions the stress concentration is located at the post-cement interface and in the cement bulk itself, preserving radicular dentine from dangerous stress accumulation. The mechanical resistance of CFP posts cemented in human dentine was evaluated by the means of mechanical pull-out tests assisted by the finite element analysis. The average bond strength and the critical stress values of the CHP-cement interface were 25 MPa and 50 MPa respectively.

Debonding of adhesively restored deep Class II MOD restorations after functional loading.

PURPOSE: To assess debonding due to functional loading at the cervical dentin margins of deep Class II MOD restorations prepared with a variety of adhesive restoratives in endodontically-treated teeth. MATERIALS AND METHODS: MOD preparations and endodontic treatment were carried out on extracted sound maxillary premolars. The cavities were restored with seven material combinations: Three different resin-based composites (RBC) (Z100, Herculite XRV or Clearfil RP with their respective bonding systems); two bonded amalgam combinations (Valiant with Superbond D or with Panavia 21) and two sandwich combinations [the RBC Tetric with the polyacid-modified RBC (compomer) Compoglass or Z100 with the resin-modified glass ionomer Fuji II LC]. For each group, half of the samples were exposed to mechanical functional loading and the other half served as control. Imperfect bond formation and debonding due to loading was determined by dye penetration. In addition, the dye penetration scores were correlated with the cusp fracture strengths of similarly prepared restorations of a previous study. RESULTS: After functional loading, the RBC in combination with hybridizing dentin bonding agents showed better preservation of marginal integrity than the sandwich restorations, which in turn performed better than the amalgam restorations (P < 0.05). Debonding correlated with reduction in fracture resistance. Under the conditions of this study, debonding of adhesive MOD restorations by functional loading can best be prevented by using RBC in combination with hybridizing dentin-bonding systems.

A comparison of nimesulide beta cyclodextrin and nimesulide in postoperative dental pain.

The aim of this study was to assess the efficacy and tolerability of single doses of nimesulide beta cyclodextrin compared with nimesulide in patients with dental pain following surgical procedures. This was a randomised, double-blind, between-patient, multicentre study involving 148 outpatients suffering from moderate to severe pain, who received single doses of either 400 mg nimesulide beta cyclodextrin or 100 mg nimesulide. The principal criterion for efficacy was pain intensity assessed on a visual analogue scale (VAS) 15 minutes after drug intake. Pain intensity was further evaluated 30, 45, 90, 120, 180, 240 and 360 minutes after dosing. Pain relief was evaluated at the same time points by means of a categorical scale. The time point of first pain relief, the use of rescue medication and the global evaluation of efficacy were also recorded. The reduction in pain intensity was significantly more pronounced in the nimesulide beta cyclodextrin group at 15, 30, 45 and 60 minutes (p < 0.01). Pain relief was significantly greater (p < 0.05) and more rapid with nimesulide beta cyclodextrin. In the patient overall assessment of efficacy, nimesulide beta cyclodextrin and nimesulide were rated excellent or good by 95% and 92% respectively; only one patient in the nimesulide beta cyclodextrin group needed rescue medication. Both study drugs were effective and well tolerated in the treatment of acute dental pain, with nimesulide beta cyclodextrin showing a faster onset of analgesic action.

Inhibition by glass-ionomer cements of protein synthesis by human gingival fibroblasts in continuous culture.

The effects of several glass-ionomer cements (Baseline and Chem Fil of De Trey; Ketac Fil and Ketac Bond of ESPE; Vitrebond and Vitremer of 3 M) on the protein synthesis of cultured gingival fibroblasts were studied. The presence of cements in the culture medium inhibited protein synthesis, although the relative effectiveness varied significantly. The cements tested have been ranked in three groups, group A (Chem Fil and Ketac Fil), group B (Ketac Bond and Baseline) and group C (Vitrebond and Vitremer), showing 50, 75 and 100% reduction in protein synthesis, respectively. Incubation of cells with medium previously conditioned by Baseline and Ketac Fil caused only transient inhibition of protein synthesis followed by almost complete recovery. This recovery was not observed when the medium was conditioned with Vitrebond. A characterization of the factors determining the inhibitory effect of one cement in each group was attempted. The cements, irrespective of the type, produced small but reproducible decreases in the pH of the medium but released fluoride ions to a different extent. Both changes in the pH of the medium and in the fluoride concentration inhibited protein synthesis by cultured gingival fibroblasts. The different action of cements can be explained, at least in part, by a differing release of fluoride ions.

Fracture resistance of endodontically-treated premolars adhesively restored.

PURPOSE: To investigate the cusp fracture resistance of endodontically treated teeth, adhesively restored with various materials. MATERIALS AND METHODS: MOD preparations and endodontic treatment was carried out on extracted sound maxillary premolars. The cavities were restored with the amalgam Valiant in combination with Superbond or Panavia bonding, the resin composites Z100, Herculite XRV or Clearfil RP with their respective bonding systems, Z100 in combination with the glass ionomers Ketac Fil, Fuji II and Vitremer, and Tetric in combination with Compoglass. Fracture resistance was measured by axial loading in an Instron testing machine. RESULTS: One of the restorative methods, resin composites in combination with dentin bonding systems in beveled MOD preparations rendered the tooth a cusp fracture resistance which did not differ significantly from that of sound natural teeth. Two other restorative methods, bonded amalgam and a sandwich of glass ionomer cement/resin composite in beveled preparations were significantly weaker in resisting cusp fracture than sound natural teeth, but still significantly stronger than the unrestored tooth with a MOD preparation. It was statistically apparent that several adhesive restorative systems could satisfactorily be used to restore teeth after endodontic therapy.