Evaluation of Temperature and Stress Distribution on 2 Different Post Systems Using 3-Dimensional Finite Element Analysis.

BACKGROUND The mouth is exposed to thermal irritation from hot and cold food and drinks. Thermal changes in the oral cavity produce expansions and contractions in tooth structures and restorative materials. The aim of this study was to investigate the effect of temperature and stress distribution on 2 different post systems using the 3-dimensional (3D) finite element method. MATERIAL AND METHODS The 3D finite element model shows a labio-lingual cross-sectional view of the endodontically treated upper right central incisor and supporting periodontal ligament with bone structures. Stainless steel and glass fiber post systems with different physical and thermal properties were modelled in the tooth restored with composite core and ceramic crown. We placed 100 N static vertical occlusal loading onto the center of the incisal surface of the tooth. Thermal loads of 0°C and 65°C were applied on the model for 5 s. Temperature and thermal stresses were determined on the labio-lingual section of the model at 6 different points. RESULTS The distribution of stress, including thermal stress values, was calculated using 3D finite element analysis. The stainless steel post system produced more temperature and thermal stresses on the restorative materials, tooth structures, and posts than did the glass fiber reinforced composite posts. CONCLUSIONS Thermal changes generated stresses in the restorative materials, tooth, and supporting structures.

Comparison of apical microleakage of dual-curing resin cements with fluid-filtration and dye extraction techniques.

BACKGROUND: Endodontically treated teeth with excessive loss of tooth structure are frequently restored using fiber posts. In this in vitro study, the apical leakage of self- and dual-activated curing modes for dual-curing resins cementing a translucent fiber post was evaluated using computerized fluid filtration meter and dye extraction method. MATERIAL AND METHODS: One hundred and four extracted human maxillary incisors with single root and canal were used. Experimental samples embedded in a closed system were divided into 4 groups (n=20) according to 2 dual-curing luting systems, with 2 different curing modes (either with self- or light-activation): (1) Panavia F 2.0 with self-cure, (2) Panavia F 2.0 with light-activation, (3) Clearfill SA with self-cure, and (4) Clearfill SA with light activation. Twenty-four teeth served as negative and positive controls. Translucent fiber posts were luted in the roots except in the control groups. RESULTS: Statistical analysis indicated no significant difference in leakage among groups (p>0.05) with 4.12 × 10(-4) (Panavia self-cure), 4.55 × 10(-4) (Clearfill SA self-cure), 5.17 × 10(-4) (Panavia dual-cure), and 5.59 × 10(-4) (Clearfill SA dual-cure) in fluid-filtration method. Absorbance values for dye-extraction method were 266 nanometer (nm) (Panavia self-cure), 268 nm (Clearfill SA self-cure), 270 nm (Panavia dual-cure), and 271 nm (Clearfill SA dual-cure), in which difference among the groups were not statistically significant (p>0.05). When comparing the leakage, assessment methods results showed no statistically significant difference between the tested evaluation techniques (p>0.05). CONCLUSIONS: Light- and self-activation curing modes of Panavia F 2.0 and Clearfill SA perform similar to each other in a closed system.

Efficacy of Two Irrigants Used with Self-Adjusting File System on Smear Layer: A Scanning Electron Microscopy Study.

Mechanical instrumentation of root canals produces a smear layer that adversely affects the root canal seal. The aim of this study was to evaluate efficacy of MTAD and citric acid solutions used with self-adjusting file (SAF) system on smear layer. Twenty-three single-rooted human teeth were used for the study. Canals were instrumented manually up to a number 20 K file size. SAF was used to prepare the root canals. The following groups were studied: Group 1: MTAD + 5.25% NaOCl, Group 2: 20% citric acid + 5.25% NaOCl, and Group 3: Control (5.25% NaOCl). All roots were split longitudinally and subjected to scanning electron microscopy. The presence of smear layer in the coronal, middle, and apical thirds was evaluated using a five-score evaluation system. Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis. In the coronal third, Group 2 exhibited the best results and was statistically different froms the other groups (P < 0.05). There was not a significant difference among the three thirds of groups according to in-group comparisons (P > 0.05). The solutions used in Group 1 and 2 could effectively remove smear layer in most of the specimens. However, citric acid was more effective than MTAD in the three thirds of the canal.

Patient-specific factors in the proximity of the inferioralveolar nerve to the tooth apex

Objectives: To evaluate whether age and gender differences are predictive factors for inferior alveolar nerve position with respect to mandibular first molar roots. Study Design: Cone-beam computed tomography scans [0.2-mm3 voxel size; n = 200 (100 males, 100 females)] of patients aged 15-65 years showing mandibular first and second molars were included in this study. Patients with pathoses that might affect inferior alveolar nerve position, including second molar and/or first premolar extraction, were excluded. Fourteen measurements (mm) were taken from the inferior alveolar nerve to the mesial and distal root apices. Subjects were grouped by age and gender. Data were analysed using two-way analyses of variance with post hoc Bonferroni corrections.Results: The distance from the inferior alveolar nerve to the root apices was smaller in females than males, regardless of age (p < 0.01). Distal roots were closer to the nerve than mesial roots in both genders (p < 0.05). Total buccolingual mandibular length (at 3-mm apical level) was shorter in females than males (p < 0.01) but mean buccolingual mandibular width at the level of the inferior alveolar canal did not differ. Nerve-root apex distances were significantly shorter in males and females aged 16-25 and 56-65 years than in other age groups (p < 0.01).Conclusions: The distance between inferior alveolar nerve and mandibular first molar roots depends upon the age and gender: it is shorter in females than in males and in subjects aged 16-25 years and >55 years than in other age groups (AU)

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Self-adjusting files in retreatment: a high-resolution micro-computed tomography study.

INTRODUCTION: Rotary instruments that are used for retreatment are very effective, but most of them leave root filling residue in the canal. The aim of this study was to evaluate the efficacy of removing gutta-percha-based root fillings with ProTaper retreatment files (Dentsply Maillefer, Ballaigues, Switzerland) followed by F1 and F2 ProTaper instruments and to compare these results with those obtained with a #25 .06 ProFile instrument (Dentsply Maillefer) followed by the Self- Adjusting File (SAF; ReDent, Ra'anana, Israel) using high resolution micro-computed tomography (CT) scanning. METHODS: Twenty-eight mandibular molar teeth with oval distal root canals were divided into 2 equal groups of 14 teeth each. The distal root canals were instrumented with ProTaper files up to an F2 instrument, the roots were subsequently filled, and the root filling was allowed to set fully. Removal of the root canal filling was performed with D1-D3 ProTaper retreatment files followed by F1 and F2 ProTaper instruments or with a #25 .06 ProFile followed by SAFs. Chloroform was used in both groups to assist in the removal of the root filling material. High-resolution micro-CT scans were used to measure the residual quantities of the root filling material after completion of the procedures. Statistical analysis was performed using the Wilcoxon test and the Student t test. RESULTS: The median root filling residue in the ProTaper group was 5.39% (interquartile range [IQR] = 4.71) of the original volume of the root canal filling. In the ProFile and SAF group, the median residue was 0.41% (IQR = 1.64, P < .001). An arbitrarily selected threshold of less than 0.5% residue was defined as "effectively cleaned," and 57% of the teeth treated with the ProFile and the SAF met this threshold, whereas none of the cases in the ProTaper group did. The ProFile and SAF procedure required less time than the ProTaper protocol. CONCLUSIONS: None of the retreatment methods rendered all of the canals completely free of all root filling residue. Under the conditions of this study, the ProFile and SAF procedure was more effective than the ProTaper procedure and left significantly less root filling residue in the root canal.

Patient-specific factors in the proximity of the inferior alveolar nerve to the tooth apex.

OBJECTIVES: To evaluate whether age and gender differences are predictive factors for inferior alveolar nerve position with respect to mandibular first molar roots. STUDY DESIGN: Cone-beam computed tomography scans [0.2-mm3 voxel size; n = 200 (100 males, 100 females)] of patients aged 15-65 years showing mandibular first and second molars were included in this study. Patients with pathoses that might affect inferior alveolar nerve position, including second molar and/or first premolar extraction, were excluded. Fourteen measurements (mm) were taken from the inferior alveolar nerve to the mesial and distal root apices. Subjects were grouped by age and gender. Data were analysed using two-way analyses of variance with post hoc Bonferroni corrections. RESULTS: The distance from the inferior alveolar nerve to the root apices was smaller in females than males, regardless of age (p < 0.01). Distal roots were closer to the nerve than mesial roots in both genders (p < 0.05). Total buccolingual mandibular length (at 3-mm apical level) was shorter in females than males (p < 0.01) but mean buccolingual mandibular width at the level of the inferior alveolar canal did not differ. Nerve-root apex distances were significantly shorter in males and females aged 16-25 and 56-65 years than in other age groups (p < 0.01). CONCLUSIONS: The distance between inferior alveolar nerve and mandibular first molar roots depends upon the age and gender: it is shorter in females than in males and in subjects aged 16-25 years and >55 years than in other age groups.

Measuring bone density in healing periapical lesions by using cone beam computed tomography: a clinical investigation.

INTRODUCTION: Differences in bone density before and after endodontic treatment were examined in teeth with periapical lesions in Hounsfield units (HUs) by using cone beam computed tomography (CBCT). METHODS: Sixteen patients requiring endodontic treatment for periapical lesions underwent CBCT scan before and after treatment. Their bone densities were calculated in HUs. The study included 16 lesions measuring 8-10 mm in diameter. HU measurements were taken from an area of 2.25 mm(2) on the CBCT images where the bone density was lowest, before and after treatment. RESULTS: The initial and final measurements were compared statistically by using paired samples statistics at the 5% significance level. CONCLUSIONS: The results of this study support the use of CBCT to measure bone density before and after endodontic treatment.

Effectiveness of ethylenediaminetetraacetic acid (EDTA) and MTAD on debris and smear layer removal using a self-adjusting file.

OBJECTIVE: The aim of this study was to investigate the cleaning ability of a self-adjusting file (SAF) system regarding debris and smear layer removal using ethylenediaminetetraacetic acid (EDTA) or MTAD. STUDY DESIGN: In total, 45 maxillary incisor teeth were randomly divided into 2 different irrigation groups of 20 canals each and a negative control group of 5 canals. The canals in each of the irrigation groups were irrigated using sodium hypochlorite (1.3%) as an initial irrigant during the first 2 minutes of operation, followed by 2 minutes continuous irrigation with either 17% EDTA or MTAD in a closed system. The negative control group was irrigated using 1.3% sodium hypochlorite. The roots were split longitudinally and subjected to scanning electron microscopy (SEM). The presence of debris and smear layer in the coronal, middle, and apical thirds of the canal was evaluated using a 5-grade scoring system with ×200 and ×2,000 magnification, respectively. RESULTS: The SAF operation with 2-minute continuous irrigation using MTAD resulted in root canal walls that were free of smear layer in 85%, 70%, and 60% and of debris in 95%, 90%, and 95% of the coronal, middle, and apical thirds of the root canals, respectively. The SAF operation with continuous irrigation using EDTA resulted in root canal walls that were free of smear layer in 85%, 60%, and 50% and of debris in 95%, 90%, and 85% of the coronal, middle, and apical thirds of the root canals, respectively. Teeth in the negative control group were totally covered with debris. Evaluation by SEM showed no significant difference between the tested irrigants in removing the smear layer and debris among the different regions of the root canal. Both groups were significantly different from the negative control group. CONCLUSIONS: When using the SAF, the protocols used in this study were effective for debridement for all regions of the root canal even for the apical thirds.

Evaluation of radicular dentin erosion and smear layer removal capacity of Self-Adjusting File using different concentrations of sodium hypochlorite as an initial irrigant.

OBJECTIVE: The aim of this study was to evaluate Self-Adjusting File (SAF) in the removal of smear layer and impact on the dentin surface using sodium hypochlorite (NaOCl) as an initial irrigation solution at 3 different concentrations combined with 1% EDTA. In addition, the erosive effect of this dual irrigation regime was examined. STUDY DESIGN: Root canal preparations were performed in 30 teeth using the SAF with a continuous irrigation device (Vatea) in a closed system in which the apical foramen was sealed. The vibration mode was on for 5 minutes during the preparation. Three different concentrations of NaOCl (1.3%, 2.6%, and 5.25%) and 1% EDTA were used for continuous irrigation. The final flush was also performed using NaOCl with the vibration mode on. The roots were split longitudinally and subjected to scanning electron microscopy (SEM). The presence of the smear layer was scored using a 5-point scoring system, and the erosive capacity of the irrigants were scored using a 3-point scoring system. RESULTS: The results showed no significant difference in smear layer removal among different concentrations of NaOCl and among the regions. Clean dentin surfaces were observed in 80%, 70%, and 70% with a score of 1 or 2 of the apical thirds using 1.3%, 2.6%, and 5.25% NaOCl, respectively. The 1.3% and 2.6% NaOCl solutions showed similar erosion patterns on the root canal walls (P > .05); however, 5.25% NaOCl caused severe erosion (P < .05). CONCLUSIONS: When using the SAF with continuous irrigation and vibration, lower concentrations of NaOCl and EDTA can be recommended for efficient clinical removal of the smear layer even in the apical thirds and to avoid excessive erosion of root dentin.

Cone-beam dental computerize tomography for evaluating changes of agingin the dimensions central superior incisor root canals

Objectives: Cone-beam dental computerize tomography (CBCT), a noninvasive imaging method, was used to imagethe pulp-dentin complex. Pulp changes histologically with aging. While many studies have investigated thehistological changes in pulp, few studies have focused on the changes in the shape of the root canals. This studyevaluated the changes in the root canals with aging of central superior teeth using CBCT.Study Design: The study examined 100 non-carious maxillary central teeth. These teeth were divided into five groupsaccording to the age of the patients: Group A:15‑24, Group B: 25‑34, Group C: 35‑44, Group D: 45‑54 and Group E: 55years and older. CBCT was used to determine root length, and pulp width at the cervical, apical 1/2, and apical 1/3.Results: On comparing the groups using one-way analysis of variance (ANOVA), the root length did not differ (P >0.05), while the pulp width at the cervical, apical 1/2, and apical 1/3 differed between the groups (P < 0.001).Conclusions: The pulp length did not change with aging, while the pulp width did change. CBCT can be used todetermine the precise root length and width, to prevent iatrogenic exposure of the apex, complementing existingmethods. This will improve the prediction of the prognosis of root canal treatment (AU)

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Influence of fiber-reinforced composites on the resistance to fracture of vertically fractured and reattached fragments.

INTRODUCTION: The aim of this in vitro study was to evaluate the fracture type and test the effects of 2 different fibers on fracture strength of roots with reattached fragments. The null hypothesis was that adding suitable fibers to the content of dual-cure adhesive resin cement increases the fracture resistance of reattached fragments under vertical forces. METHODS: Root canals of 45 teeth were prepared, and the teeth were intentionally fractured into 2 separate fragments. Control groups (n = 7 each) consisted of unfractured teeth with instrumented and obturated or only instrumented root canals. The fractured teeth were divided into 3 groups (n = 15 each), and separated fragments were reattached by using (1) dual-cured resin cement (Clearfil SA), (2) dual-cured resin cement + polyethylene fiber (Construct), or (3) dual-cured resin cement + glass fiber (Stick-Net). Force was applied at a constant speed of 0.5 mm/min to the root until fracture. Mean load was recorded and analyzed statistically by using Kruskal-Wallis and Dunn tests (P = .05). Fracture types were analyzed by using χ(2) analysis with Yates correction. RESULTS: Stick-Net demonstrated the lowest fracture resistance (P < .05), whereas Construct and Clearfil SA had similar fracture strengths (P > .05). The roots in the control group showed the highest fracture resistance. However, there was no statistically significant difference between the Construct, Clearfil SA, and control groups (P > .05). CONCLUSIONS: Separated fragments of vertically fractured teeth can be reattached by using a dual-cured resin or by adding polyethylene fiber (Construct).

Cone-beam dental computerized tomography for evaluating changes of aging in the dimensions central superior incisor root canals.

OBJECTIVES: Cone-beam dental computerize tomography (CBCT), a noninvasive imaging method, was used to image the pulp-dentin complex. Pulp changes histologically with aging. While many studies have investigated the histological changes in pulp, few studies have focused on the changes in the shape of the root canals. This study evaluated the changes in the root canals with aging of central superior teeth using CBCT. STUDY DESIGN: The study examined 100 non-carious maxillary central teeth. These teeth were divided into five groups according to the age of the patients: Group A:15-24, Group B: 25-34, Group C: 35-44, Group D: 45-54 and Group E: 55 years and older. CBCT was used to determine root length, and pulp width at the cervical, apical 1/2, and apical 1/3. RESULTS: On comparing the groups using one-way analysis of variance (ANOVA), the root length did not differ (P>0.05), while the pulp width at the cervical, apical 1/2, and apical 1/3 differed between the groups (P<0.001). CONCLUSIONS: The pulp length did not change with aging, while the pulp width did change. CBCT can be used to determine the precise root length and width, to prevent iatrogenic exposure of the apex, complementing existing methods. This will improve the prediction of the prognosis of root canal treatment.

Evaluation of ectodermal dysplasia.

This case series report outlines possible cranio-maxillofacial deformation consequences associated with ectodermal dysplasia (ED) and embryonic malformations, including dental agenesis. Also described are the oral aspects and rehabilitation. A total of 14 ED patients (7 males and 7 females, aged 5-45 years) underwent clinical examination before assessment and treatment. Lateral cephalometric radiography, Steiner's analysis, and respiratory capacity tests were performed. Most of the patients had sparse or absent hair, a short face with an unusual facial concavity, a maxillary retrusion, and a relative mandible protrusion. Depending on age and orthopedic abnormalities, patients were treated with prosthodontic and orthodontic approaches or implant treatment. Therapists should take a comprehensive and multidisciplinary approach with these patients to improve their dental, masticatory, growth, and orthognathic conditions, as well as esthetic appearance.

A new method: measurement of microleakage volume using human, dog and bovine permanent teeth

This study investigates the feasibility of a different new approach to determining the microleakage volume associated with dental restorations (Class V cavity restorated with glass ionomer cement + high copper amalgam) and the relative marginal adaptation deficiency of dog, bovine and human permanent teeth in in vitro conditions. Also researched is the appropriateness of using dog and bovine teeth in in vitro studies rather than human teeth. Our method utilizes the molecular adsorption characteristics of methylene blue. Within the framework of this study, 60 permanent teeth (20 human, 20 dogs and 20 bovine) were used. These groups were evaluated statistically, of which indicated no statistically significant differences (p > 0.05). It was also concluded that this preliminary investigation showed that the new microleakage volume measurement method may be a valuable new technique for the in vitro study of microleakage dynamics around dental restorations.