Retention of Cast Posts Cemented with Two Commonly Used Conventional and Two Resin Cements and the Mode of Root Fracture Following Their Removal.

Objectives: This study aimed to compare the retention of cast posts cemented with four types of cements and assess the mode of root fracture following their removal. Materials and Methods: In this in vitro, experimental study, 48 upper central incisors were randomly divided into 4 groups of 12, and were endodontically treated. The fabricated cast posts in each group were cemented with zinc phosphate (Masterdent), glass ionomer (GI; Meron), Meta resin cement, and Panavia SA resin cement. A device was customized for post removal by a universal testing machine similar to WAM X pliers. The retention of cemented posts was measured by the pull-out test in a universal testing machine. Next, the teeth were macroscopically and microscopically inspected regarding the occurrence and sites of catastrophic fracture, cracks, or craze lines. Quantitative and qualitative data were analyzed by ANOVA, and Chi-square test, respectively (P<0.05). Results: ANOVA showed a significant difference in the mean retention of cements (P<0.001). Panavia provided the highest retention (278.6±34.9 N) followed by zinc phosphate (221.9±28.88 N), GI (161.3±60.7 N), and Meta (140.4±66.54 N). There was no significant difference between the groups regarding the pattern of root fracture (P=0.39). However, site and extent of fractures were significantly different among the groups (P<0.05). Conclusion: The conventional cements provided optimal retention and caused less root damage after post removal. Thus, cements providing adequate retention and allowing easier post removal are recommended for use in endodontically treated teeth with a possibility of requiring retreatment.

Effect of photo core, LuxaCore, and core max II core building materials on fracture resistance of endodontically-treated teeth restored with fiber-reinforced composite posts and ParaPosts.

BACKGROUND: Post and core treatment is commonly performed for endodontically treated teeth to replace the lost tooth structure and reinforce and protect the remaining dental tissue. This study aimed to compare the effect of three-core building materials on fracture resistance of endodontically-treated teeth restored with fiber-reinforced composite (FRC) posts and ParaPosts. MATERIALS AND METHODS: This in vitro, experimental study evaluated 108 sound, single-rooted mandibular first premolars extracted for orthodontic purposes. The teeth were randomly divided into nine groups (n = 12) of control (no endodontic or restorative treatment), FRC + Photo Core (Group 2), FRC + LuxaCore (Group 3), FRC + Core Max II with bonding agent (Group 4), FRC + Core Max II without bonding agent (Group 5), ParaPost + Photo Core (Group 6), ParaPost + LuxaCore (Group 7), ParaPost + Core Max II with bonding agent (Group 8), and ParaPost + Core Max II without bonding agent (Group 9). The fracture resistance was measured by applying the load at 45° angle relative to the longitudinal axis of the tooth with a crosshead speed of 1 mm/min using a universal testing machine. Data were through descriptive statistics, Tukey's test, and one-way analysis of variance (α = 0.05). RESULTS: The mean fracture resistance was 454.0 ± 62.7, 410.8 ± 48.3, 365.1 ± 42.1, 423.7 ± 111.7, 392.4 ± 90.0, 292.3 ± 83.9, 242.3 ± 73.4, 278.2 ± 67.9, and 247.3 ± 49.6 N in Groups 1-9, respectively. Group 4 showed the highest fracture resistance, which was significantly higher than this study the value in all ParaPost and control groups (P < 0.05) but had no significant difference with the fracture resistance of other groups (P > 0.05). CONCLUSION: Fracture resistance is independent of the type of core building material used, and the tested products had no superiority over each other. The mean fracture resistance of FRC post groups were significantly higher than that of ParaPost groups. Furthermore, Core Max II + bonding agent yielded insignificantly higher fracture resistance than Core Max II without bonding agent.

Effect of dental implantation on the hard and soft tissues around the adjacent natural teeth.

BACKGROUND: Dental implantation has become widespread for esthetic and functional rehabilitation following single tooth loss as a preferred alternative to conventional tooth-supported restorations. The main advantage of dental implant placement is that it does not require the preparation of the adjacent sound teeth. OBJECTIVES: The aim of this cohort study was to assess the effect of dental implantation on the hard and soft tissues around the adjacent natural teeth. MATERIAL AND METHODS: In this historical cohort, 34 'connect-type' TBR® implants (bone level), 4 mm in diameter, were submerged in the intact bone of 22 patients (7 males and 15 females). The intraoral and extraoral clinical examination as well as periapical radiography were carried out preoperatively or right after surgery (baseline), at 3 months postoperatively (the time of prosthetic delivery), and at 3 and 6 months after prosthetic delivery. The data was analyzed using the Friedman test (due to the non-normal distribution of the data). In case of presence of a significant difference, pairwise comparisons were performed using the post-hoc Wilcoxon test with the Bonferroni correction. All statistical analyses were performed with a 95% confidence interval (CI) using the SPSS for Windows, v. 16.0 software. The p­value <0.05 was considered statistically significant. RESULTS: The distance from the cementoenamel junction (CEJ) of the adjacent teeth to the bone crest significantly increased at different postoperative time points compared to baseline (p < 0.001). The changes in the papillae of the adjacent teeth were also significant at different postoperative time points (p = 0.04). The pocket depth of the adjacent teeth increased, although the value at 3 months postoperatively was not significantly different from the baseline value (p = 0.842). The distance from the implant shoulder to the bone crest of the adjacent teeth significantly increased at different postoperative time points compared to baseline (p < 0.001). CONCLUSIONS: Our results indicate that implant surgery significantly affects the soft and hard tissues around the adjacent natural teeth.

Comparative Study of Dimensional Accuracy in Three Dental Implant Impression Techniques: Open Tray, Closed Tray with Impression Coping, and Snap Cap.

AIM: Several impression techniques have been proposed to result passive fitness between the prosthesis and osseointe-grated implant. The aim of the study was to compare dimensional accuracy of three impression methods: Open tray, closed tray with impression coping, and closed tray with snap cap. MATERIALS AND METHODS: In this experimental study, a mandibular acrylic model was prepared with a milling machine to place three holes for dental implant analogs (Dio SM) with the dimension of 3.8 × 10 mm into the intended sites (one in midline and two others on the side at a distance of 10 mm) parallel with each other and perpendicular to the plane. Twenty-seven casts were prepared with impression material of polyvinyl siloxane (PVS) and dental stone type IV and divided into three groups. Implant situations were measured by coordinate measuring machine (CMM) and results were analyzed with Kruskal-Wallis and Mann-Whitney test to perform pairwise comparison among the groups. RESULTS: The mean ΔR values for open tray, closed tray with impression coping, and closed tray with snap cap were respectively, 0.070 ± 0.088, 0.173 ± 0.205, and 0.142 ± 0.044. There were statistically significant differences between open tray and closed tray as well as open tray and snap cap methods (p < 0.05), but there was no statistically significant difference between closed tray and snap cap method (p = 0.1). CONCLUSION: Regarding the results, open tray impression technique had the highest dimensional accuracy compared with the other two methods. There were no statically significant differences between closed tray with snap cap and closed tray with impression coping technique. CLINICAL SIGNIFICANCE: Snap cap technique is less time consuming with similar dimensional accuracy in comparison with open tray impression technique.

Immediate vs. delayed endosseous integration of maxi implants: a torque removal animal study.

Background. Delayed loading is one of the concerns in implant patients. Immediate loading can solve the problem and make patients more satisfied. The present study aimed to compare the removal torque of maxi implants under different loading (immediate and delayed) patterns. Methods. This split-mouth experimental study included 2 dogs. Impressions were made and then all the premolars were extracted under general anesthesia. After a three-month healing period, 3 implants were inserted in each quadrant (a total of 12 implants). Anterior and posterior implants (the case group) were splinted by an acrylic temporary bridge in order to make the middle implants (the control group) off the occlusion. The dogs were sacrificed after 6 weeks and bone blocks were submitted for removal torque test. Data were analyzed with ANOVA (P<0.05). Results. Mean torque values for the cases and control groups were 46.82±25.58 and 59.88±15.19, respectively (P=0.582; not significant). Conclusion. It may be concluded that immediate loading does not reduce the reverse torque values of maxi implants. This supports the advantages of immediate loading for maxi implants.

Edentulous child with Allgrove syndrome: a rare case report.

Triple-A syndrome, also known as Allgrove syndrome, is a rare autosomal recessive disorder. The 3 features of this syndrome are achalasia, adrenal insufficiency, and alacrima. Achalasia could be the first manifestation of the triple-A syndrome; however, its etiology is unclear. Alacrima is generally asymptomatic but can be detected by obtaining patient history. Although adrenal insufficiency could have manifestations such as asthenia, it might be wrongly diagnosed as muscle fatigue. Vitamin D and calcium supplements are usually prescribed for the prevention of osteoporosis. Neurologic manifestations could be present in adults. In some individuals with this disorder, genetic examination indicates mutations in both alleles of the AAAS gene, which encodes a special 546-amino-acid protein designated ALADIN, and in chromosome 12q13. The genetic cause of the triple A syndrome in some patients who do not have an identified mutation is unknown. While very few such cases have been reported till date, one such case was presented to us as an edentulous child.

A Multidisciplinary Approach to a Seven Year-Old Patient with Incontinentia Pigmenti: A Case Report and Five-Year Follow Up.

Incontinentia pigmenti is a rare inherited disorder involving abnormalities of the skin, hair, eyes, musculoskeletal system, central nervous system, and the teeth. Dental abnormalities are the most common manifestations of this disorder. The purpose of this case report was to present the clinical and radiological findings of a seven-year-old girl as well as the results of her five-year follow up. The patient showed faded linear pigmented macular lesions on the trunk and on upper and lower limbs. Dental examination was notable for conical and peg-shaped anterior teeth as well as delayed eruption of primary and permanent teeth. In addition to conservative treatments, prosthetic treatments such as interim removable partial dentures were indicated for the patient.

Water Sorption and Flexural Strength of Thermoplastic and Conventional Heat-Polymerized Acrylic Resins.

OBJECTIVES: The aim of this study was to assess and compare the water sorption and flexural strength of thermoplastic and conventional acrylic resins. MATERIALS AND METHODS: Water sorption and flexural strength were compared between a thermoplastic modified polymethyl methacrylate (PMMA) denture base resin (group A) and a heat-polymerized PMMA acrylic resin (group B) as the control group (n=10). A three-point bending test was carried out for flexural strength testing. For water sorption test, 10 disc-shaped samples were prepared. After desiccating, the samples were weighed and immersed in distilled water for seven days. Then, they were weighed again, and desiccated for the second and third times. Differences between the mean values in the two groups were analyzed using Student's t-test. RESULTS: The mean value of water sorption was 14.74±1.36 µg/mm(3) in group A, and 19.11±0.90 µg/mm(3) in group B; this difference was statistically significant (P< 0.001). The mean value of flexural strength was 88.21±8.63 MPa in group A and 77.77±9.49 MPa in group B. A significant difference was observed between the two groups (P= 0.019). CONCLUSION: Flexural strength of group A was significantly higher than that of group B, and its water sorption was significantly lower. Thus, thermoplastic resins can be a suitable alternative to conventional PMMA acrylic resins as denture base materials.