Journal of Research in Dental and Maxillofacial Sciences
Volume:8 Issue: 3, Summer 2023

This study aimed to assess the effect of horizontal cantilever on microgap and microleakage at the implant-straight abutment interface in cement-retained crowns.   

In this experimental study, 12 implant-abutment assemblies and 12 cement-retained crowns were evaluated. The implant fixtures were bone-level, and had 10 mm length and 4 mm diameter. Straight titanium abutments had 7 mm length, 4 mm diameter, and 1 mm gingival height with Morse-Taper connection. Two groups were evaluated: 6 cement-retained crowns with a horizontal cantilever (test group) and 6 cement-retained crows without a horizontal cantilever (case group). The assemblies underwent load cycling in a chewing simulator. Cyclic load (75 N) with 1 Hz frequency was applied along the longitudinal axis of each specimen to the triangular ridge between the mesiobuccal and mesiolingual cusps of the crown. The amount of microgap before and after cyclic loading, and the microleakage score after immersion in fuchsine were evaluated under a light microscope.  Data were compared by t-test (alpha=0.05).

The change in microgap after cyclic loading compared with before was not significant in the control group (P=0.724). However, in the case group, the amount of microgap significantly increased after cyclic loading compared with before (P=0.000). Microleakage in the case group was significantly greater than that in the control group (P=0.019).

Horizontal cantilever caused horizontal microgap and increased the microleakage at the implant-straight abutment interface.

This study compared the flexural strength (FS) of heat-cure acrylic resin following one- and two-step processing techniques in dry and wet conditions.  

In this in vitro study, 60 acrylic specimens (3×10×65 mm) were fabricated (ISO20795-1) and flasked using a type III dental stone. The specimens were heated to 70°C for one hour and baked for 30 minutes at 100°C. After cooling and polishing, 30 specimens were randomly selected; of which, 15 were stored in 37°C water, and 15 in dry condition for one month. The remaining 30 were flasked again, baked, and divided into two subgroups for storage in dry and wet conditions. The FS of specimens was measured by a universal testing machine. Data were analyzed by one-way ANOVA and Tukey's post-hoc test (α=0.05).

The mean FS was 57.5±4.8 MPa and 61.7±4 MPa for specimens subjected to one-step processing and stored in wet and dry conditions, respectively. These values were 56.6±4 MPa and 64.7±2.9 MPa for specimens subjected to two-step processing and stored in wet and dry conditions, respectively (P<0.05). The difference in FS of specimens stored in dry and wet conditions was significant (P<0.05).

The two-step processing technique increased the FS while water storage decreased the FS of acrylic resin. FS of specimens subjected to one-step processing with water storage was slightly higher than that of specimens subjected to two-step processing with water storage. FS experienced a greater reduction following two-step processing in a wet environment compared with one-step processing.

This study aimed to assess the effect of calcium hydroxide (CH) in combination with betamethasone or ciprofloxacin on Enterococcus faecalis (E. faecalis) biofilm.  

This ex vivo experimental study was conducted on 95 single-rooted human teeth. The root canals were prepared and inoculated with E. faecalis. The samples were incubated for 8 weeks, and biofilm formation was confirmed by observation of 2 samples under a scanning electron microscope (SEM) and culture in 3 samples. The remaining samples were divided into three groups (n=30): CH + betamethasone eye drop, CH + ciprofloxacin eye drop, and CH + saline. Microbial analysis was performed at 1, 7 and 10 days. The colony count was measured. Comparisons were made by two-way ANOVA and a post-hoc test using SPSS.

On day 1, the highest colony count was observed in CH + saline group. The difference in colony count between CH + ciprofloxacin and CH + betamethasone, and the difference between CH + betamethasone and CH + saline were not significant at days 7 and 10. CH + ciprofloxacin showed significantly lower colony count than CH + saline at 1 (P=0.001), 7 (P=0.004) and 10 (P=0.002) days.

The result of this study showed that betamethasone and ciprofloxacin were appropriate carriers for CH and resulted in suitable antibacterial effects against E. faecalis.

Studies conducted on the Iranian population have mainly focused on tooth eruption or estimation of chronological age of children. This study aimed to assess the time of onset and completion of calcification of permanent teeth in an Iranian subpopulation.  

This descriptive, cross-sectional study was performed on 778 panoramic radiographs of subjects presenting to a public clinic in Tehran. Date of birth and exact date of taking the radiograph were recorded. The Demirjian’s method was used for determination of dental developmental stage. The median age for different calcification stages was separately determined for the maxillary and mandibular teeth. Time of each calcification stage in the maxilla and mandible in males and females was compared using the Wilcoxon signed rank test and independent sample t-test.

The chronological age of subjects was between 3 to 18 years. The median age for different developmental stages of teeth was determined. All developmental stages began sooner in the mandible (P<0.05). In comparison of males and females, no significant difference was noted in development of maxillary central incisors and first molars and mandibular central and lateral incisors and first molars (P>0.05). Completion of crown and root of other teeth specially the canines occurred faster and terminated sooner in females than males (P<0.05).

The present results showed that the development of teeth in female children occurred sooner and in a different order. This difference was more significant in development of root of last erupted teeth during late mixed dentition period.

The aim of this study was to compare two nickel-titanium (NiTi) closed coil springs (CCSs) from two different manufacturers regarding their force degradation over 4- and 8-week periods.   

In this in vitro experimental study, 20 NiTi CCSs from 3M® and GAC® were compared. The springs were extended until a tensile strength of 250 g was achieved, and the length of springs was recorded. They were then mounted on customized jigs according to the registered length, so as to keep them extended constantly. Springs from each manufacturer (n=10) were randomly divided into two subgroups (n=5): one subgroup was stored in artificial saliva and the other was stored in a dry environment. The forces were assessed 4 and 8 weeks later. Data were analyzed by repeated measures ANOVA and the Tukey post-hoc test (alpha=0.05).

The mean force of 3M® CCSs significantly decreased by 56% after 4 weeks and 14% after 8 weeks in dry condition, and by 46% after 4 weeks in wet environment; however, after 8 weeks in wet environment, the force decay was insignificant. The changes in force of GAC® CCSs in dry environment after 4 weeks and 8 weeks were not significant, indicating a constant force property. However, in artificial saliva, a statistically significant yet mild increase in force level was recorded.

The results showed a force decay for the 3M® CCSs after 4 weeks while for the GAC® CCSs, an almost constant force level was observed even after 8 weeks.

The main goal of root canal treatment is to three-dimensionally seal the root canal system. Since sealer may contact the periapical tissue, it should be biocompatible and safe for the body. This study aimed to assess the cytotoxicity of MTA Fillapex and Endoseal MTA calcium silicate-based sealers and AH Plus resin-based sealer for human gingival fibroblasts (HGFs).   

 In this in vitro study, extracts of AH Plus, Endoseal MTA, and MTA Fillapex were obtained, serially diluted 1:2, 1:4, and 1:8, and were exposed to HGFs. Cytotoxicity was assessed by the methyl thiazolyl tetrazolium (MTT) assay. Data were analyzed by ANOVA and Tukey’s test (alpha=0.05).

No significant difference existed between AH Plus 1:2 and MTA Fillapex 1:2 concentrations regarding the cell viability percentage (P>0.05). However, the difference between these two sealers in other concentrations was significant (P<0.05). No significant difference existed in AH Pus 1:4, Endoseal MTA 1:2, and MTA Fillapex 1:2 in cell viability (P>0.05); however, the difference among other concentrations of the three sealers was significant (P<0.05). The difference among AH Plus 1:8, Endoseal MTA 1:4, and MTA Fillapex 1:4 and 1:8 concentrations was not significant (P>0.05) but the difference among other concentrations was significant (P<0.05). Endoseal MTA 1:8 showed the highest and AH Plus 1:2 showed the lowest cell viability.

Endoseal MTA in all concentrations had lower cytotoxicity than MTA Fillapex and AH Plus and resulted in higher viability of HGFs.

Dental surgeons are responsible for each and every step taken for dental treatment of patients. The aim of this study was to assess the knowledge, experience, and perception of dental students and practitioners regarding dento-legal aspects of dentistry.  

A total of 200 students and dental practitioners were selected from the Chennai colleges. A well-structured validated questionnaire comprising of 21 questions related to dento-legal aspects of dentistry was used for data collection to assess the knowledge, experience, and perception of participants regarding dento-legal aspects of dentistry, which included clinical scenario-based questions. The responses were tabulated and analyzed using OpenEpi software. All variables were analyzed descriptively.

Out of 200 participants surveyed, 53.6% were dental practitioners and 46.4% were dental students. Of all, 75% of dental practitioners and students were well aware of the dento-legal issues. Also, 50% of undergraduates and 65% of postgraduates were aware of their rights to protect themselves in legal cases. More than 50% of dental practitioners and students were aware of how to manage mishaps in a dental clinic. Out of 200 participants, 70% of dental practitioners and students were aware of the rules and regulations, and liabilities related to their practice.

Considering the present results, more emphasis should be placed on raising awareness among undergraduates regarding dento-legal aspects of dentistry and prevention of mishaps due to negligence during treatments.

Displacement of a tooth or part of it into the adjacent anatomical structures is a serious complication of oral surgical procedures. Herein, we report intraoral management of a root displaced into the submandibular space.  

A 46-year-old female was referred by a dentist to the department of oral and maxillofacial surgery for management of a displaced right mandibular third molar root into the submandibular space. The patient had undergone unsuccessful extraction of the tooth under local anesthesia 2 weeks earlier. On clinical examination, the floor of the mouth was tender on palpation, and slight edema was noted extra-orally at the right mandibular angle. Panoramic radiography and cone beam computed tomography (CBCT) were requested, which showed presence of a residual root segment (high density mass) in the right submandibular region. The dislodged root was removed intraorally under general anesthesia without any postoperative complication.

Displacement of tooth/tooth fragments into anatomical spaces after molar extraction can be avoided by adequate preoperative evaluation of patient and adoption of a meticulous surgical technique by an expert oral surgeon.

Oral giant cell fibroma (GCF) is a benign fibrous tumor that is histologically characterized by large, stellate, and mono- or multinucleated giant cells. GCF is an asymptomatic, sessile, or pedunculated exophytic lesion, usually smaller than 1 cm, with a smooth or papillary surface and the same color as the oral mucosa. The role of trauma in development of GCF has been contradictory. Knowledge about the characteristics of this lesion can help in diagnosis, treatment and follow-up of patients.  

This article describes five cases of GCF in Iranian patients, two of which were found in an uncommon location (buccal mucosa). Two were larger than usual (> 1 cm) and one had clinical manifestations resembling pyogenic granuloma. Patients were selected from two oral medicine centers.

To distinguish GCF from other types of irritation fibroma, size, location, and presence or absence of stimulating factors should not preclude diagnosis. The diagnosis is confirmed by detection of giant cells in histological examination.

With the advances in technology, the use of natural materials has broadened. Acemannan is the main polysaccharide in aloe vera plant. It is a natural and biocompatible polymer with low toxicity. The acemannan monomers include mannose, glucose and galactose. Due to its biological properties, acemannan could be useful in bone regeneration.  The aim of this study was to investigate the effect of acemannan/aloe vera on bone regeneration and extraction socket healing.  

In this review article, an electronic search was conducted in PubMed and Scopus from 1996 to June 2022. Relevant data based on clinical indications were extracted. Twenty original articles, including 4 in vitro studies, 8 animal, and 8 human studies were reviewed. The inclusion criterion was articles that directly and originally evaluated the correlation of bone regeneration and acemannan/aloe vera.

Over 30 studies were found in this field by database searching. According to the results, the proposed items could be categorized into 3 major groups of animals, human, and in vitro studies. Animal studies were divided into two groups of bone defect regeneration and extraction socket healing. Also, human studies were divided into two groups of bone defect regeneration and sinus floor elevation/guided bone regeneration surgeries. All studies reported positive effect of Acemannan/aloe vera on bone healing and regeneration.

Acemannan/aloe vera may be considered as a bioactive molecule due to induction and acceleration of bone formation.