Journal of Dental Research, Dental Clinics, Dental Prospects
Volume:13 Issue: 2, Spring 2019

The design of an orthodontic mini-implant is a significant factor in determining its primary stability and therefore its clinical success. The purpose of this study was to measure the relative influence of mini-implant design factors including diameter, length, degree and length of taper both in the threaded and non-threaded area, pitch and thread depth/diameter on the primary stability. Thirty two 3-dimensional assemblies of mini-implant models with their surrounding bone were generated using finite element analysis software. The maximum displacement of each mini-implant model was measured as they were loaded with a 2 N horizontal force. Employing Taguchi’s design of experiments as a statistical method, the contribution of each design factor to primary stability was calculated. As the effect of the upper diameter and length was abundant, to better detect the impact of the remaining design factors, another set of twenty five models with a fixed amount of length and diameter was generated and evaluated. The diameter and length showed a great impact on the primary stability in the first set of experiments (p<0.05). The effect of the remaining factors was not statistically significant. According to the second set of experiments, threaded taper angle, non-threaded taper angle and non-threaded taper length were the main factors influencing the primary stability, respectively. An approximate proportion of 20% of threaded taper length to MI length, with minimum taper angle, would be desirable for an average-sized MI.

Monolithic zirconia is an emerging material for crowns and bridges. Possibility of full digital design has made it an attractive alternative material for implant supported prostheses. A proper design is vital in the success of such prosthesis like any other. This study, in the shortage of scientific evidence, has tried to assess the stress distribution of occlusal forces inside the implant-prosthesis system of a 3-unit bridge made of monolithic zirconia. A 3-unit monolithic zirconia bridge supported by two implant fixtures placed on the teeth number 13 and 15 was digitalized. It was converted to a mesh of 59000 nodes and 34000 elements. Five types of occlusal forces (one as vertical centric, two on 15 and 30 degrees assuming canine pattern of lateral movement, and two on 15 and 30 degrees assuming group function pattern) were applied. The stress distribution among all components of the implant-bridge system was assessed using Ansys Workbench 14 software and finite element analysis. the maximum stress was between 286 and 546 MPa which were found in either the fixture-abutment screw area or in the upper part of the pontic connector between canine and first premolar. The amount of maximum pressure was increased by increase in the angle of occlusal force. Notable higher stress was recorded in the group function occlusal pattern. Monolithic zirconia can be promising in designing bridges in the canine-premolar area. However, proper design is necessary with more attention to be paid to the connectors and types of occlusal forces.

The porcelain is brittle and in many situations requires replacement in fractured or chipped restorations. The prospects exist in improving the strength of feldspathic porcelain to widen its applications. This study evaluated the fracture toughness of feldspathic porcelain, incorporated with silver and titanium nanoparticles at varying concentrations (0.5wt%, 1wt%, 1.5wt%, 2wt %). Test specimen dimensions were standardized to ASTM C1421 – 16 standards and a three-point flexure test was done to evaluate fracture toughness. 330 samples were fabricated and were broadly divided into three groups. Group I (titanium nano particles) and Group II (silver nano particles) were further subdivided into 5 groups(0wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt %) for fracture toughness analysis and each group consist of 30 samples. Group III contained the superior concentration of both titanium and silver nanoparticles. The fracture toughness (KIC) was calculated using indentation fracture method and microstructure observations were made with scanning electron microscopy. The observed values of KIC were compared and evaluated using 1-way ANOVA. The results obtained were analyzed using one-way analysis of variance (ANOVA) and Tukey’s HSD Post hoc test multiple comparisons test. The mean values of Group I, Group II and Group III were found to be 1.949 MPa.m1/2, 2.002 MPa.m1/2 and 1.330 MPa.m1/2. The test results revealed that the samples reinforced with titanium and silver nanoparticles showed significant increase in fracture toughness. The blending of superior concentration of both titanium and silver nanoparticles lead decreased the fracture resistance.

The temperature might affect the physical and mechanical properties of the adhesive material by reducing the polymerization. The present study aimed to evaluate the effect of temperature on the shear bond strength of metallic orthodontic brackets in various adhesive resin systems. Extracted human premolar teeth were randomly allocated to 8 groups (n=10) for bonding with the two available orthodontics adhesive systems (Transbond XT and NeoBond) at different temperatures: refrigeration temperature (4 °C), room temperature (20 °C), human body temperature (36 °C), and high temperature (50 °C). The shear bond strength (SBS) test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The Adhesive Remnant Index (ARI) was assigned to the fractured orthodontic brackets. Data were analyzed using one-way ANOVA, the Tukey’s post-hoc test, and independent t-tests. Transbond XT had higher SBS values than Neobond at all the tested temperatures; however, a statistically significant difference was not observed (P>0.05). The SBS results were minimal at 4 °C and maximal at 36 °C in both the adhesive groups (P<0.05). Heating of orthodontic adhesives to body temperature prior to bonding the brackets in the orthodontic treatment increases the bonding strength of the orthodontic brackets.

When implant fractures occurs, it can cause difficult problems for patients and dentists. This systematic review aimed to determine the influence of some implants parameters in the occurrence of their fracture and to determine the incidence of fractures reported in recent years. A search was conducted in Pubmed database, from which 12 studies published in the last 12 years were selected. This review reported a 2% incidence of implant fracture. Most implants were in function between 3 and 4 years until the moment of fracture. The studies do not provide necessary information to establish a relationship between the different parameters of implants and the incidence of fractures. Thus, the indication of type, diameter and length of an implant and the bone quality in the region that will receive it should be studied and accurately examined for each individual case in order to avoid future failures.

This study evaluated the viability of platelet rich plasma on enhancement of osseous and associated soft tissue healing around single piece implants, subjected to immediate loading and to compare it with control site that is not treated with PRP. Total of 20 completely edentulous patients were selected and 2 one piece implant with o ball head were place for mandibular overdenture. Implant on the right side was treated with PRP whereas left side implant acted as control. All cases were immediately loaded and marginal bone loss, probing depth, percussion, implant mobility, peri-implantitis was assessed and compared at 3, 6,9,12 months. Overall analysis of study showed less marginal bone loss, probing depth, percussion, implant mobility, peri-implantitis around implants treated with PRP, however statistically the results were insignificant. PRP can be used as a viable treatment adjunct in immediately loaded one piece implants.

Elevated temperature has been recognized as an inflammatory sign, the only indication that can be both objectively and quantitatively evaluated, and is considered as a potential indicator of periodontal disease. Assessing gingival surface temperature (GST) could be a diagnostic parameter to determine periodontal health. This pilot clinical study aimed to validate gingival surface temperature (GST) as a clinical diagnostic tool to measure periodontal disease activity by correlating with the periodontal inflamed surface area (PISA). A cross-sectional mono-centric pilot study was conducted with a convenient sample of 50 participants with a mean age of 34.14±13.7 years. Clinical parameters such as probing pocket depth (PPD) clinical attachment loss (CAL), bleeding on probing (BOP) were measured. GST was recorded with a single lead of the bedside patient monitor and correlated it with PISA. The results showed a positive correlation between PISA and GST (P = 0.46). This study showed a rise in GST of inflamed sites, but the results did not support the hypothesis that increased GST is an indicator of periodontal disease. As this is a pilot study, furthermore studies with more significant sample size need to be done to confirm its use as a diagnostic tool in clinical trials. The trial has been registered with Clinical Trials Registry-India-CTRI/2018/05/014169.

Temporomandibular joint dysfunction (TMD) is a term that describes problems in the masticatory system, including the temporomandibular joint, the dento-muscular system and the supporting bones. Injection of botulinum toxin, as a noninvasive technique, might be useful in decreasing symptoms such as muscular spasm, dystonia, migraine headaches and TMD. Therefore, the aim of the present study was to evaluate the effect of injection of botulinum toxin on decreasing the symptoms and signs of masticatory muscles in patients with TMD. A total of 61 patients were consecutively included in the present study in 2016‒2017. All the subjects received a 50-unit injection of Dysport botulinum toxin in the masseter muscles using an extraoral injection technique. The results of the injection were evaluated in terms of pain severity using VAS, clinical evaluations of the joint click through palpation and by determining the inter-incisal distance. The patients underwent follow-up examinations at 1-week, 3-month and 6-month intervals after injection. Data were analyzed with appropriate statistical tests. Comparison of pain severity and articular clicks at different intervals showed decreases in these parameters over time, with significant differences between the time intervals (P<0.05). Comparison of mouth opening at different intervals showed increases in mouth opening over time. The results of the present study showed that injection of botulinum toxin can be used in patients with TMD as a non-invasive treatment modality.

The purpose of this study was to compare the postoperative pain intensity following the root canal preparation carried out with XP-endo Shaper (XPS; FKG Dentaire SA, La Chauxde-Fonds, Switzerland), iRace (iRC; FKG Dentaire SA) and Reciproc Blue (REC Blue; VDW, Munich, Germany) files. Mandibular molar teeth with asymtomatic necrotic pulp of 69 patients were randomly divided into three groups. (n:23) The root canals were prepared using XPS, iRC or REC Blue instruments and obturated using the lateral condensation technique. The VAS was given to the patient and the patients were asked for recording the pain on 24th, 48th, and 72nd hours and 1 week after the treatment. For intolerable pain after the procedure, ibuprofen (400 mg) was prescribed. The data were analyzed using chi-squared, Friedman, Kruskal–Wallis, and Mann–Whitney U tests. The postoperative pain level gradually decreased during the study period in all the groups (P <.05). No statistically significant difference was found between iRC system and other two systems in 12h, 24h, 48h and 1-week periods (P>.05). When compared to XPS system, a higher level of postoperative pain was observed with REC Blue system in 24h and 48h periods (P <.05). The XPS group had less postoperative pain than the REC Blue group in 24h and 48h periods. iRC system and XPS and REC Blue systems were found to be similar in terms of the postoperative pain severity.

Severely damaged teeth do not have enough crown structure to support the composite crown, then, using canal space has been suggested for retention. This study compared the fracture resistance of the primary anterior teeth restorations with severe destructions following irrigation protocols of post space with sodium hypochlorite and chlorhexidine with and without bur applying. In this invitro study 94 primary anterior teeth were selected. The root canal treatments were done, 4mm of the post space were left empty and 1mm of them were regarded as their bed. The post space was prepared with and without bur using and washing protocols were done with 0.2% chlorhexidine and 2.5% sodium hypochlorite. Composite posts were inserted in the canals and the crowns were restored. Following composite etching and light-curing, the fracture resistance of the restored teeth was determinated by UTM device. The effects of bur and washing protocols on fracture resistance were analyzed. When washing post space with sodium hypochlorite, fracture resistance of the teeth was 376.8+107.29 N and 475.5 +186.89 N without and with bur preparations. For the chlorhexidine protocols, the values were 370.88+175.46 N and 430.85+178.22 N without and with bur preparation respectively. The effect of irrigating material on the fracture resistance was not significant, however, the bur and irrigating preparation significantly increased the fracture resistance of the restored teeth (p=0.02). The post space irrigation with 0.2% chlorhexidine or 2.5% sodium hypochlorite did not significantly affect the fracture resistance of primary anterior teeth in post treatment modality.

Fluoride releasing capacity has been added to fissure sealants to have the positive anti-decay effects of both sealant and fluoride. This research is aimed at comparatively study the inhibitory effects of conventional and fluoride-releasing fissure sealants with or without exposure to fluoride toothpaste on primary carious lesions. Cavities were created on buccal surfaces of 24 premolar teeth which were randomly divided into three groups. In the cavities of the first group, fluoride releasing fissure sealant and in the second group, conventional fissure sealant were put, and the third group was left intact. Early lesions were produced around the cavities. Each group was divided into two subgroups, which were exposed to fluoride-containing toothpaste or artificial saliva. The depth of lesions were measured under polarized light microscope before and after treatment. Change of lesion depth in each sample was analyzed by SPSS 17 software. Initial and final caries depths were significantly lower in fluoride-releasing fissure sealant group than the others (p<0.001). The average depths of caries were less in subgroups which were exposed to fluoride-containing toothpaste than the subgroups exposed to artificial saliva and the difference was significant in conventional sealant group and the group without sealant (p<0.001), however, the difference between toothpaste-exposed and saliva-exposed subgroups was not significant in fluoride-releasing fissure sealant group (p=0.721). Adding fluoride to the fissure sealants can be effective in the inhibition of dental caries. It seems that fluoride, released from fluoride-releasing sealants, overwhelm the remineralizing capacity of fluoride released from toothpaste, on the same tooth.