A comparative study to evaluate surface electromyographic correlations of mandibular implant-supported overdentures to conventional complete dentures in edentulous patients: An in vivo study.

Aim: The aim of this study was to compare the function and coordination of masticatory muscles for patients with two implant-supported mandibular overdenture (ISOD) with that of conventional complete dentures (CCD) using surface electromyography (sEMG). The objectives were to assess the muscle activity (efficiency) and clinical outcome after the transition of CCD patients to ISOD. Setting and Design: This was a crossover study. Materials and Methods: This clinical trial was conducted in the department of prosthodontics. A total of 15 patients (nine males and six females) were assessed using sEMG. In each patient, a total of four surfaces were examined above the following muscles - right and left masseter and right and left temporalis muscles. The electromyography readings were recorded to assess muscle activity during Clenching, cotton roll clenching, and chewing. The readings were recorded first for CCD and then for ISOD (after installing attachments). Statistical Analysis Used: Data analysis was done using independent t-test and one-way ANOVA. Results: Mean muscular activity of masseter during clenching, cotton roll clenching, and chewing for patients with ISOD (44.3 ± 11.2 µV, 41.1 ± 13.4 µV, and 45.2 ± 17.5 µV) was higher than CCD (26.0 ± 11.3 µV, 22.6 ± 9.7 µV, and 24.2 ± 9.5 µV). The mean muscular activity of temporalis during clenching, cotton roll clenching, and chewing was also higher with ISOD (47.9 ± 11.2 µV, 45.6 ± 11.9 µV, and 51.0 ± 14.4 µV) than CCD (31.0 ± 12.2 µV, 29.7 ± 15.3 µV and 31.9 ± 14.2 µV). No statistically significant result was found between masseter and temporalis muscle activity on both sides (P < 0.05), indicating symmetrical activity on both the sides. Conclusion: Two-ISODs prove to be a better and efficient treatment modality in rehabilitating edentulous patients as it enhances retention and also increases masticatory muscle activity and chewing efficiency.

Effect of cigarette smoke on the surface roughness of two different denture base materials: An in vitro study.

AIM: This study aimed to evaluate the effect of cigarette smoke on the surface roughness of two commercially available denture base materials. MATERIALS AND METHODS: A total numbers of 40 specimens were fabricated from two commercially available denture base materials: heat-cured polymethylmethacrylate and flexible denture base materials (20 for each). The specimens for each type were divided into four subgroups: subgroup I, heat-cured denture base material specimens (control group); subgroup II, flexible denture base material (control group); subgroup III, heat-cured denture base material specimen exposed to cigarette smoking group; and subgroup IV, flexible denture base material specimens exposed to cigarette smoking. The control groups were used for immersion in distilled water, and the smoke test groups were used for exposure to cigarette smoking. The smoke test group specimens were exposed to smoking in a custom-made smoking chamber using six cigarettes for each specimen. The surface roughness was measured using a profilometer, and the measurements were considered as the difference between the initial and final roughness measured before and after smoking. Paired t test and independent t-test were used to interpret differences in initial and final roughness values within and between groups respectively. RESULTS: Paired t-test showed a significant difference between initial surface roughness and final surface roughness within each subgroup. CONCLUSION: The surface roughness of the specimens fabricated from the flexible denture base material was found to be more compared to heat-cured denture base specimens after exposure to cigarette smoke.

A comparative evaluation of chewing efficiency, masticatory bite force, and patient satisfaction between conventional denture and implant-supported mandibular overdenture: An in vivo study.

PURPOSE: The purpose of this within-subject crossover clinical trial was to compare and evaluate the chewing efficiency, masticatory bite force, and patient satisfaction with conventional dentures and two implant-retained mandible overdentures after 4 weeks of usage. METHOD: This within-subject crossover clinical trial was carried out in the Department of Prosthodontics in K.D Dental College and Hospital. A total 15 patients were selected for the study. To report the changes in chewing efficiency by chewing 6gms of peanuts with 40 chewing strokes and comparing the particle size of the chewed material between two implant retained mandibular overdenture with that of conventional denture using micro vu excel gantry type visual measurement machine. To report changes in masticatory bite force after transition of conventional complete denture patient to implant retained overdenture after using the prosthesis for four weeks each and recorded by digital transducer. To assess the patient satisfaction after transition of conventional complete denture patient to implant retained mandibular overdenture with help of OHIP edent patient satisfaction questionnaire. RESULTS: The chewing efficiency for implant retained overdenture increased significantly than that of conventional denture. The particle size decreased to 76.34% for implant supported overdenture than that of conventional denture. The chewing strokes required by conventional denture was 69 strokes and that by implant supported overdenture which was 40 strokes to get the same mean particle size. The patients satisfaction after receiving the implant retained overdenture was significantly higher than that of complete denture. CONCLUSION: The provision of two mandibular implants significantly improves measures of oral function and better quality of life for edentulous patients.

The effect of surface treatments on the bond strength of a nonprecious alloy-ceramic interface: an invitro study.

The purpose of this study was to compare the effect of seven different alloy surface treatments on the bond strength of the porcelain-metal interface. Three layers of opaque porcelain and a measured thickness of dentin porcelain were applied to nickel-chromium alloy, A tensile bond strength test was used. The alloy surface treatment that exhibited the highest bond strength was sandblast + surface grinding + sandblast + de-gas, whereas the alloy surface treatment that exhibited the lowest bond strength was sandblast + surface grinding + sandblast + steam cleaning + de-gas. There was a significant difference between the two methods (P < 0.05). It was concluded that de-gassing the alloy prior to porcelain application increased the bond strength and excess surface grinding of the alloy reduced bond strength; steam cleaning the alloy surface prior to de-gassing and porcelain application also significantly reduced the bond strength.

An in vitro study to compare the accuracy of the master cast fabricated by four different transfer impression techniques for single-tooth implant replacement.

Single tooth implant retained crowns have become a recognized technique for the replacement of the missing teeth. With the predictable integration of implants, the emphasis is shifted towards precise prosthesis. Minor movement of the impression coping retained inside the impression material can occur during all the procedures, leading to the three-dimensional spatial inaccuracies in the master casts. Therefore, the present study was undertaken with the purpose to evaluate the accuracy of single-tooth implant impression techniques using four different impression copings, so as to obtain a precise definitive cast for a single-unit implant restoration. A maxillary acrylic resin model with a standard single implant in the first molar region was used to simulate a clinical situation. A total of 60 impressions were made with polyvinylsiloxane impression material, which were divided into four groups of 15 impressions each. Group I used non-modified square impression coping, while in group II, III and IV square impression coping were modified differently. Master casts fabricated for all the groups were analyzed to detect rotational position change of the hexagon on the implant replicas in the master casts in reference to the resin model. The master casts obtained with the roughened and adhesive-coated impression copings showed a lower amount of rotational movement than the masters casts achieved with the non-modified impression copings. Hence, the clinician should use sandblasted and adhesive coated impression copings to achieve a more accurate and precise orientation of the implant replicas in the laboratory master casts in single-tooth implant restorations.

A Comparative Evaluation of Dimensional Accuracy and Surface Detail Reproduction of Four Hydrophilic Vinyl Polysiloxane Impression Materials Tested Under Dry, Moist, and Wet Conditions-An In Vitro Study.

Vinyl polysiloxane (VPS) impression materials have application in a wide variety of situations in both fixed and removable prosthodontics. A major limitation of VPS impression materials is their hydrophobicity. There are two aspects of this problem, the wettability of the polymerized impression by dental gypsum materials and the ability of the unpolymerized material to wet intraoral tissues. To address this problem, manufacturers have added surfactants and labelled these new products as "hydrophilic vinyl polysiloxane." The purpose of this study was to evaluate and compare dimensional accuracy and surface detail reproduction of four hydrophilic VPS impression materials, when used under dry, moist, and wet conditions. A total of 180 samples were made of stainless steel die similar to as described in ADA sp. no. 19. The die was scored with three horizontal and two vertical lines. Impressions were made under dry, moist and wet conditions. Dimensional accuracy was measured by comparing the length of the middle horizontal line in each impression to the same line on the metal die, by using Universal Length Measuring machine. A 2-way ANOVA was performed on the percentage change data for measured lengths of the 4 impression materials under the 3 conditions to evaluate dimensional accuracy. Surface detail was evaluated in two ways: (1) by use of criteria similar to ADA sp. no. 19 for detail reproduction, and (2) by use of a method that categorized the impressions as satisfactory or unsatisfactory based on their surface characteristics: presence of pits, voids, or roughness. Pearson X2 (α = 0.05) was used to compare surface detail reproduction results. Conditions (dry, moist, and wet) did not cause significant adverse effects on the dimensional accuracy of all the four material. With both surface detail analyses, dry, moist, and wet conditions had a significant effect on the detail reproduction of all the four materials (P < 0.05). The study concluded that the dimensional accuracy of all the four impression materials tested was well within ADA standards. Best surface detail results were obtained only under dry conditions for all the four materials.

A Comparative Study to Evaluate the Compression Resistance of Different Interocclusal Recording Materials: An In Vitro Study.

Recording and transferring of accurate existing occlusal records is of prime importance for a successful restoration. An ideal occlusal registration material should provide minimal resistance to mandibular closure during the registration of maxillomandibular relationships. Interocclusal bite registration materials are partly responsible for accurate precision and occlusal quality of final prosthetic restorations when used for mounting casts on the articulators. The aim of selecting this study is to compare different types of recent interocclusal recording materials and to find the best among them which can resist a constant compressive load and will give the least inaccuracies. In the present study compressive resistance of four interocclusal recording materials viz. Imprint bite, Vitual refill, Jet bite and Ramitec at various thickness (2, 5, 10 and 20 mm) when subjected to a constant compressive load of 25 N was studied. The thickness of the interocclusal recoding materials were selected to simulate various clinical situations. For standardization, the specimens were stored at room temperature for 24 h to simulate the time between clinical and laboratory phases, N = 20 specimens from each group was selected (making a total sample size of N = 80). The SPSS version 17 has been used, two way ANOVA was applied to compare different types of recent interocclusal recording materials, p value ≤0.05 was considered statistically significant. A total of 80 samples were fabricated. Results of two-way analysis of variance (p ≤ 0.05) indicated that there was a significant difference in compressive resistance among the materials of each thickness. The 2 mm thickness specimens showed the least compression and 20 mm thickness specimen showed maximum compression under a constant load of 25 N for all the four materials tested. Virtual Refill bite registration material showed the least compression value than Imprint bite polyvinylsiloxane registration material, Ramitec polyether bite registration material and Jet bite polyvinylsiloxane registration material with negligible error of 0.04 mm found in 2 mm thickness. The results of foregoing study showed that Virtual refill having greater resistance to compression than other interocclusal recording material at various thickness. It exhibit minimal distortion during compression and give clinician the opportunity to make only minimal adjustments to the restorations that were delivered from the laboratory and avoid unnecessary use of chairtime, or repetition of some clinical and technical stages.

Comparative evaluation of bone in mandibular implant retained overdentures using delayed and immediate loading protocol: an in-vivo study.

The aim of the present study was to evaluate the changes in periimplant bone quality, crestal bone level and the implant stability (periotest) for mandibular implant retained overdentures with ball attachments using delayed and immediate loading protocols. Ten completely edentulous patients had two alpha bio dental implants placed in the anterior part of the mandible. The loading protocols for the patients was chosen randomly by drawing lots. Five patients were loaded under immediate loading protocols and other five following delayed. Crestal bone loss and bone quality were assessed around each implant. Periotest values were recorded for each implant at 3, 6 and 12 months after loading. Two implants were lost and were excluded from the study. However mean crestal bone loss around implants was 0.81 mm from the time of prosthetic loading to 12 months after prosthetic loading was seen and no significant result was found between the two groups for the crestal bone loss and the periotest values. Though the periotest value decreased (indicates increased stability) over the time period. The bone density changes were significant for both the groups at coronal level at all time intervals but at middle level significant only after 12 months of prosthetic loading, although individual variation was high. This study concluded that the changes in crestal bone level and periotest values were insignificant for the two groups. But the implant stability increased over the time and the crestal bone loss was evident with decreased rate over the period of time. There was wide individual variation for the bone density changes but overall increase in the density was seen.

A Cephalometric Study on the Relationship Between the Occlusal Plane, Ala-Tragus and Camper's Lines in Subjects with Angle's Class I, Class II and Class III Occlusion.

Considering the importance of the occlusal plane orientation in complete denture prostheses, a study was conducted on the relationship between this plane with ala-tragus and Camper's lines in soft tissue among individuals with class I, class II and class III occlusion. The aim of the present study was to define the best soft tissue index by which the location and inclination of the occlusal plane in complete dentures could be established. A total of 60 subjects were selected for the study. Lateral cephalograms of these subjects were obtained. Tracings and analysis was done to confirm to the skeletal relationship of subjects to be class I (normal), class II (prognathic maxilla) and class III (retrognathic maxilla). 20 Subjects of each group were screened for further analysis. Radiopaque markers were attached to the intended points on soft tissue and then standard lateral cephalograms were obtained from each subject. The angles between the following lines were measured: Occlusal line, Camper's line (ala-porion), AT1 (ala-superior border of tragus), AT2 (ala-mid-tragus) and AT3 (ala-inferior border of tragus). The mean values and standard deviations were calculated for all the groups. The mean values calculated were subjected to repeated ANOVA test and significance was evaluated. Comparison of the results by the ANOVA test exhibited a significant difference. In class I subjects, it was evaluated that in 75 % individuals, the posterior reference point was found to be the mid-tragus; of class II subjects, in 60 % individuals, the posterior reference point was found to be the mid-tragus; and of class III subjects, in 75 % individuals, the posterior reference point was found to be the inferior border of tragus.

Combined soft and hard tissue augmentation for a localized alveolar ridge defect.

Ideal alveolar ridge width and height allows placement of a natural appearing pontic, which provides maintenance of a plaque-free environment. The contour of a partially edentulous ridge should be thoroughly evaluated before a fixed partial denture is undertaken. Localized alveolar ridge defect refers to a volumetric deficit of the limited extent of bone and soft-tissue within the alveolar process. These ridge defects can be corrected by hard tissue and/or soft-tissue augmentation. A 30-year-old male patient was referred to the Department of Periodontology for correction of Seibert's Class III ridge defect in the lower anterior region. Granulation tissue/connective tissue present at the base of the defect was removed after elevation of full thickness flap. MucoMatrixX, an animal derived, collagen based soft-tissue graft was sutured to the labial flap and bone graft was placed into the defect. If a soft-tissue graft material could be used to replace the palatal grafts, then all the possible complications associated with donor site would be eliminated and above all periodontal plastic surgery and ridge augmentation would be better accepted by patients.