Integrating a complete denture digital workflow with polished surface registration: A single-procedure clinical protocol.

Intraoral digital scanning of edentulous arches has provided the dental profession with the ability to obtain genuinely mucostatic impressions. The drawback, because of the omission of border molding procedures, has been underextended flanges which might affect the retention and stability of the definitive prosthesis. A technique for combining the concept of registering the polished surfaces with a functional impression material and the intraoral digital mucostatic scanning workflow is described.

Retentive force variations in three polyamide and a polyetheretherketone denture attachments for implant-supported overdentures: An in vitro study.

STATEMENT OF PROBLEM: The loss in the retentive capability of implant-supported overdenture attachments has been related to the wear of the retentive inserts. Wear of the abutment coating material when following the replacement period for the retentive inserts requires investigation. PURPOSE: The purpose of this in vitro study was to compare the changes in retentive force of 3 polyamide and a polyetheretherketone denture attachments under repeated insertion and removal cycles in wet conditions while following their manufacturers' replacement time recommendations. MATERIAL AND METHODS: Four different denture attachments (LOCKiT, OT-Equator, Ball attachment, and Novaloc) with their retentive inserts were tested. Four implants were embedded into individual acrylic resin blocks, and 10 abutments for each attachment were used. Forty metal housings with their retentive inserts were attached to polyamide screws with autopolymerizing acrylic resin. A customized universal testing machine was used to simulate insertion and removal cycles. The specimens were mounted on a second universal testing machine at 0, 540, 2700, and 5400 cycles, and the maximum retentive force was recorded. The retentive inserts for LOCKiT (light retention), OT-Equator (soft retention), and Ball attachment (soft retention) were replaced every 540 cycles, while the Novaloc (medium retention) attachments were never replaced. All the abutments were weighed with a precision scale at 0, 2700, and 5400 cycles. The surface of every abutment was examined under a stereomicroscope at ×10 magnification. Data were analyzed with descriptive statistics. Two-way repeated measures ANOVA was used to compare the mean retentive force and mean abutment mass of all groups and time evaluation points. Bonferroni corrections were made to adjust for multiple tests (α=.05). RESULTS: The mean retention loss for LOCKiT was 12.6% after 6 months and 45.0% after 5 years of simulated use. The mean retention loss for OT-Equator was 16.0% after 6 months and 50.1% after 5 years of simulated use. The mean retention loss for Ball attachment was 15.3% after 6 months and 39.1% after 5 years of simulated use. The mean retention loss for Novaloc was 31.0% after 6 months and 59.1% after 5 years of simulated use. The mean abutment mass difference was statistically significant (P<.05) for LOCKiT and Ball attachment but not statistically significant (P>.05) for OT-Equator and Novaloc at baseline, 2.5 years, and 5 years. CONCLUSIONS: All tested attachments recorded retention loss under the experimental conditions, even when their manufacturers' recommendations for replacement time for the retentive inserts were followed. Patients should be aware that implant abutments should be replaced after a recommended period since their surfaces also change over time.

Evaluating temperature increase during the polymerization of dental acrylic resin materials used for the direct fabrication of anterior deprogramming devices.

STATEMENT OF PROBLEM: The polymerization of acrylic resin materials used for the direct fabrication of anterior deprogramming devices results in a temperature increase because of the exothermic reaction. This heat release might cause thermal trauma to the pulp, compromising the tooth's vitality. PURPOSE: The purpose of this in vitro study was to compare the temperature increase and the timing of the maximum temperature recording obtained inside the pulp chamber of a maxillary central incisor during the polymerization of different resins materials used for the direct fabrication of anterior deprogramming devices. MATERIAL AND METHODS: The exothermic reaction was examined during the polymerization of 4 different polymethyl methacrylate resin products: Pattern Resin LS; GC America, DuraLay inlay pattern resin; Reliance Dental, Kallocryl CPGM red; Speiko, and mega-Model Resin NF; Megadental. A polymeric matrix was fabricated to simulate the anterior deprogramming device. A freshly extracted intact maxillary central incisor was fixed in an acrylic resin mold, and a thermal probe was inserted into the pulp chamber to transmit the temperature recordings. The resin materials were mixed as per the manufacturer's instructions and an equal volume of each was inserted into the plastic matrix, which was then positioned on the tooth. The temperature increase and the time needed to obtain the maximum temperature were recorded. The temperature and time recordings were performed initially for the intact tooth and repeated after the tooth was prepared for a metal-ceramic restoration. The data were analyzed with descriptive statistics, 1-way analysis of variance, and the Tukey Honestly Significant Difference tests (α=.05). RESULTS: In accordance with the 1-way ANOVA, there was a statistically significant difference both in temperature increase (F [7,72] = 3.72, P=.002) and in the recorded time (F [7,72] = 160.80, P<.001). The mean temperature inside the pulp chamber ranged from 40.1 °C for the Pattern Resin LS to 41.4 °C for the DuraLay inlay pattern resin material. The mean time recordings ranged from 133 seconds for the Kallocryl CPGM red material to 266 seconds for the DuraLay inlay pattern resin material. CONCLUSIONS: The Pattern Resin LS revealed the lowest exothermic reaction (P<.05) when compared with the other materials tested in this study, whereas Kallocryl CPGM red had the shortest time increase without being statistically significantly different.

Comparative Study of Dimensional Stability and Detail Reproduction of Reformulated and Nonreformulated Elastomeric Impression Materials.

PURPOSE: To evaluate the dimensional stability and the detail reproduction of five current elastomeric impression materials in vitro. MATERIALS AND METHODS: The materials examined were: 3 different polyether impression materials, a vinyl polysiloxane impression material, and a vinyl polyether silicone impression material. All impression materials were of a medium viscosity. One stainless steel die was fabricated according to the ANSI/ADA specification no.19 criteria. Twenty impressions of this die were made for each material. Dimensional accuracy and surface detail were evaluated 24 hours after making the impressions using a measuring microscope. The data were analyzed using Welch's analysis of variance, Games-Howell Post-Hoc, and the Pearson's chi-square tests (α = 0.05). RESULTS: Statistical differences were observed in the mean percent dimensional stability (F [4,47] = 39, p < 0.001) of the tested impression materials. The highest dimensional change was recorded for the vinyl polysiloxane impression material, with a mean percent value of -0.09 ± 0.02% (p < 0.001). The lowest dimensional change was recorded for the Monophase polyether material with a mean percent value of -0.03 ± 0.01% (p < 0.038). The best surface detail reproduction results were obtained using the Monophase polyether material (90% acceptable impressions), with no significant differences (χ² [4] = 3.86, p = 0.483) observed between the Monophase and the rest impression materials. CONCLUSIONS: All materials exhibited acceptable dimensional stability, well below the ANSI/ADA specification no.19 standard of ≤0.5% dimensional change. All impression materials demonstrated acceptable surface detail reproduction with no significant differences between them.

Comparative Study of Acceptance and Adaptation to New Complete Dentures, Using Two Construction Protocols.

PURPOSE: To validate patients' acceptance and adaptation to new complete dentures, fabricated using two construction protocols. Evaluation was achieved by means of two psychometric questionnaires and registration of total number of sore spots. MATERIALS AND METHODS: Twenty complete denture wearers, who sought replacement dentures because of complaints (material degradation or unsatisfactory repaired fracture) associated with them, were selected according to specific inclusion criteria. The denture construction protocols were randomly assigned to the study participants. Ten participants received complete dentures using a duplication construction protocol with a bilateral balanced occlusal (BBO) scheme (duplicate complete denture group); ten participants received complete dentures using a traditional construction protocol with BBO (traditional complete denture group). All study participants completed the Complete Denture Satisfaction and the Oral Health Impact Profile-20 (OHIP-20) questionnaires before they received the new complete dentures (pretreatment) and at 3 and 6 months post-treatment. At the initial adaptation/adjustment visits, the location and number of sore spots were identified. Statistical analysis was performed to evaluate differences between groups and within each group pre- and post-treatment. RESULTS: Denture satisfaction and oral health related quality of life scores were independent of the complete denture construction protocol. Within the traditional complete denture group there was a statistically significant increase in denture satisfaction and equivalent decrease (improvement) in OHIP-20 scores between pre- and post-treatment (both at 3-month and 6-month visits). This finding was consistent for OHIP-20 scores within the duplicate complete denture group, but not for denture satisfaction, which was not statistically significant. The total number of recorded sore spots was approximately double for the traditional complete denture group compared to the duplicate complete denture group. CONCLUSIONS: According to the results of the study, patients' overall acceptance of their newly constructed complete dentures improved significantly for both groups (traditional and duplication construction protocols). Study participants adapted dissimilarly to their newly constructed complete dentures regarding comfort, as assessed by the total number of sore spots, although the recorded mean number of initial adaptation/adjustment visits was equal.

Exploring Adaptation and Satisfaction in Copied Complete Dentures Regarding Two Different Occlusal Schemes

PURPOSE: To compare patient adaptation to and satisfaction with new complete dentures fabricated with a duplication construction protocol (DCP) using two different occlusal schemes, bilateral balanced (BBO) and lingualized (LO). MATERIALS AND METHODS: Twenty complete denture wearers who received replacement DCP dentures participated in this study. Ten participants received complete dentures with a BBO scheme, and the other 10 received DCP dentures with an LO scheme. All of them evaluated their prostheses subjectively through the Oral Health Impact Profile-20 (OHIP-20) and the Complete Denture Satisfaction (CDS) questionnaires before treatment and at 3- and 6-month posttreatment intervals. The new prostheses were also normatively evaluated by recording the location and number of sore spots present at the scheduled early adjustment visits. Data were analyzed with nonparametric tests to identify differences in patient responses between groups and within each group at each evaluation interval point (α = .05). RESULTS: The within-group comparisons revealed statistically significant improvement for both denture groups (P < .05), while the between-group comparisons did not record statistically significant differences at the overall evaluation period (P > .05). Significant within-group differences were recorded in the pain, functional limitation, and psychologic disability domains of the OHIP-20 questionnaire and the comfort, esthetics, and stability domains of the CDS questionnaire. CONCLUSION: The patients' adaptation to and satisfaction with newly constructed DCP dentures improved significantly for both BBO and LO denture groups throughout the evaluation period. The mean number of early adjustment visits was equal for both the BBO and LO denture groups.

In vitro assessment of retention and resistance failure loads of complete coverage restorations made for anterior maxillary teeth restored with two different cast post and core designs.

BACKGROUND: The purpose of this in vitrostudy was to evaluate the retention and resistance form of complete coverage restorations supported by two different cast post and core designs. MATERIAL AND METHODS: Forty extracted maxillary central incisors were randomly divided into four groups of 10 specimens each (namely A, B, C and D). All specimens were endodontically treated and a uniform post space of 9mm was created. All prepared teeth had a 360o chamfer ferrule of 2mm in axial height measured 0.5mm coronally from the cementoenamel junction (CEJ) and an axial wall thickness of 1.5 mm. Specimens in groups A and C received cast post and cores with the standardized core design, where the core ended at the coronal part of the ferrule, while specimens in groups B and D received cores that were encircling the ferrule. Cemented complete coverage restorations in groups A and B underwent tensile load stress, while the restorations in groups C and D underwent compressive load stress until failure. RESULTS: Teeth in group A exhibited a mean failure load of 326.14±83.67 N under tension, while teeth in group B exhibited a mean failure load of 332.79±80.38 N (p=0.858). Teeth in group C recorded a mean failure load of 1042.81±205.07 N, and in group D a mean failure load of 875.15±167.64 N (p=0.061) under compression was registered. CONCLUSIONS: The standard cast post and core design with a 2 mm of ferrule height offers superior resistance, although not statistically significant (p=0.061), when compared to the core design encircling the axial wall ferrule. Both cast post and core designs offer equal retention. However, different failure modes of decementation were noted. Key words:Endodontically treated teeth, Post-and-core technique, Endodontic-post, Decementation, Root fracture, Ferrule effect.

In vitro investigation of the impact of remaining tooth structure on the tensile failure loads of overdenture copings.

BACKGROUND: The purpose of this in vitro study was to evaluate the impact of the remaining tooth structure on the retention of overdenture cast metal copings. MATERIAL AND METHODS: A freshly extracted intact mandibular human canine (length 25 mm) was selected and endodontically treated. An incisal reduction of 4 mm with no ferrule preparation was performed and a post space of 12 mm was created. By using polyvinyl siloxane duplication material and autopolymerizing polymethylmethacrylate resin, ten resin teeth analogs (control group) were obtained. A second set of ten resin teeth analogs (group 1) was created by preparing on the original natural tooth a 360o ferrule design of 1 mm in height and by using the same procedural technique. The canine was further reduced by an additional 1 mm, resulting in a ferrule of 2 mm in height, measured from the initial incisal reduction, thus a third set of ten resin teeth analogs (group 2) was created. For every tooth analog in all groups a dome-shaped metal coping was cast and luted with a glass ionomer cement. All specimens were subjected to tensile load testing until decementation occurred. RESULTS: The specimens in the control group exhibited a mean failure load of 87.21 ± 18.26 N, while the 1 mm ferrule group recorded a higher mean failure load of 125.43 ± 8.79 N and the 2 mm ferrule group recorded the highest mean failure load of 146.12 ± 23.38 N. One-way ANOVA revealed significant differences (F= 28.04, p<0.001) in the tensile failure loads between all of the groups being tested. CONCLUSIONS: The metal copings with a 2 mm ferrule design exhibited the highest retention values, followed by the 1 mm ferrule and the no ferrule design, with the differences among them being statistically significant. Key words:Ferrule effect, In vitro study, Metal copings, Overdenture, Tensile stress.

The Effect of Clenching and Occlusal Instability on Body Weight Distribution, Assessed by a Postural Platform.

The purpose of this research project was to investigate whether or not clenching and occlusal instability of Angle's Class I malocclusion have an effect on body weight distribution in healthy adult subjects. Twenty adults (fourteen males and six females, ages 27-40, mean age 31.7 years, SD 3.32) were included in this study. The MatScan (Tekscan Inc., Boston, MA) system was used to measure the body weight distribution changes of the subjects. Four body weight distribution measurements were taken for each subject while (1) the mandible was in the rest position (no tooth contact) (RES), (2) subject was clenching (maximum intercuspation of the teeth with heavy occlusal forces) (CL), (3) subject was clenching on the right side (with 1 mm disocclusion on the left side) (CLR), and (4) subject was clenching on the left side (with 1 mm disocclusion on the right side) (CLL). The lateral and the anteroposterior body weight distribution changes during the different clenching conditions (both sides, right, and left) were compared to those at which the mandible was at the rest position. The statistical significance of these results was tested with a Chi-Squared test (p<0.05). Based on the findings of the present study it was concluded that clenching and occlusal instability are associated with lateral body weight distribution changes.

Nonsurgical management of soft tissue deficiencies for anterior single implant-supported restorations: a clinical report.

Periodontal surgical procedures may not always offer a predictable level of success in the reproduction of a natural gingival architecture. Two different nonsurgical approaches are described for the management of soft tissue deficiencies in anterior implant-supported restorations. Clinically acceptable esthetic outcomes of anterior implant restorations can be achieved by using zirconium custom abutments and gingiva-colored dental porcelain.