Kenneth S. Kurtz

Effect of sandblasting and silicoating on bond strength of polymer-glass composite to cast titanium

STATEMENT OF PROBLEM There is little information regarding the mechanical and chemical retention of polymer-glass composite to cast titanium. PURPOSE This study examined whether sandblasting in conjunction with silicoating improves the bond strength of the polymer-glass composite to cast titanium. MATERIALS AND METHODS Disk patterns (10 mm in diameter, 2.5 mm thick) were cast with commercially pure titanium (CP Ti) and Type IV gold alloy. Three pretreatments were applied: 50 microm Al(2)O(3) sandblasting (50 SB), 250 microm Al(2)O(3) sandblasting (250 SB), and 600-grit SiC paper polishing (600 SiC). After surface preparation, the Siloc system (silicoating) was applied on the disks. The 50 SB specimens without Siloc system were also prepared as controls. Then sticky tape with a circular hole (4.76 mm diameter) was placed onto the disk to define the bonding area. Artglass (polymer-glass) opaque, dentin, and enamel composites were applied using Teflon matrices and then light-polymerized. Shear bond strength (n = 8) was determined at a crosshead speed of 5 mm/min. Results were analyzed statistically with 2-way ANOVA and the Tukey-Kramer test (alpha=.05). RESULTS The Siloc system significantly (P <.05) improved the mean shear bond strength of Artglass to both metals in the 50 SB specimens. Statistical differences (P <.05) in shear bond strength were found among surface treatments for the silicoated CP Ti specimens, in which 250 SB specimens yielded the greatest bond strength. The Type IV specimens treated with Siloc system showed no significant differences in shear bond strength between the 50 SB and the 250 SB specimens. CONCLUSION Sandblasting with coarser alumina particles in conjunction with silicoating significantly enhanced bond strength of polymer-glass composite to cast titanium.

Laser surface treatment to improve mechanical properties of cast titanium

OBJECTIVE The aim of this study was to investigate the effect of laser surface treatment on the mechanical properties of cast titanium and to compare with those of the Co-Cr alloy. METHODS Dumbbell-shaped cast specimens were prepared for commercially pure titanium (grade 2) and Co-Cr alloy. The cast titanium specimens were laser-treated on the surface using a dental Nd:YAG laser machine at 240 V and 300 V. After laser treatment, tensile testing was conducted to obtain the tensile strength, percent elongation and modulus of elasticity. The hardness depth profile was made from the cast subsurface (25 microm) to 1500 microm in depth using the cross-sections of the cast rods with the same diameter as the dumbbell. The data were statistically analyzed by ANOVA/post hoc tests (p<0.05). RESULTS The highest tensile strength was obtained for the titanium specimens laser-treated with 300 V followed by the 240 V and the control specimens. The laser-treated titanium specimens with 300 V showed a tensile strength equivalent to the Co-Cr alloy. Although the highest modulus of elasticity was found for the specimens laser-treated with 240 V, there were no significant differences in elastic modulus among 240 V, 300 V and Co-Cr. The laser-treated groups showed significantly lower hardness at the subsurface of 25 microm and maintained their hardness until the depth of 400 microm. The hardness of the control group was very high at 25 microm depth, and dramatically decreased until the 200 microm depth. CONCLUSION The results of tensile testing and hardness depth-profiling indicated that the laser treatment significantly improved the mechanical properties of cast titanium by improving the surface integrity of the cast surface contamination.

Rehabilitation of children with ectodermal dysplasia. Part 2: an international consensus meeting.

A consensus meeting was arranged to provide an opportunity to discuss the residual nonconsensus questions following three rounds of a Delphi study. It was hoped that the nonagreements could be resolved to define a comprehensive protocol for the management of ectodermal dysplasia, particularly with respect to the use of dental implants in growing patients. An international panel of expert clinicians in pediatric dentistry, prosthodontics, and orthodontics was invited to be part of the Delphi study to develop agreement on clinical questions through a consensus of ideas. Each expert had been invited to form a study group or team within his or her home institution. As required by the Delphi protocol, a 90-part questionnaire was considered by the collaborating teams and progressed through three iterations with increasing agreement. This process is discussed in part 1 of the study. The residual nonconsensus questions, which represented 10% of the questionnaire, required collaborative interaction for resolution. The consensus meeting was held in London, England, over a 2-day period with support from Nobel Biocare and the British Dental Association.

A sectional stock tray system for making impressions

This article describes a sectional stock tray system developed by the authors for making preliminary impressions. It may be used not only for individual dental arches but also for patients with microstomia or constricted oral openings. This system allows many combinations of right and left tray sizes and forms to be assembled into a well-fitted anatomically-conforming tray in spite of individual anatomic discrepancies.

Rehabilitation of children with ectodermal dysplasia. Part 1: an international Delphi study.

PURPOSE An international Delphi study was undertaken to determine by consensus an agreed approach to the management of children with dental manifestations of ectodermal dysplasia, including the use of dental implants. This was done using a questionnaire developed by an interdisciplinary team. MATERIALS AND METHODS The Delphi study questionnaire was built around 19 areas of clinical relevance and included 90 items. Topic areas included dental disability; initial diagnosis; global disability; oral health aspects of dental treatment (orthodontics, hypodontia, anodontia, implants); and case studies of selected treatment options. Eleven teams from six countries contributed to three iterations of the questionnaire. An algorithm was designed to standardize analysis of the questionnaire answers, all of which were blinded to ensure anonymity. The second and third rounds of the questionnaire excluded previously agreed-upon items but included the responses to the questions from the earlier rounds. The nonconsensus items inquired about the use of radiographs at initial diagnosis; sedation of an uncooperative child; use of a pretreatment questionnaire; the age range for specific treatments (eg, dentures, orthodontics, implants); specific uses of implants (eg, partial prostheses, overdentures, cantilevered prostheses); and case study 2. The residual nonconsensus questions were subsequently discussed at a 2-day meeting. RESULTS Among the 90 questions and partial questions, there was progressive consensus, with agreements in rounds 1, 2, and 3 of 61%, 21%, and 8%, respectively. At the conclusion of round 3, there was 90% agreement and it was considered that the nonconsensus items required in-depth face-to-face discussion at a consensus meeting, which is described in part 2 of the study. CONCLUSION The Delphi study provided an opportunity to engage specialist teams in recognized centers to integrate their clinical knowledge and draw on published data to develop a consensus of evidence-based responses.

Interim Prosthetic Phase of Multidisciplinary Management of Cleidocranial Dysplasia: “The Bronx Approach”

This case report presents treatment of two patients with the usual characteristics of Cleidocranial Dysostosis. A multidisciplinary approach using the disciplines of prosthodontics, orthodontics, and oral surgery was effected. Exfoliation of the patients deciduous teeth and failure of permanent anterior tooth eruption led to emotional, social, and self-esteem issues in both patients. Due to the psychosocial issues confronting these two patients, esthetics was addressed prior to active intervention with orthodontics and after some surgical intervention. The use of two interim overdenture prostheses with magnetic retention is described.

Analysis of buccolingual dimensional changes of the extraction socket using the "ice cream cone" flapless grafting technique.

Multiple adjacent recession defects were treated in 32 patients using a coronally advanced flap (CAF) with or without a collagen matrix (CM). The percentage of root coverage was 81.49% ± 23.45% (58% complete root coverage) for CAF sites (control) and 93.25% ± 10.01% root coverage (72% complete root coverage) for CM plus CAF sites (test). The results achieved in the test group were significantly greater than in the control group, indicating that CM plus CAF is a suitable option for the treatment of multiple adjacent gingival recessions.

Effect of engaging abutment position in implant-borne, screw-retained three-unit fixed cantilevered prostheses.

PURPOSE To investigate the effects of internally connected engaging component position in screw-retained fixed cantilevered prostheses. MATERIALS AND METHODS Twenty-one three-unit fixed dental prostheses (FDPs) were cast in high-palladium alloy in three groups. In group A, engaging components were incorporated into the units away from the cantilevered segment; proximal units received nonengaging components. In group B, these positions were reversed. Control specimens were fabricated using all nonengaging components. Specimens were attached to internally connected 3.5 (diameter) × 13 mm (length) implants, torqued to 32 Ncm, and embedded into epoxy resin. Specimens were tested in cyclic fatigue with a 2 Hz sine wave and 0.1 min/max load ratio. Load amplitude started at 1.8 N and increased by 1.8 N every 60 cycles until fracture. Log-rank statistic, ANOVA, Spearmans correlation, and LIFETEST procedures were used to evaluate level of statistical significance within the results. RESULTS In the control group, the mean number of cycles to fracture was 31,205 ± 2639. Mean axial force at fracture was 932 ± 78 N. In group A, these numbers were 38,160 ± 4292 and 1138 ± 128 N, and in group B, 31,810 ± 3408 and 949 ± 101 N. Statistical significance levels for number of cycles to fracture were: Control versus group A, p = 0.0117, and groups A versus B, p = 0.0156 (statistically significant). Control versus group B, p = 0.357 (not statistically significant). Log-rank statistic for the survival curves is greater than would be expected by chance; there was a statistically significant difference between survival curves (p = 0.012). The location and mode of failure were noteworthy (always in the abutment screw). CONCLUSIONS The position of the engaging component had significant effects on the results. Within the limitations of this investigation, it can be concluded that using an engaging abutment in a screw-retained fixed cantilevered FDP provides a mechanical advantage, and engaging the implant furthest from the cantilever when designing a screw-retained cantilever FDP increased resistance to fracture of the distal abutment screw.

Clinical application of stress-breaking ball attachment for implant overdenture

PATIENT The patient was a 62-year-old partially edentulous woman with missing bilateral premolars and molars in the mandibular jaw. The patient selected implant supported-removable partial denture rehabilitation. Implants were placed bilaterally at the distal extension of the denture base in order to minimize denture displacement. The stress-breaking ball (SBB) attachment consists of a flat-top ball head male and O-ring rubber female. The female was covered by a silicone housing with three amounts of space to allow three kinds of settlement (0.3 mm, 0.5 mm, and 0.7 mm); they were selected by thickness or pressure displacement of the mucosa and occlusal force. After the healing period, the SBB attachments (0.3 mm) were placed on the implants, and the implant-supported removable partial denture was then conventionally fabricated. The delivered denture had sufficient retention and appropriate stress breaking. DISCUSSION The advantages of SBB attachments over conventional attachments are as follows: (1) they prevent the implant from excessive occlusal force, (2) they are ready-made, (3) they show appropriate retention, and (4) they can be easily mounted on the denture base. The disadvantages of these attachments are as follows: (1) they are approximately 1mm higher than conventional ball attachments and (2) the retentive force cannot be adjusted. CONCLUSION The use of a stress-breaking attachment for implant overdenture rehabilitation should be considered so that the occlusal force is equally distributed between the alveolar ridge and the implants.

Fabrication of fixed implant prostheses using function bite impression technique (FBI technique)

PATIENT The patient was partially edentulous, lacking both the first mandibular molars. The FBI and the conventional impression technique were used for the fabrication of implant-fixed prosthesis replacing the right and left molars, respectively. In the FBI technique, the definitive impression was made under occlusal force and functionally generated path (FGP) recording at the same time. The right and left occlusal contact areas were compared after completing the implant-fixed prosthesis rehabilitation. DISCUSSION It has been suggested that accuracy of the impression and maxillomandibular registration is necessary to ensure a satisfactory long-term clinical outcome. The transfer of the exact position of the implants to the working cast is even more important because implants lack the mobility of natural teeth. There are displacement differences between implants and natural teeth under occlusal force. The FBI technique may compensate for this difference in accuracy. CONCLUSION Using the FBI technique, a precise prosthesis could be produced by completing simultaneously the maxillomandibular registration, impression and FGP.