The International Journal of Prosthodontics, 05/2008

Purpose: This article presents a regenerative technique, morphogenic bone splitting (MBS), which overcomes the limitations associated with expansion techniques described to date. Materials and Methods: The authors propose a method whereby the bone-mucosa-gingival complex (BMGC) is displaced in its entirety, establishing a new focus for a secondary hinge located in the coronal reaches of the osteotomy. Depending on clinical needs, this approach modifies or eliminates the facially inclined hinge displacement characteristic of ridge expansion techniques. By exploiting the inherent capacity for second intention healing, the regenerative MBS technique avoids the use of graft material, membranes, or mechanical devices. It effectively harnesses the intrinsic regenerative capabilities of the treated site. Results and Conclusions: The MBS technique is performed in a single operation. By permitting the insertion of implants of an appropriate size in the optimum position for esthetic and functional requirements, it achieves the desired 3-dimensional reshaping of the BMGC and thereby restores the anatomy of the implant site. This reshaping includes: root prominences, keratinized gingiva, papillae, fornix, and the mucogingival junction. In addition to these esthetically significant issues, it permits implants to be placed at a functionally favorable axial inclination.

The aim of this study was to investigate the marginal fit of posterior fixed partial dentures (FPDs) made with 2 computer-aided design/computer-assisted manufacture systems-Procera Bridge Zirconia (Nobel Biocare) and Lava AllCeramic System (3M ESPE)-and to analyze the differences between abutments and between buccal and lingual surfaces. Twenty standardized specimens were prepared to receive posterior 3-unit FPDs. FPDs were fabricated according to the manufacturer's instructions. A scanning microscope (JSM-6400, JEOL) with a magnification of 1,0003 was used for measurements. Three-way analysis of variance showed significant differences (P .001) in marginal adaptation between the ceramic groups. Procera Bridge Zirconia showed the lowest discrepancies (26 ± 19 µm). No significant differences were observed between abutments and surfaces, and no significant interaction was observed among the ceramic system, abutments, and surfaces. The accuracy of fit achieved by both zirconia systems was within the range of clinical acceptability, with Procera Bridge Zirconia showing the best marginal fit.

Purpose: To present long-term clinical and radiographic data on single-implant treatment in the anterior maxilla and to compare these results with comparable data of central implants supporting fixed prostheses in the edentulous maxilla. Materials and Methods: A total of 38 patients consecutively restored with 47 single-implant crowns in the anterior maxilla were included in the single-implant (study) group. The implants in the edentulous group (control) were included by randomly selecting one of the central implants (closest to midline) from 76 consecutively treated edentulous patients. Mean age was 25.4 years (SD: 10.0) and 60.1 years (SD: 11.6) at inclusion (P .001) for the study and control groups, respectively. Clinical and radiographic data were retrospectively retrieved from files holding up to 15 years of function in both groups. Results: No implants in the study group were lost (cumulative success rate: 100%), while 3 implants in the control group were lost (cumulative success rate: 95.4%). Ten single crowns were replaced (15-year cumulative survival rate: 77.0%), and the study group showed more mucosal problems and fistulas compared to the implants in the control group (P .05). Loose screws were a common problem in the single-implant group during the first 5 years of function, but bone loss did not differ significantly between patients with stable and loose screws/fistulas (P > .05) or between study and control implants after 15 years (P > .05). Conclusions: There is an obvious difference between the survival of the implants (100%) and original implant crowns (77%) in the study group. The present early single-implant restorations showed significantly more mechanical/fistula problems compared to central implants in the edentulous maxilla (P .05), but bone response was similar for both groups during 15 years of follow-up. Bone loss was not affected by the level of the implant head in relation to the cementoenamel junction of adjacent teeth, nor was it affected by mechanical or mucosal problems or persistent fistulas of the single implants during the entire follow-up period.

This study aimed to (1) devise a standardized method of polishing and finishing acrylic resins, (2) eliminate the variable linked to the single operator, and (3) guarantee the reproducibility of the conditions in which smoothness surface values are obtained for comparative purposes. Twenty acrylic resin samples were fabricated (Lucitone, Dentsply). Samples in group 1 were manually polished by a single experienced operator, while samples in group 2 were polished using an isoparallelometer. Surface roughness was measured for both groups with a ± 0.01-µm resolution profilometer (Mahr, GD25). Data analysis showed that mechanical polishing results in a more uniform surface quality. This preliminary investigation underscores the merits of a standardized method for polishing dental acrylic resins. This approach can eliminate the effect of human factors, thereby making it possible to assess and compare the inherent features of each polished dental material.

The fracture resistance of acrylic resin and metal-reinforced acrylic resin fixed implant-supported prosthesis cantilever arms to linear vertical compressive forces was determined. Ten superstructures of each type were secured on 5 evenly distributed implants. Force was applied to the cantilever arms 15 mm distal to the distal-most implant, and 2 tests were conducted on each sample. In each sample, fracture of the acrylic resin was noted at the distal-most implant; however, in the nonreinforced samples, the acrylic resin fractured off completely, leaving the implants unaffected. There was no significant difference between the mean fracture value of the nonreinforced samples (679 N) and reinforced samples (628 N).

Purpose: This study aimed to determine whether gender, age, and initial tooth hue impacted the effect of laser tooth whitening. Materials and Methods: Ninety-one subjects were enrolled in a laser tooth whitening study at Kaohsiung Medical University. Sensitivity was evaluated by asking the patients about any tooth sensitivity they experienced after the whitening procedures were performed. The LaserSmile tooth whitener, containing 35% hydrogen peroxide, was applied to the tooth surfaces of both arches from the central incisor to the second premolar, and the LaserSmile Twilite diode laser was applied to the same maxillary and mandibular teeth. After removal of the whitening gel, shade matching was immediately performed with the ShadeEye NCC Dental Chroma Meter. Patients were classified into the following groups: tetracycline stain, gender, age, and initial tooth hue. Only 5 of the 91 individuals had tetracycline staining. Results: The initial tooth shade and the amount of shade change showed no significant differences between female and male patients, but a significant difference was found between hue and age group. Conclusions: Teeth with hue A showed greater shade improvement than teeth with hue C and hue D. Whitening response was better in younger individuals, and gender was not a factor that affected the whitening response. Sensitivity is common during the whitening procedure but can be tolerated by the patients.

This study aimed to analyze changes in Dental Impact on Daily Living (DIDL) scores in patients who had no prosthesis, a nonfunctioning prosthesis, or an acrylic resin prosthesis after providing them with a telescopic crown-retained partial denture. DIDL scores were recorded in 98 patients prior to and 6 to 24 months after treatment. All DIDL scores (overall and dimension scores) increased significantly after treatment. Results were only slightly affected by gender and age. Patients with fewer teeth benefited more than those with more teeth. Within the limitations of this study, the results show that a telescopic crown-retained partial denture can improve patients' oral health-related quality of life.

This in vivo study investigated interexaminer reliability in the clinical measurement of L*C*h* values using a spectrophotometer (Shadepilot, DeguDent), which provides laminar measurement. Thirty incisors were measured by 3 trained clinicians. Intraclass correlation coefficient was used to assess reliability. Additionally, the range of differences between the measurements by all examiners for each subject was calculated to assess the clinical impact of the differences. Agreement was acceptable to excellent for all measurements. Additionally, the reliability of the measurement of L* and C* was excellent (all measurements 5). Laminar spectrophotometric measurement seems to be superior to punctiform measurement.

Purpose: To assess and compare prosthodontic treatment needs and the related manpower requirements using the normative and sociodental needs approaches for adult Koreans aged 30 to 64 years. Materials and Methods: Data were obtained from 1,029 30- to 64-year-old adults who were a subsample of the 2003 Korean National Oral Health Survey. Subjects were clinically examined for normative needs and interviewed using an oral health-related quality of life (OHRQoL) measure, the Oral Impacts on Daily Performance. Their oral health behaviors were also assessed. The sociodental approach includes impact-related needs, in which normative needs are integrated with OHRQoL, and propensity-related needs, in which oral health behaviors are used to determine appropriate treatments. Prosthodontic treatment needs and number of clinicians needed to treat those needs were estimated using normative needs, impact-related needs, and propensity-related needs. Results: Compared to normative needs, significant decreases of 74.1% to 78.5% were found for prosthodontic treatment needs using impact-related needs and propensity-related needs, respectively. Differences in manpower requirements to deal with prosthodontic treatment were large; per 100,000 people, 86.5 dental clinicians would be needed using normative needs, compared to 22.4 clinicians using impact-related needs and 18.6 clinicians using propensity-related needs. Conclusions: The sociodental approach for assessing dental needs for prosthodontic treatment indicated much lower levels of treatment needs than the normative approach. The sociodental approach should be applied to dental workforce planning.

Purpose: This study aimed to investigate the electrochemical behavior of commercially pure titanium (grade II) coupled with type IV gold alloy and nickel-chromium alloy at different surface area ratios in 3 different electrolytes. Materials and Methods: Titanium was coupled with gold (Ti/Au) and nickel-chromium (Ti/Ni-Cr). For each couple, 9 surface area ratios between titanium and gold or nickel-chromium were prepared. The electrolytes used were 1% lactic acid, tryptic soy broth media, and Streptococcus mutans culture supernatant. The corrosion polarization curves were obtained, and average values of corrosion potential and corrosion current density were calculated. Results: Both Ti/Au and Ti/Ni-Cr were affected by surface area ratios and different electrolytes, showing the least corrosion rate when the ratio was 1:1 and when the lactic acid was used as an electrolyte. Conclusions: The greater the difference in surface area between titanium and restorative materials, the more corrosive behavior the materials show. The existence of bacteria such as S mutans may aggravate corrosive behavior between different metals.

Purpose: The aim of this study was to investigate bony changes around selectively overloaded implants in dogs. Materials and Methods: Twelve adult male beagles were used: 4 animals each for control, 4-week-load, and 12-week-load groups. Three implants were placed on the right side of each of the 12 animals and the time point designated as the study's baseline. Superstructures were then fabricated and attached only in the 2 implant-loaded groups 12 and 20 weeks following implant placement. Each lower distal implant was then fit with a cantilever-type superstructure extending in a mesial direction so as to be able to generate a controlled overload. The mesial and central implants were attached via superstructures equipped with a stainless steel screw, which could be tightened to create a controlled overload force. The force was induced by a controlled static 250-µm submerging of the cantilever of the distal implant. After 24 weeks, tissue specimens including implants were evaluated histologically and histomorphometrically. Results: Numerous fluorescence-labeled bone areas were noted in the 4-week-load group, showing a high remodeling activity. Marginal bone loss was significantly greater in the 12-week-load group than in the 4-week-load group. The ratio of fluorescence-labeled bone area in the inner thread region was significantly higher in the 4-week-load group than in the 12-week-load group. Conclusions: These findings demonstrate that static overload-induced forces can elicit changes in peri-implant bone in experimental animals.

The aim of this study was to evaluate the stress distribution at the marginal edge of metal-free crowns using 2 different materials (ceramic and hybrid composite) and 4 different preparation designs (knife edge, chamfer, heavy chamfer, rounded shoulder). All marginal preparation designs for hybrid composite crowns showed lower compression and tensile stress than the ceramic crowns. The rounded shoulder preparation provided more even stress distribution than the knife-edge preparation. Heavy chamfer was an acceptable preparation design for ceramic crowns. The chamfer preparation was preferred for hybrid composite crown.