Comparison of Marginal Bone Levels Around Tissue-Level Implants with Platform-Matched and Bone-Level Implants with Platform-Switching Connections: 1-Year Results of a Prospective Cohort Study with a Split-Mouth Design.

PURPOSE: This clinical study was conducted to compare the influence of a platform-switched bone-level implant and a platform-matched tissue-level implant on marginal bone loss during the first year after loading. MATERIALS AND METHODS: Edentulous subjects who applied for two-implant-retained mandibular overdentures and showing sufficient bone volume for implants with 4.3-mm diameter and 12-mm length were enrolled. For standardization reasons, all subjects received a platform-matched tissue-level implant and a platform-switched bone-level implant in the anterior mandible. Since implants from the same manufacturer were used, both implants had identical implant thread designs and surface properties. All subjects received two-implant-retained mandibular overdentures with opposing maxillary complete dentures, and the implants were loaded after 6 weeks. Marginal bone loss was monitored via panoramic radiographs obtained immediately after loading and at the 6- and 12-month recalls after implant loading, and periodontal parameters, such as pocket probing depths, Plaque Index scores, and bleeding on probing, were also measured and recorded. RESULTS: Twenty-six patients received 26 bone-level and 26 tissue-level implants. No statistically significant differences were detected between the bone loss of the two groups for all the measurements (P > .05). Additionally, no significant difference was detected between the measured periodontal parameters of the two groups (P > .05). CONCLUSION: Within the limitations of this prospective clinical study with a follow-up time of 12 months, it can be concluded that the platform-switching bone-level design and the platform-matching tissue-level design show similar bone loss in the anterior edentulous mandible.

In vitro comparison of trueness of 10 intraoral scanners for implant-supported complete-arch fixed dental prostheses.

STATEMENT OF PROBLEM: Digital scanning systems have become popular, but whether these systems are adequate for complete-arch implant-supported fixed dental prostheses is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the trueness of 10 different dental intraoral scanners. MATERIAL AND METHODS: Six implant analogs were installed, and an edentulous mandibular model composed of scannable Type 4 gypsum was scanned with 10 different intraoral scanners (3D Progress, Omnicam, Bluecam, Apollo DI, Planscan, E4D Tech, TRIOS MonoColor Cart, TRIOS Color Cart, TRIOS Color Pod, Lythos), 10 times each after the scan body was placed on the implant abutments. The data obtained were then converted into standard tessellation language format. For the control group, the gypsum model was scanned with an industrial scanner (ATOS Core 80). For trueness, the dental and industrial scanning data packs were analyzed with 3D comparison software. Statistical analyses were performed by using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: When ranked according to their surface superimposition values, the Color POD, Omnicam, Apollo DI, Color Cart, MonoColor Cart, and Bluecam scanners were found within the range of 31 to 45 µm. This group was followed by E4D, 3D Progress, Lythos, and Planscan, which were found within the range of 82 to 344 µm according to the same criteria. CONCLUSIONS: Some of the digital scanners had the necessary performance for the fabrication of complete-arch implant-supported fixed dental prostheses. However, the possibility of data loss producing artifacts should be considered.

Clinical Comparison of Screw-Retained and Screwless Morse Taper Implant-Abutment Connections: One-year Postloading Results.

PURPOSE: The purpose of this study was to clinically evaluate the screwless Morse taper implant-abutment connection type, in which the retention screw is totally eliminated, in terms of stability, success, periodontal parameters, and marginal bone levels after 1 year of function by comparing it with a passive fit internal implant-abutment connection, wherein a space exists between the matching components. MATERIALS AND METHODS: Each edentulous subject received an implant with a screwless Morse taper connection (MT) in the left canine area of the mandible and an implant with a screw-retained implant-abutment connection (SR) in the right canine area of the mandible. All implants were loaded 6 weeks later. All cases were restored with a cemented bar-retained mandibular overdenture opposing a maxillary complete denture. Clinical recalls at 6 months and 12 months postloading were scheduled and the MT and SR implants were compared in terms of success, survival, primary and secondary implant stability, marginal bone loss, soft tissue response, and mechanical complications. The results were statistically analyzed. RESULTS: A total of 20 subjects were included (10 females, 10 males; average age: 61.60 years) and a total of 40 implants were inserted. No implant failure or technical problem was detected for either MT or SR implants. Marginal bone loss around MT and SR implants did not show any significant differences at 6 weeks after surgery (time of loading) or at 6 months or 12 months postloading (P > .05). Periodontal parameters such as gingival index and probing pocket depth of MT and SR implants likewise did not differ significantly at 6 months and 12 months postloading (P > .05). Primary stability values of MT and SR implants did not differ significantly when measured with the insertion torque device (mean of 68.10 Ncm for MT and 64.20 Ncm for SR implants; P = .564), nor when measured with the electronic percussive testing device (mean of -5.30 for the MT and -5.35 for the SR implants; P = .398). However, MT implants showed lower stability at the time of loading (6 weeks) and 6 months postloading (P = .037 and P = .003, respectively). Stability values did not show any significant differences 12 months postloading (P > .05). CONCLUSIONS: Within the limitations of this clinical study, it can be concluded that implants with screwless Morse taper and passive fit internal connections show comparable technical and biologic results after 1 year of function.

In vitro comparison of the retentive properties of ball and locator attachments for implant overdentures.

PURPOSE: To compare the retentive properties of ball and locator attachments during 5,000 insertion-separation cycles, corresponding to approximately 4.5 years of clinical use. MATERIALS AND METHODS: Four dental implants (diameter, 3.8 mm; length, 12 mm) were inserted into the prepared beds of two polyethylene blocks. Twenty acrylic prosthetic components were fabricated and connected to the ball and locator abutments. Tensile force was applied to the prosthetic components until the attachments were separated from the abutments. All samples were subjected to 5,000 insertion-separation cycles. Retention forces were measured after 10, 100, 200, 300, 400, 500, 1,000, 1,500, 2,000, 3,000, 4,000, and 5,000 insertion-separation cycles. Additionally, the wear of the attachments was measured using scanning electron microscopy. Data were analyzed to determine statistical equivalence among the two different attachments using the Student t test procedure and the Mann-Whitney U test procedure (α = .05). RESULTS: Ball attachments showed significant retention loss after 100, 200, 400, 500, 1,500, and 4,000 cycles, and the locator attachments showed significant retention loss after 100, 200, 300, 500, and 3,000 cycles as compared with the previous cycle (P < .05). Retention loss after 5,000 cycles was detected significantly more often for ball attachments than for locator attachments (P = .049). No significant difference was detected between the retention losses of the two attachment systems during the other cycles as compared with the initial retention values (P > .05). No significant difference was detected between the wear on the two attachment systems after 5,000 cycles (P > .05). CONCLUSION: Both attachment systems showed decreased retentive forces after 5,000 insertion-separation cycles. However, after 5,000 insertion-separation cycles, locator attachments showed better retentive properties than ball attachments.

The effect of urea on the corrosion behavior of different dental alloys.

OBJECTIVE: Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys. MATERIALS AND METHODS: Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations. RESULTS: Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials. CONCLUSION: The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.

The efficacy of a topical gel with triester glycerol oxide in denture-related mucosal injuries.

OBJECTIVE: The efficacy of a topical gel with triester glycerol oxide for treating ulcerations related to new complete dentures was studied and compared with a placebo gel. MATERIALS AND METHODS: Fifty edentulous patients were enrolled in this double-blind clinical study. All subjects received new maxillary and mandibular complete dentures and were recalled 1, 3 and 7 days after denture placement. Twenty-five subjects received topical gel with triester glycerol oxide (TGO), and 25 subjects received topical gel without TGO. At each visit, pain and discomfort with the new dentures was assessed, and at the last visit, healing of ulcerations was also graded by a clinician. Subjects also graded the gel's taste, smell and ease of use. RESULTS: Specifically, there was no statistically significant difference in ulcer healing (p > 0.05), ratings of smell, taste and ease of use (p > 0.05) or pain and discomfort scores (p > 0.05). However, within-group differences were observed in pain and discomfort scores between follow-up sessions (p = 0.01 for all comparisons). CONCLUSION: Clinically, TGO gel is not effective in the treatment of mucosal injuries occurring following placement of complete dentures.

Three-year radiologic follow-up of marginal bone loss around titanium dioxide grit-blasted dental implants with and without fluoride treatment.

PURPOSE: This study was conducted to evaluate the influence of fluoride-treated, titanium dioxide grit-blasted implant surfaces on marginal bone levels through radiography at 3 years after functional loading and to determine whether a correlation exists between primary stability and marginal bone levels of implants. MATERIALS AND METHODS: Edentulous patients who sought two-implant-retained mandibular overdentures and were available for follow-up were included. Each patient received two implants in the mandible; one implant received fluoride treatment and the other did not. To determine primary stability of the dental implants, resonance frequency analysis was performed at the time of implant placement. Panoramic radiographs were obtained preoperatively, at the time of overdenture connection, and at 6-month and 1- , 2-, and 3-year follow-up examinations. RESULTS: Fifty-two edentulous patients with a mean age of 58 years (range, 40 to 70 years) were enrolled. All implants survived the observation period. No statistically significant differences were observed in the marginal bone levels of implants with and without fluoride treatment at 6 months and 1, 2, and 3 years (P > .05). No significant relationship was found between marginal bone levels and the recorded resonance frequency analysis values of the implants. CONCLUSIONS: Fluoride treatment of titanium dioxide grit-blasted implants was not effective in preventing marginal bone loss, and primary stability did not affect marginal bone loss around implants placed in anterior mandibles.

Impact of mandibular two-implant retained overdentures on life quality in a group of elderly Turkish edentulous patients.

The aim of the study was to examine the influence of mandibular two-implant retained overdentures on life quality of elderly Turkish patients. The study population comprised 78 edentulous complete denture wearers (aged 65-82) seeking implant-retained mandibular overdentures at Istanbul University, Turkey. Every patient received 2 dental implants in the interforaminal region of the mandible and maxillary conventional dentures and mandibular implant retained overdentures 6 weeks after surgery. Turkish versions of oral health impact profile (OHIP-14) and the United Kingdom oral health-related quality of life (OHQoL-UK) were used for the evaluation of life quality before and after treatment. Compared to pretreatment scores, subjects had statistically significant improvements in life quality after receiving new dentures (p < 0.05). Based on these results, it can be concluded that mandibular two-implant retained overdentures improve the life quality of elderly edentulous Turkish patients.

A quality-of-life comparison between self-aligning and ball attachment systems for 2-implant-retained mandibular overdentures.

The aim of this study was to evaluate the self-aligning overdenture attachment system by comparing its oral health-related quality of life (OHRQL) with a traditionally used ball attachment system. In this randomized, within-subject crossover trial, 25 edentulous subjects each received 2 mandibular implants, and were then assigned to receive either self-aligning or traditional ball attachments. After 3 months, all subjects were switched to the second attachment type. The OHRQL was evaluated for both of the treatments using the short form of the Oral Health Impact Profile (OHIP-14). A subanalysis among subjects with below-average space available for attachment placement was also performed. Wilcoxon signed-rank test was used to compare differences between groups. Scores on the OHIP-14 physical disability domain were significantly better for the self-aligning attachment system (P  =  .049). Among subjects with below-average attachment space, functional limitation, psychological discomfort, physical disability, psychological disability, and total OHIP-14, scores were significantly better for the self-aligning attachment system (P  =  .041, P  =  .047, P  =  .048, P  =  .026, and P  =  .005, respectively). The self-aligning attachment system for 2-implant-retained mandibular overdentures is equal or superior to traditional ball attachments in all domains of the OHIP-14.

A 24-week prospective study comparing the stability of titanium dioxide grit-blasted dental implants with and without fluoride treatment.

PURPOSE: Implant stability has been identified as a factor that may influence the achievement of osseointegration. The aim of this study was to compare the stability of titanium dioxide grit-blasted (TB) dental implants, with fluoride treatment (FTB) and without, over the first 24 weeks following implant placement. MATERIALS AND METHODS: Subjects were edentulous patients visiting a university prosthodontics department over a 6-month period seeking mandibular overdentures retained by two implants. Each patient received two implants in the mandible: one TB and one FTB. All implants were placed by the same surgeon. TB implants were placed in the right canine region and FTB implants were placed in the left canine region. Resonance frequency analysis (RFA) was performed at the time of implant placement and at 1, 2, 3, 4, 5, 6, 12, and 24 weeks postplacement. RESULTS: Twenty-seven patients were enrolled. TB implants showed fluctuations in RFA values during the first 6 weeks, whereas the RFA values of FTB implants remained stable throughout the study period. CONCLUSIONS: FTB implants did not exhibit the early decreases in RFA values seen in TB implants. Larger studies are necessary to confirm this finding and determine whether this will affect clinical loading protocols.

Immediate loading: three cases with up to 38 months of clinical follow-up.

Since the first report describing the placement of dental implants into fresh extraction sockets, there has been an increasing interest in this technique. The advantages of immediate implant placement have been reported to include a reduction in the number of surgical interventions, potentially decreased alveolar bone resorption after tooth loss, and shorter treatment time. Appropriate indications, good surgical technique, and the use of a prosthetic protocol have resulted in success for immediate loading and immediate implantation. Adverse patient-related factors, such as systemic health, a smoking habit, poor oral hygiene, presence of a thin biotype, or an infection in the region of the extraction, are contraindications for this treatment. Patient satisfaction is very high, and some difficulties related to the implantation site in late implantations may be eliminated. This article reports on three cases of immediate loading with up to 30 months of clinical follow-up.

The role of Candida albicans hyphae and Lactobacillus in denture-related stomatitis.

Denture-related stomatitis (DRS) is still a dilemma in removable prosthodontics. The aim of this study was to investigate the relationship of DRS with the presence of Candida albicans hyphae and Lactobacillus. A total of 91 patients wearing maxillary and mandibular complete dentures were included in the present study and tested mycologically as well as bacteriologically. A statistically significant association of DRS was found with denture age (p = 0.003) and continuous denture wearing (p = 0.015). Presence of C. albicans hyphae was shown to be significantly higher in DRS cases (p < 0.01), and there was a statistically significant positive correlation between presence of hyphae and C. albicans (p < 0.01). Another interesting finding was that DRS patients showed higher Lactobacillus counts in their saliva (p = 0.04), as well as in the palate (p = 0.028). C. albicans is an important factor in the development of DRS. Hyphae seem to facilitate the rise of C. albicans counts and be related to the inflammatory response of the tissues. Lactobacillus seems to play an important role in the presence of DRS, as well. In agreement with many other studies, the results of this study confirm the importance of denture age and continuous denture wearing in the development of DRS.

Impression procedures and construction of a sectional denture for a patient with microstomia: a clinical report.

This article describes a modified impression procedure and a method of fabricating a 2-piece collapsible denture for a patient with limited oral opening as a result of the resection of a precancerous lesion on the maxillary lip. Fabricating the denture in 2 pieces (a smaller anterior piece and a larger, hinged, collapsible posterior piece) enabled the patient to place and remove the denture.