Ömer Kutay

Comparison of tensile and peel bond strengths of resilient liners

Previous studies have shown little agreement between the test methods used to assess the bond strength and the mode of failure of resilient liners. This study evaluated the bond strength characteristics of resilient liners by means of 180-degree peeling and butt tensile strength testing. Seventy-two specimens were divided into peel bond and tensile bond specimen groups and were then subdivided into four test groups to evaluate each resilient liner. Tests were conducted with an Instron universal testing machine at a cross-head speed of 2 mm/minute for the tensile specimens and 5 mm/min for the peel specimens. Tensile bond strength and peel bond strength varied significantly among resilient liners except between Novus and Palasiv-62 liners in tensile testing. The mode of failure of Molloplast-B and Novus liners was significantly different between the tensile bond and peel bond test methods. It was concluded that bond strength characteristics can vary according to the test method used.

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.

Influence of surgical technique, implant shape and diameter on the primary stability in cancellous bone

Achievement of primary stability during surgical placement of dental implants is one of the most important factors for successful osseointegration depending on various anatomical, surgical and implant-related factors. Resonance frequency analysis (RFA) has been shown as a non-invasive and objective technique for measuring the stability of implants. The aim of this study was to evaluate the effect of some surgical and implant-related factors in enhancing primary stability and to estimate a correlation between RFA and insertion torque (IT) in proximal regions of cow ribs representing cancellous bone. Fifteen implant beds were prepared in the most proximal region of six fresh cow ribs. Ninety implants with three different shapes and two different diameters were placed with two different surgical techniques, and the primary stability was compared using RFA and IT. Significantly higher RFA and IT values were achieved when under-dimensioned drilling was used as the surgical method (P<0·01); significantly higher IT values were obtained with the use of wider implants (P<0·01) and partially conical Astra Tech implants showed the highest IT values (P<0·01). When all the implants were considered, significant correlations between the IT and RFA values were noted (%40·6, P<0·05). Partially conical implants with a wide diameter to be placed with the modified surgical technique proposed appear to be useful in enhancing the primary stability in cancellous bone.

Influence of platform-switching on marginal bone levels for implants with mandibular overdentures: a retrospective clinical study.

Objective:The aim of this study was to compare bone around platform switched and regular platform implants that support removable prostheses and to report of the clinical outcomes after a loading period of 36 months. Material:Fifty-one patients with a mean age of 59.39 years and 126 implants, appearing in the routine recall sessions consecutively 6, 12, 24, and 36 months after loading with mandibular overdentures, were included in the study group. Bone level measurements were obtained from images of successive radiographs, which were scanned and digitized before, and analyzed at ×20 magnification. Statistical analysis was utilized to assess the mean marginal bone level changes at 6, 12, 24, and 36 months as well as to explore the potential effect of platform switching on bone loss. Results:Although mesial and distal marginal bone loss rates differed in the 6th, 12th, and 24th month recalls between both groups, platform switching caused statistically significant lower bone loss at the 36th month on the mesial as well as distal sides. Conclusion:Platform switching appears to engender lower marginal bone loss around implants supporting removable dentures.

Effect of attachment types and number of implants supporting mandibular overdentures on stress distribution: a computed tomography-based 3D finite element analysis.

The objective of this study was to calculate stresses in bone tissue surrounding uncoupled and splinted implants that are induced by a bite force applied to the mandible and to determine whether the number of mandibular overdenture supporting implants in mandibular bone influence the stress distribution. A human adult edentulous mandible retrieved from a formalin fixed cadaver was used to define the geometry of finite element (FE) model and the FE model was verified with experimental measurements. Following the FE model validation, three different biting situations were simulated for the 2-, 3- and 4-implant retentive anchor as well as bar attachment overdentures under vertical loading of 100 N. As a result of the analyses, it was concluded that an increment in implant number and the splinted attachment type tended to cause lower stresses and the use of two single attachments seems to be a safe and sufficient solution for the treatment of mandibular edentulism with overdentures.

Astra Tech, Brånemark, and ITI implants in the rehabilitation of partial edentulism: two-year results.

Purpose:To explore the soft tissue, marginal bone, and prosthetic complications (if any) of Astra Tech, Brånemark, and ITI implants supporting fixed prostheses during an observation period of 2 years. Materials:The study comprised 26 patients, who received 42 Astra Tech, 36 Brånemark, and 29 ITI implants. After 3 months of healing, abutment connections were performed for Astra Tech and Brånemark implants, and fixed prostheses were delivered to the patients at 4 months. At 6-month, 1-year, and 2-year recall appointments, plaque index, periimplant inflammation index, and bleeding index scores, were recorded. The marginal bone levels were also measured at 2-year recall by means of radiographic evaluation, and prosthetic complications were recorded throughout the study. Results:All implants survived during the 2-year observation period. The plaque index and periimplant inflammation index scores around Brånemark implants were higher than ITI and Astra Tech implants in the first year of function (P > 0.05). Marginal bone loss around ITI and Astra Tech implants was similar at 2 years (P > 0.05). The marginal bone loss around Brånemark implants was higher than Astra Tech implants (P < 0.05) but similar to ITI implants at 2-year recall appointment (P > 0.05). Fixed prostheses supported by ITI and Astra Tech implants did not experience prosthetic complications, and only 1 patient of the Brånemark group had porcelain veneer fracture. Conclusions:Astra Tech, Brånemark, and ITI implants supporting fixed prostheses had same survival rates (100%) in this study. ITI and Astra Tech implants had similar changes in marginal bone levels, whereas Brånemark implants had higher marginal bone loss, particularly in the first year of function.

Mechanical resistance of screwless morse taper and screw-retained implant-abutment connections

OBJECTIVE The screwless morse taper (SMT) implant-abutment connection is an alternative to conventional external or internal screw-retained (ISR) connections. The aim of this in vitro study was to evaluate mechanical resistance of the SMT connection and to compare it with three different ISR connections. MATERIALS AND METHODS Four implant systems were tested in this study: SMT system; Tasarimmed Octo (Istanbul, Turkey), ISR systems; Straumann Bone Level (Basel, Switzerland), Biohorizons Internal (Birmingham, AL, USA), and Dentsply Friadent Xive (Mannheim, Germany). Overall, 64 specimens with stylized single crowns were prepared: 32 for dynamic loading (DL) and 32 for static loading (SL). DL was carried out using a chewing simulator with 120 N at 1.75 Hz for 1.2 × 10(6) cycles, and SL was performed with a universal testing machine at a crosshead speed of 2 mm/min with an angulation of 30°. Cycles until failure from DL and fracture/bending loads at SL were recorded. Statistical analyses were made with Dunns multiple comparison. RESULTS Median cycles until failure in DL were as follows: Octo 86,354 (24,810-153,875), Straumann 1,200,000 (1,156,618-1,200,000), Biohorizons 539,719 (437,224-858,732), Xive 139,411 (139,411-139,411). Median fracture/bending loads in Newton at SL were as follows: Octo 429.6 (404.5-482.7), Straumann 574.6 (544.6-629.9), Biohorizons 548.7 (532.9-567.3), Xive 431.5 (412.5-520.5). There were significant differences between the implant systems under both loading conditions (P ≤ 0.05) revealing that the Octo implant systems SMT connection showed significantly lower cycles to failures and lower fracture/bending loads compared with the ISR connections of the Straumann and Biohorizons implant systems. However, there was no significant difference compared with the Xive implant system. CONCLUSION The mechanical resistance of the screwless morse taper implant system is lower than that of the ISR implant systems that might result in more frequent clinical complications.

A silicone rubber spacer used to determine the optimum thickness for hard and resilient materials in complete dentures

When making a denture with a resilient lining, the problem of controlling the thickness of the resilient lining material is eliminated by use of a spacer. However, controlling the thickness of the hard acrylic resin denture base in these dentures remains a problem and may increase the possibility of fracture. When limited denture space is available, the portions of the denture base subject to fracture should have an accurate if not equal share of the resilient lining material and the hard acrylic resin material. This procedure will minimize the fracture problem of dentures made with resilient lining and is an alternative to conventional spacer procedures.

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.

TEK TAM VE ALT ÜST TAM PROTEZLERDE ÇİĞNEME YETENEĞİNİN DEĞERLENDİRİLMESİ-EVALUATION OF CHEWING ABILITY OF SINGLE AND FULL COMPLETE DENTURES

Ozet Dogal dislerin bir bolumunun veya tumunun kaybedilmesiyle stomatognatik sistemin noromuskuler ve noroartikuler uyumu bozulur. Boylece cigneme fonksiyonundaki verim de duser. Bu calismada, tek cenede ve alt, ust heriki cene kavsindeki dogal dislerin kaybinin cigneme performansinda (C.P) meydana getirdigi degisimler incelenmistir. Bu amaca yonelik olarak, klinigimize basvuran dogal disli 10 hasta (kontrol grubu), ust tam dissiz alt dogal disli 10 hasta, alt tam dissiz ust dogal disli 10 hasta, alt-ust tam dissiz 10 hasta (Deney grubu 1,2,3) olmak uzere toplam 40 hastada cigneme performansi testleri uygulanmistir. C.P degerleri, standart eleklerden gecen cignenmis yerfistigi (test yiyecegi) miktarinin toplam test yiyecegi miktarina bolunmesiyle elde edilmistir. C.P degerleri (% olarak X±Sd) dogal disli hastalarda 79.35±2.97, ust tek tam protez kullanan hastalarda 66.83±5.23, alt tek tam protez kullanan hastalarda 58.76±3.96 ve alt-ust tam protez kullanan hastalarda 50.91±2.76 olarak saptanmistir. Verilerin istatistiksel degerlendirmesi ANOVA ve sonrasinda Tukey HSD testi ile yapilmistir. Deney ve kontrol gruplarindan elde edilen cigneme performansi degerleri arasindaki farklar anlamli bulunmustur (d<0.05). Abstract Neuromuscular and neuroarticular balance of the stomatognatic system would be lost when dental arches become partialy or totaly edentulous. Thus, masticatory function would also be deminished. In this study, the amount of variation in the masticatory performance was investigated for single and full complete denture patients. 40 patients who refered to our clinic were randomly selected and divided in to four groups with 10 patients in each group according to the following criteria. a) all with natural teeth (control) b) with maxillary natural teeth and mandibular edentulous dental arch c) with mandibular natural teeth and maxillary edentulous dental arch and d) completely edentulous. Masticatory performance were measured by dividing the volume of chewed peanuts passing through standard sieves by the volume of the particles poured on each sieve. The masticatory performance data (X±sd as %) for patients with all natural teeth were: 79.35 ± 2.97, for patients having mandibular natural teeth and maxillary edentulous dental arch were: 66.83±5.23, for patients having maxillary natural teeth and mandibular edentulous dental arch were: 58.76±3.96, and for complete edentulous patients were: 50.91 ±2. 76. The statistical analysis of the data were made by using ANOVA and Tukeys HSD test (p<0.05). It was concluded from this study that the means of the all four groups (including control) were found significantly different among each other.