Is clinical experience important for obtaining the primary stability of dental implants with aggressive threads? An ex vivo study.

BACKGROUND: The aim of this study was to investigate the clinicians' experience on maintaining the primary stability of implants with aggressive threads belonging to a novel dental implant system. MATERIAL AND METHODS: Three hundred implants with aggressive threads were inserted in fresh bovine ribs mimicking Type IV bone by five clinicians which were classified according to their previous experience of total number of implant insertion. An independent examiner measured the primary stability of all implants after insertion by using resonance frequency analysis (RFA), electronic percussive testing (EPT) and removal torque methods. RESULTS: No significant differences were detected between the stability values measured by the clinicians (p> 0.05) except the Periotest values (PTVs) of the non-experienced clinician. PTVs of the non-experienced clinician were significantly higher than the PTVs of the expert and good clinicians (p<0.05). Significantly higher stability values were detected in the secondary insertion of the non-experienced clinician as compared to her initial insertion values (p<0.05). No significant differences were detected between the first and second measurements of the other clinicians (p> 0.05). CONCLUSIONS: Within the limitations of this ex-vivo study, it may be concluded that experience does not play an important role in maintaining the stability of implants with aggressive threads.

Cytokine gene polymorphism in denture stomatitis patients: A clinical study.

OBJECTIVE: This clinical study investigated the association between cytokine gene polymorphism and Candida growth in denture stomatitis (DS) patients. SUBJECTS AND METHODS: Saliva and blood samples of 160 complete denture wearers (80 healthy controls and 80 with DS) were collected for mycological and gene polymorphism testing, respectively. Salivary Candida growth and TNF-α, TGF-ß, IL-6, and IL-10 genotypes were investigated. Data were analyzed using Student's t test, Mann-Whitney U test, chi-square analysis, and continuity (yates) correction tests (p < .05). RESULTS: Candida albicans colony counts in saliva were significantly higher in the DS group and in the TNF-α GG genotype (p < .05). TGF-ß TC GG and TGF-ß CC GG haplotypes were significantly higher in DS and control groups, respectively (p < .05). C. albicans colony counts were significantly higher in control group in the TGF-ß TC GG haplotype (p < .05). Candida glabrata colony counts were significantly higher in the DS group than the control group in IL-6 GG genotype (p < .05). The difference between DS types in IL-6 genotypes was significant with lower expression level in DS type 3 than DS type 1 and also type 2 (p ≤ .01). CONCLUSION: The significant differences in some genotypes of the TNF-α, TGF-ß, and IL-6 in DS patients are promising in understanding the host defense in DS.

The influence of healing type on marginal bone levels of implants supporting mandibular overdentures: a randomized clinical study.

AIM: The aim of this study was to document the influence of healing type on the marginal bone loss around dental implants placed in the anterior mandible. MATERIALS AND METHODS: A total of 48 edentulous patients rehabilitated with 96 Astra Tech dental implants left to either submerged or nonsubmerged healing were included in the study group. The patients were examined in consecutive routine recall sessions six, 12, and 24 months after loading. The actual bone level measurements were performed by two independent examiners on panoramic X-rays, and the average of both examiners' calculations was used as the marginal bone level value. RESULTS: The marginal bone loss (MBL) of the implants at 6 months was found to be significantly higher in the submerged healing group (P< 0.05). No statistically significant relation was found between the MBL of implants left to submerged healing and that of implants left to non-submerged healing in the other follow-up periods. CONCLUSION: In situations where the dental implant has good primary stability, non-submerged healing can be recommended to avoid a second surgery for healing abutment connection.

A comparative in vitro evaluation of two different magnetic devices detecting the stability of osseo-integrated implants.

BACKGROUND AND OBJECTIVE: It is unknown whether the resonance frequency analysis (RFA) measurements made by two different magnetic resonance frequency analysers are comparable. This in vitro study was designed to compare the RFA measurements made by the two magnetic resonance frequency analysers and to evaluate the intra- and interobserver reliability of the magnetic devices. MATERIAL AND METHODS: Thirty-two implants were placed in four cow ribs. The RFA value of each implant was measured by five different examiners. The measurements were repeated five times, in both the buccal and mesial directions, for each implant at 2 h intervals, and the averages of registered implant stability quotient (ISQ) units were recorded as the buccal ISQ value and the mesial ISQ value for every implant. RESULTS: No statistically significant differences (p>0.05) were observed between the RFA measurements made by the two magnetic devices. The intra-observer reliability of both devices was excellent, whereas the interobserver reliability of the devices was poor. CONCLUSION: The results of the RFA measurements of both tested devices overlap. Although both devices show excellent intra-observer reliability, there are variations between the measurements of different examiners.

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.

The effect of mucine, IgA, urea, and lysozyme on the corrosion behavior of various non-precious dental alloys and pure titanium in artificial saliva.

The corrosion of dental alloys has biological, functional, and aesthetic consequences. Various studies have shown that protein solutions can inhibit the corrosion of alloys. This study is planned to determine the relationship of organic constituents of saliva and the corrosion of dental alloys. The organic constituents are IgA, mucine, urea, and lysozyme which are encountered in the highest amounts in saliva and the dental materials are titanium (Ti), Co-Cr-Mo and Ni-Cr-Mo alloys, and dental amalgam, the most often used metallic components in dentistry. In particular, the interactions between the commonest salivary proteins, IgA, mucine, urea and lysozyme, and Ti, Co-Cr-Mo, Ni-Cr-Mo and dental amalgam were investigated. Each alloy was evaluated by cyclic polarization in each medium. The general anodic and cathodic behavior during forward and reverse cycles, the corrosion and passivation current densities (muA/cm2 ), and the corrosion and the pitting potentials (mV) were determined. The results have shown that Ni-Cr-Mo and dental amalgam alloys are highly susceptible to corrosion in all the investigated media. The Co-Cr-Mo alloy has shown high passive current densities in the solution of mucine and lysozyme in artificial saliva. Titanium instead, has shown a high resistance to corrosion and a stable passive behavior in all media, especially in a solution of mucine and IgA in synthetic saliva. Mucine and IgA, as well as urea and lysozyme, appeared to enhance the formation of a passive film layer on the Ti metal surface, thus inhibiting the corrosion. Based on the study findings, and especially considering the problem of nickel allergy and toxicity of mercury released from dental amalgam, the use of Co-Cr-Mo alloys and Ti to Ni-Cr-Mo alloys is recommended and alternatives to dental amalgam should be sought for patients with impaired salivary flow.