Journal of Dental Medicine

Background and Aims: The exact placement of impression copings in making accurate prosthesis is very important. In some cases, the implants need to be placed deeply subgingival, which could reduce the direct vision and ultimately reduce the precision of impression copings and subsequently, delivered prosthesis. This would be the cause of multiple complications such as delivery of ill-fitting prosthesis. The aim of this study was to evaluate the effect of the dental implant placement depth on the accuracy of impression coping connection by students.

Materials and Methods: This in-vitro and experimental study was conducted by 50 senior dental students. Four implants at different depths (0, 2, 4 and 6 mm) were placed in a model. After learning how to mount impression coping on implants, the students were asked to mount impression copings on all four implants. The samples were examined by an experienced prosthodontist using a magnifier with 4x magnification. Data were analyzed by statistical Cochran test (P<0.05(.

Results: The proper adapting rate of transfer copings, in subgingival implants with the depth of 0, 2, 4 and 6 mm were 100%, 62%, 58% and 20%, respectively. Statistically significant differences were observed between all groups (P<0.001).

Conclusion: The results showed that there was an inverse relationship between the increasing depth of the implants in the gingiva and the dentist’s ability to connect the impression copings properly.

Background and Aims: In recent years, dental implants have received special attention in dentistry. Due to the remarkable success of predictable dental implants, there is growing interests in the scientific community from descriptions of implant success toward identify factors associated with implant failure. The purpose of this study was to identify the risk factors associated with implant failure in an objective and statistically valid manner.
Materials and Methods: To address the research purposes, we used a cohort study in which a total of 2368 implants were placed on 1011 patient in the Clinic of Tehran University of Medical Sciences. The predictor variables included demographic variables, the health status and variables are related to implants. The outcome variable of interest was implant failure. The overall implant survival was estimated using the Kaplan-Meier analysis. First, risk factors were identified using Chi-square test and Fisher's exact test and then the Cox proportional hazard regression models were used for more analysis.
Results: The overall 39 month implant survival using the Kaplan-Meier function was 0.99±0.002. The implant location (jaws) (P=0.049) and type of teeth (P=0.011) were found to have significant relation with failure times in Cox proportional hazard model.
Conclusion: According to result of this study, both implant location and type of teeth had effection the failure times so that, the survival in mandible was higher than maxilla. The failure rate was higher in anterior teeth than that of others (molar, premolar, canine and primary).
 

Background and Aims: For the clinical success of implant-retained prostheses, fitness of matching components and stability of the applied torque to the implant-abutment assembly under dynamic occlusal loading is essential. The aim of this study was to evaluate the torque loss in Co-Cr castable abutments after cyclic loading.
Materials and Methods: 10 castable abutments were cast in Co-Cr alloy with similar size and height. Each specimen was mounted vertically on a separated implant using a 30 Ncm tightening torque. The detorque values of the abutments were evaluated after 10 min. The same tightening torque was applied to the abutments on their corresponding implants and cyclic loading was applied for 500,000 cycles to the implant-abutment assembly. The torque values after cyclic loading were recorded for each specimen. T-test analysis was conducted on scores from the groups.
Resultes: The results of this study showed that the percentage of torque loss in castable abutments was significantly increased after cyclic loading (P<0.001).
Conclusion: Misfit between the castable implant components can cause torque loss before and after cyclic loading. However, it is more appropriate to relate the results of this study to the screw loosening of the above mentioned abutments than judging their clinical performance.

Background and Aims: The aim of this study was to assess the outcome of short implants (<8 mm length) as an alternative to sinus lift surgery and placement of standard-length implants (10-12 mm length) for rehabilitation of atrophic posterior maxilla.
Materials and Methods: In this prospective clinical trial, 26 patients with 6-7 mm of residual alveolar bone height in their atrophic posterior maxilla were randomly divided into two groups (n=13). The test group received short implants without sinus lift surgery while the control group received standard-length implants after maxillary sinus floor augmentation. The bone loss was evaluated at 1 to 2 years after loading of implants on radiographies and the comparison between the two groups was done using chi-square test.
Results: At 1 year, two patients (15.4%) in the short implant and one patient (7.7%) in the standard implant group experienced bone loss (P=0.5). At 2 years, four patients (30.8%) in the short implant and two patients (15.4%) in the standard implant group showed bone loss (P=0.4).
Conclusion: At 2 years after loading, the bone loss was not significantly different around short and standard-length implants. Short implants appeared to be a suitable alternative to sinus lift surgery and placement of standard-length implants for rehabilitation of atrophic posterior maxilla. However, further studies with longer follow ups are still required to cast a final judgment in this respect.

Background and Aims: Diferences whithin shape and size of hand wrenches in diferent systems could affect the torque applied. Therefore, evaluation of wrenches has been emphasized. The aim of the present study was to compare the torque values of the long and short torque wrenches in different implant systems including ITI, Implantium and Nobel Biocare.
Materials and Methods: In this experimental trial, 5 dentists with at least 5 years of professional experience closed the abutment screw in different implants systems using the long and short manual wrenches while the wrench-induced torque values were calculated by digital torque-meter. Torque application was done for 3 times with 10-minutes resting time between each wrench uses in the habitual closing torque manner. Data were analyzed using two-way analysis of variance test in different implant systems, while the paired comparisons were done using Tukey post hoc test.
Results: The maximum torque values of the long manual wrenches were 27.73±4.57 Ncm, 34.6±8.09 Ncm and 30.6±6.94 Ncm for the ITI, Implantium, and Nobel Biocare systems, respectively. While the values were reported to be 26.4±5.3 Ncm, 35.27±7.94 Ncm and 30.13±5.26 Ncm in the short manual wrenches for the ITI, Implantium and Nobel Biocare systems, respectively. Significant differences were found between ITI and Implantium (P<0.0001), and between Implantium and Nobel Biocare systems (P<0.021). However, no significant differences were observed between ITI and Nobel Biocare systems regarding wrench-induced torque values (P>0.05).
Conclusion: From the results, the torque values obtained by different long and short manual wrenches were specific to different implant systems. These values were less in ITI and Nobel Biocare systems and higher in implantun than those range provided for the implant systems by the companies.

Background and Aims: With increasing age and inability to maintain good oral hygiene, the chances of tooth loss increase and the need for dental implants will increase in the future. It also increases the risk of developing peripheral implants, especially at older ages in the failure of implant treatments. Recently, the high prevalence of cardiovascular disease and peri-implantitis in the elderly has been reported. The aim of this study was to investigate the effect of cardiovascular disease on the peri-implantitis in people with failed dental implants.
Materials and Methods: In this retrospective study, the files of patients referred to Shahid Montazeri Dental Clinic from 2009 to 2018 whose their failed implants were extracted, were collected. There were a total of 793 people with failed dental implants. The variables of this study were demographic information including age and sex, health status in terms of cardiovascular disease and peri-implantitis, which were identified and then statistically analyzed by examining the files of patients with these two variables. Data were statistically analyzed by SPSS25 statistical software and Chi-square was used to determine the effective variables.
Results: A total of 793 patients had failed dental implants, including 368 women (46.4%) and 425 men (53.6%) with an average age of 50.79 years. 42 patients (5.3%) had heart disease and 44 (5.5%) had peri-implantitis. According to the Chi-squared test, the significance level was less than 0.05 (P=0.011).
Conclusion: The results of this study showed that the cardiovascular disease and peri-implantitis were significantly related.

Background and Aims: Although dental implants have become a successful and predictable ong-term treatment for patients, not all implant treatments are necessarily successful and pre-implant diseases are spreading. The aim of this study was to determine the prevalence of peri-implantitis in patients one year after prosthetic loading in Khorramabad in 2021.
Materials and Methods: In this cross-sectional study, 53 patients who had implants and undergone prosthetic loading for one year were studied. In each of the 53 patients, the probing depth (PD) and bleeding during probing (BOP) around the implant and the characteristics of the surrounding soft tissue, including gingival redness and tissue sensitivity were evaluated and recorded. To assess the bone level or possible bone resorption, a P.A. graph was taken from the patient using a parallel technique. Information such as demographic characteristics and specialized information about the disease were collected through a checklist. Data were collected using SPSS22 software. Frequency tables and chi-square and t-tests were used to analyze the data.
Results: The mean age of patients participating in the present study was 46.5±10.63 years. The number of women was 33 (62.3%). The prevalence of peri-implantitis was 17% at the patient level and 9.3% at the implant unit level. There was a significant relationship between the age (P<0.03) and systemic disease (P<0.03) with the prevalence of peri-implantitis. However, there was no statistically significant relationship between the prevalence of peri-implantitis and other demographic variables (P<0.05).
Conclusion: The results of the present study showed that the prevalence of peri-implantitis was higher in people with a higher mean age. In addition, systemic diseases are a protective factor for peri-implantitis.

Background and Aims: According to the importance of primary stability on dental implant success and osseointegration, we intend to check and compare the stability and crestal bone loss rate between osteotomy technique and conventional implant insertion techniques.
Materials and Methods: In this study, 26 implants in anterior segment of maxilla in 13 patients were evaluated. The implants were TBR system (Toulouse, France) with 3.5 diameter and 10.5-12 mm length. The implant stability level was recorded immediately after surgery and 3 months later with Ostell mentor. The periapical radiography was taken immediately after surgery, 3 and 6 months to assess crestal bone resorption. Paired t-test and Wilcoxon signed Rank test used for data analysis.
Results: There were no statistically differences between the two treatments techniques in terms of stability (P>0.05). The mean crestal resorption was higher for the osteotomy technique 3 months after implant insertion (P<0.001) but there were no significant differences after 6 months (P=0.678).
Conclusion: Within the limitations of the current study, it can be concluded that the osteotomy it can be considered as a treatment technique in insufficient bone width.

Background and Aims: Despite significant advancements in rehabilitation of edentulism with implants, complications such as implant failure before and after prosthetic loading remain concerns. This study aimed to evaluate the frequency of dental implant failure before and after prosthetic loading in some of Yazd dental clinics between 2018 and 2023.
Materials and Methods: In this descriptive cross-sectional study, 1060 patients’ files from three public dental clinics were reviewed. These patients were treated by dental implants between April 2018 and June 2023. The collected data included patients’ age and gender, implant diameter, brand, and placement site, type of prosthesis, and fixture failure after surgical and prosthetic phases. Data were statistically analyzed by independent t-tests and chi-square tests.
Results: The mean age of patients was 55.25 ± 12.37 years and 56.3% were female. The frequency of overall implant failure was 3.4%. The implant failure rate after prosthetic loading was 2.8% in females and 2.3% in males (P=0.47). This rate was 2% and 1.9% for maxillary and mandibular implants, respectively (P=0.5). This amount was 2.4% in molar areas,1.7% and 1.8% in premolar and anterior regions, respectively  (P=0.8). Implant failure rate was 1.3% in overdentures, 5.9% in cement-retained, and 3.2% in screw-retained prosthesis (P<0.001). This amount for implants with a diameter less than 3.75 mm was 2.6% and for those with a diameter more than 4.5 mm was 3.7% (P<0.001). Implants with a diameter less than 3.75 mm had a 2.6% failure rate, whereas those with a diameter greater than 4.5 mm had a 3.7% failure rate (P<0.001). The implants failure rate was 1.6% for Dio brand and 2.5% for Dentis (P=0.5).
Conclusion: The overall implant failure rate in this study was 3.4%, of which 1.5% occurred before and 1.9% occurred after prosthetic loading. The frequency of implant failure after loading was significantly associated with the implant diameter and prosthesis type. This was not related to the patient's gender, implant site, or the implant brand.