OBJECTIVES: This study aimed to optimize the thread depth and pitch of a recently designed dental implant to provide uniform stress distribution by means of a response surface optimization method available in finite element (FE) software. The sensitivity of simulation to different mechanical parameters was also evaluated. MATERIALS AND METHODS: A three-dimensional model of a tapered dental implant with micro-threads in the upper area and V-shaped threads in the rest of the body was modeled and analyzed using finite element analysis (FEA). An axial load of 100 N was applied to the top of the implants. The model was optimized for thread depth and pitch to determine the optimal stress distribution. In this analysis, micro-threads had 0.25 to 0.3 mm depth and 0.27 to 0.33 mm pitch, and V-shaped threads had 0.405 to 0.495 mm depth and 0.66 to 0.8 mm pitch. RESULTS: The optimized depth and pitch were 0.307 and 0.286 mm for micro-threads and 0.405 and 0.808 mm for V-shaped threads, respectively. In this design, the most effective parameters on stress distribution were the depth and pitch of the micro-threads based on sensitivity analysis results. CONCLUSION: Based on the results of this study, the optimal implant design has micro-threads with 0.307 and 0.286 mm depth and pitch, respectively, in the upper area and V-shaped threads with 0.405 and 0.808 mm depth and pitch in the rest of the body. These results indicate that micro-thread parameters have a greater effect on stress and strain values.
Clothing ; Dental Implants* ; Finite Element Analysis* ; Methods

OBJECTIVES: This study aimed to assess and compare the levels of interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in the crevicular fluid around healthy implants, implants with peri-implantitis, and healthy teeth. MATERIALS AND METHODS: This study evaluated 16 dental implants in 8 patients (4 males and 4 females). These patients had at least one healthy implant and one implant with peri-implantitis next to healthy teeth. The crevicular fluid was collected using absorbent cones and transferred to the laboratory. Specimens were evaluated by ELISA for interleukin levels. Data were analyzed using repeated measures ANOVA and Bonferroni tests (P<0.05). RESULTS: Levels of IL-1beta in the crevicular fluid around implants with peri-implantitis were significantly higher than around healthy implants (P=0.002); the latter was significantly higher than around healthy teeth (P=0.015). A significant difference was found in the level of IL-6 in the crevicular fluid around implants with peri-implantitis and healthy implants (P=0.049) and also between implants with peri-implantitis and healthy teeth (P<0.001). CONCLUSION: Within the limitations of this study, significant differences exist in the levels of IL-1beta and IL-6 in the crevicular fluid of implants with peri-implantitis, healthy implants, and healthy teeth. More studies with larger sample sizes in different populations are necessary.
Cross-Sectional Studies* ; Dental Implants ; Enzyme-Linked Immunosorbent Assay ; Gingival Crevicular Fluid ; Humans ; Interleukin-1beta* ; Interleukin-6* ; Interleukins ; Male ; Peri-Implantitis* ; Sample Size ; Tooth*

PURPOSE: The present study aimed to measure root surface roughness in teeth with periodontitis by a profilometer following root planning with ultrasonic and hand instruments with and without erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation. METHODS: Sixty single-rooted maxillary and mandibular teeth, extracted because of periodontal disease, were collected. The crowns and apices of the roots were cut off using a diamond bur and water coolant. The specimens were mounted in an acrylic resin block such that a plain root surface was accessible. After primary evaluation and setting a baseline, the samples were divided into 4 groups. In group 1, the samples were root planned using a manual curette. The group 2 samples were prepared with an ultrasonic scaler. In group 3, after scaling with hand instrumentation, the roots were treated with a Smart 1240D plus Er:YAG laser and in group 4, the roots were prepared with ultrasonic scaler and subsequently treated with an Er:YAG laser. Root surface roughness was then measured by a profilometer (MahrSurf M300+RD18C system) under controlled laboratory conditions at a temperature of 25degrees C and 41% humidity. The data were analyzed statistically using analysis of variance and a t-test (P<0.05). RESULTS: Significant differences were detected in terms of surface roughness and surface distortion before and after treatment. The average reduction of the surface roughness after treatment in groups 1, 2, 3, and 4 was 1.89, 1.88, 1.40, and 1.52, respectively. These findings revealed no significant differences among the four groups. CONCLUSIONS: An Er:YAG laser as an adjunct to traditional scaling and root planning reduces root surface roughness. However, the surface ultrastructure is more irregular than when using conventional methods.
Crowns ; Dental Instruments ; Humidity ; Laser Therapy ; Periodontal Diseases ; Periodontitis ; Tooth ; Ultrasonics ; Water ; Lasers, Solid-State

PURPOSE: This study aimed to assess the combined effect of dismantling before sterilization and aging on the accuracy (+/-10% of the target torque) of spring-style mechanical torque devices (S-S MTDs). METHODS: Twenty new S-SMTDs from two different manufacturers (Nobel Biocare and Straumann: 10 of each type) were selected and divided into two groups, namely, case (group A) and control (group B). For sterilization, 100 cycles of autoclaving were performed in 100 sequences. In each sequence, 10 repetitions of peak torque values were registered for aging. To measure and assess the output of each device, a Tohnichi torque gauge was used (P<0.05). RESULTS: Before steam sterilization, all of the tested devices stayed within 10% of their target values. After 100 cycles of steam sterilization and aging with or without dismantling of the devices, the Nobel Biocare devices stayed within 10% of their target torque. In the Straumann devices, despite the significant difference between the peak torque and target torque values, the absolute error values stayed within 10% of their target torque. CONCLUSION: Within the limitations of this study, there was no significant difference between the mean and absolute value of error between Nobel Biocare and Straumann S-S MTDs.
Aging* ; Dental Implants ; Steam* ; Sterilization* ; Torque*

OBJECTIVES: The present study was conducted to determine the reproducibility of peri-implant tissue assessment using the new implant success index (ISI) in comparison with the Misch classification. MATERIALS AND METHODS: In this descriptive study, 22 cases of peri-implant soft tissue with different conditions were selected, and color slides were prepared from them. The slides were shown to periodontists, maxillofacial surgeons, prosthodontists and general dentists, and these professionals were asked to score the images according to the Misch classification and ISI. The intra- and inter-observer reproducibility scores of the viewers were assessed and reported using kappa and weighted kappa (WK) tests. RESULTS: Inter-observer reproducibility of the ISI technique between the prosthodontists-periodontists (WK=0.85), prosthodontists-maxillofacial surgeons (WK=0.86) and periodontists-maxillofacial surgeons (WK=0.9) was better than that between general dentists and other specialists. In the two groups of general dentists and maxillofacial surgeons, ISI was more reproducible than the Misch classification system (WK=0.99 versus WK non-calculable, WK=1 and WK=0.86). The intra-observer reproducibility of both methods was equally excellent among periodontists (WK=1). For prosthodontists, the WK was not calculable via any of the methods. CONCLUSION: The intra-observer reproducibility of both the ISI and Misch classification techniques depends on the specialty and expertise of the clinician. Although ISI has more classes, it also has higher reproducibility than simpler classifications due to its ability to provide more detail.
Classification* ; Dentists ; Humans ; Peri-Implantitis* ; Reproducibility of Results* ; Specialization

OBJECTIVES: Dentin is composed of many minerals and growth factors. Based on this composition, we studied its effect as a possible regenerative material for alveolar healing. MATERIALS AND METHODS: This study was conducted using four 2.5-year-old mongrel dogs (male; weight, 25 to 30 kg). The third mandibular premolars were carefully mobilized with a dental elevator and then removed using forceps. The crown portions of the extracted teeth were removed with cutters, and the root portions of the remaining teeth were collectively trimmed as closely as possible to 350 to 500 microm. Dentin and cementum (DC) chips harvested from the extracted teeth were soaked in blood and packed into the fresh sockets (autograft). Biopsies were performed at the ends of day 14 and day 56 following implantation. Data were expressed as mean+/-standard deviation and compared with t-test results. RESULTS: The ratio of SA(bone) to total area of each probe was determined and was 170+/-16 microm2 for the control group and 71+/-14 microm2 for the DC group, a significant difference (P<0.05). CONCLUSION: DC particulate grafts offered no improvement in bone regeneration in alveolar extraction sockets.
Animals ; Bicuspid ; Biopsy ; Bone Regeneration ; Crowns ; Dental Cementum* ; Dentin* ; Dogs* ; Elevators and Escalators ; Intercellular Signaling Peptides and Proteins ; Minerals ; Surgical Instruments ; Tooth ; Tooth Extraction ; Transplants

PURPOSE: The effects of magnetostrictive and piezoelectric devices on tooth surfaces seem to differ with regard to the root surface roughness they produce. This study aimed to compare the results of scaling using magnetostrictive and piezoelectric devices on extracted teeth. METHODS: Forty-four human extracted teeth were assigned to four study groups (n=11). In two groups (C100 and C200), the teeth were scaled using a magnetostrictive device and two different lateral forces: 100 g and 200 g, respectively. In the other two groups (P100 and P200), the teeth were scaled with a piezoelectric device with 100 g and 200 g of lateral force, respectively. he teeth were scaled and the data on the duration of scaling and the amount of surface were collected and analyzed using the t-test. RESULTS: The mean time needed for instrumentation for the piezoelectric and magnetostrictive devices was 50:54 and 41:10, respectively, but their difference was not statistically significant (P=0.171). For root surface roughness, we only found a statistically significantly poorer result for the C200 group in comparison to the P200 group (P=0.033). CONCLUSIONS: This study revealed that applying a piezoelectric scaler with 200 g of lateral force leaves smoother surfaces than a magnetostrictive device with the same lateral force.
Dental Calculus ; Dental Scaling ; Humans ; Tooth ; Tooth Extraction ; Ultrasonics

PURPOSE: Peri-implantitis and periodontitis are inflammatory and infectious diseases of implant and tooth-supporting tissues. Recently, the role of gene polymorphisms of immune response components in the relevant pathogenesis has been investigated. The present study was the first to evaluate the relationship between two known single nucleotide polymorphisms (SNPs) of the receptor activator of nuclear factor kappa-beta (RANK) gene (rs3018362 and rs35211496) in chronic periodontitis and peri-implantitis patients in an Iranian population. METHODS: Eighty-one periodontally healthy patients, 38 patients with peri-implantitis, and 74 patients with chronic periodontitis were enrolled in this study. DNA was extracted from blood arm vein samples by using Miller's salting out technique according to the manufacturer's instructions given in the extraction kit. The concentration of DNA samples was measured using a spectrophotometer. The genetic polymorphisms of the RANK gene were evaluated using a competitive allele specific polymerase chain reaction (KBioscience allele specific PCR) technique. Differences in the frequencies of genotypes and alleles in the diseased and healthy groups were analyzed using chi-squared statistical tests (P<0.05). RESULTS: Analysis of rs35211496 revealed statistically significant differences in the expression of the TT, TC, and CC genotypes among the three groups (P=0.00). No statistically significant difference was detected in this respect between the control group and the chronic periodontitis group. The expression of the GG, GA, and AA genotypes and allele frequencies (rs3018362) showed no statistically significant difference among the three groups (P=0.21). CONCLUSIONS: The results of this study indicate that the CC genotype of the rs35211496 RANK gene polymorphism was significantly associated with peri-implantitis and may be considered a genetic determinant for peri-implantitis, but this needs to be confirmed by further studies in other populations.
Alleles ; Arm ; Chronic Periodontitis ; Communicable Diseases ; DNA ; Gene Frequency ; Genotype ; Humans ; Peri-Implantitis* ; Periodontitis* ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Polymorphism, Single Nucleotide ; Receptor Activator of Nuclear Factor-kappa B ; Veins

PURPOSE: This study aimed to assess the interdental bone level in premolar bitewing radiographs while retracting the cheeks. METHODS: Seventy-two horizontal bone defects were created on dried mandibles and maxillae. The distance from the bone level to the cement-enamel junction of premolars was detected by a modified digital caliper (considered the gold standard). The reliability of all radiographs was assessed by intraclass correlation coefficient (ICC), and the validity was compared to the gold standard using the analysis of variance test. P-values less than 0.05 were considered statistically significant. RESULTS: This study showed that the reliability of radiographs without a cheek simulator and with 0.16 second exposure time was significantly higher than that of the two other groups (ICC=0.96 compared to 0.93 and 0.88, respectively). The results from the radiographs without a cheek simulator and with 0.16 second exposure time were more similar to the gold standard measures than those of the two other groups, although the difference was not statistically significant. CONCLUSIONS: Retracting the buccal soft tissue plays an important role in increasing the accuracy of radiographs in detecting the interdental alveolar bone level and produces more accurate results than increasing the exposure time, although it does not have a significant role in reliability of results.
Alveolar Bone Loss ; Bicuspid* ; Cheek ; Mandible ; Maxilla ; Radiography, Bitewing ; Reproducibility of Results

OBJECTIVES: Chronic periodontitis is a common inflammatory disease of the oral cavity that causes destruction of periodontal tissues and bone around the teeth. Sclerostin is a protein encoded by the SOST gene. In this study, gingival crevicular fluid (GCF) levels of sclerostin in patients with chronic periodontitis were compared with those of healthy subjects. MATERIALS AND METHODS: In this case-control study, a total of 40 subjects were enrolled and divided into the healthy group (n=23) and chronic periodontitis group (n=17). GCF samples were collected, and the concentration of sclerostin was evaluated using enzyme-linked immunosorbent assay. Comparison of significance between groups was assessed using Mann-Whitney U test. RESULTS: Sclerostin concentration was significantly higher in the chronic periodontitis group compared with the healthy group (P < 0.005). CONCLUSION: Despite the limitations of this study, sclerostin can be a possible marker for assessment of periodontal health status.
Case-Control Studies ; Chronic Periodontitis* ; Enzyme-Linked Immunosorbent Assay ; Gingival Crevicular Fluid* ; Healthy Volunteers* ; Humans ; Mouth ; Periodontitis ; Tooth