Effect of material and antagonist type on the wear of occlusal devices with different compositions fabricated by using conventional, additive, and subtractive manufacturing.

STATEMENT OF PROBLEM: Additive (AM) and subtractive (SM) manufacturing have become popular for fabricating occlusal devices with materials of different chemical compositions. However, knowledge on the effect of material and antagonist type on the wear characteristics of occlusal devices fabricated by using different methods is limited. PURPOSE: The purpose of this in vitro study was to evaluate the effect of material and antagonist type on the wear of occlusal devices fabricated by using conventional manufacturing, AM, and SM. MATERIAL AND METHODS: Two-hundred and forty Ø10×2-mm disk-shaped specimens were fabricated by using heat-polymerized polymethylmethacrylate (control, CM), AM clear device resin fabricated in 3 different orientations (horizontal [AMH], diagonal [AMD], and vertical [AMV]), SM polymethylmethacrylate (SMP), and SM ceramic-reinforced polyetheretherketone (SMB) (n=40). Specimens were then divided into 4 groups based on the antagonists: steatite ceramic (SC); multilayered zirconia (ZR); lithium disilicate (EX); and zirconia-reinforced lithium silicate (ZLS) used for thermomechanical aging (n=10). After aging, the volume loss (mm3) and maximum wear depth (µm) were digitally evaluated. Data were analyzed with 2-way analysis of variance and Tukey honestly significant difference tests (α=.05). RESULTS: The interaction between the device material and the antagonist affected volume loss and maximum depth of wear (P<.001). AMH had volume loss and depth of wear that was either similar to or higher than those of other materials (P≤.044). When SC was used, CM had higher volume loss and depth of wear than AMV, and, when EX was used, AMD had higher volume loss and depth of wear than SMP (P≤.013). SC and ZR led to higher volume loss of CM and AMH than EX and led to the highest depth of wear for these materials, while ZR also led to the highest volume loss and depth of wear of AMD and AMV (P≤.019). EX led to the lowest volume loss and depth of wear of AMV and SMP and to the lowest depth of wear of AMH (P≤.021). Regardless of the antagonist, SMB had the lowest volume loss and depth of wear (P≤.005). CONCLUSIONS: AMH mostly had higher volume loss and depth of wear, while SMB had the lowest volume loss, and its depth of wear was not affected by the tested antagonists. ZR mostly led to higher volume loss and maximum depth of wear, while EX mostly led to lower volume loss and maximum depth of wear of the tested occlusal device materials.

Comparative Evaluation of Survival Rates and Marginal Bone Levels of Nonsplinted Immediately Loaded Interforaminal Mandibular Implant-Retained Overdentures: A Randomized Controlled Clinical Trial with 5-Year Results.

PURPOSE: Τo evaluate and compare the marginal bone loss (MBL), survival rates, and periodontal parameters of immediately loaded implants with either Dolder bar or Locator attachments placed in the interforaminal region of edentulous mandibles. MATERIALS AND METHODS: A total of included 19 patients with edentulous mandibles each received two implants in the interforaminal area of the symphysis. Randomly allocated Dolder bar or Locator attachments were then attached immediately, and both clips and a framework were fastened to the denture by the dental laboratory within 24 hours. RESULTS: A total of 28 subjects with 56 implants were treated in accordance with the immediate-loading study protocol. Of these, 9 patients were lost to follow-up; 1 patient reported a serious illness and 8 patients moved and couldn't be reached. The 19 subjects not lost to follow-up (11 women and 8 men; average age: 68 years) were included. Every patient received either two Locator abutments and were assigned to group A (7 patients; 36.8%) or two multiunit abutments and were assigned to group B (12 patients; 63.2%). No implant failure was detected for either group, and therefore the survival rate for both groups was 100% after 5 years. After 5 years without any symptoms, 2 implants from group A and 7 implants from group B showed > 2 mm of MBL, which makes the group A success rate 85.7% and the group B success rate 70.8%. Modified sulcular bleeding index (mSBI) did not differ significantly at any of the measurement intervals. However, the modified plaque index (mPI) of group B was significantly higher than group A at the 60-month follow-up. CONCLUSION: It can be concluded that either splinting or not splinting the immediately loaded interforaminal implants to retain mandibular overdentures (OVDs) does not affect marginal bone levels after 5 years and immediate loading of nonsplinted implants with Locator attachments can be safely preferred to retain mandibular OVDs.

Influence of Multiple Sterilization on Performance of Titanium Pegs When Measuring Implant Stability With Resonance Frequency Analyses.

This in vitro study was conducted to investigate the repeatability of the implant stability quotients (ISQ) measured with multipegs after numerous sterilizations and to detect the exact time when the readings start to deviate. Multipegs were sterilized with 3 different methods (autoclaved, autoclaved + ultrasonic cleaner, chemical disinfection + autoclaved) and grouped according to the method applied. All specimens were put into the autoclave with sealed packages every time they were sterilized. Each specimen was sterilized 50 times according to the technique described in its group after an ISQ measurement was performed. Results of the 2-way analysis of variance showed that neither the sterilization method nor the cycles, nor their interaction, were statistically significant. A multipeg may be reused multiple times after sterilization procedures and may be more cost-effective than a disposable smartpeg for checking implant stability after confirming these results in further investigations.

Reliability and validity of the Turkish version of oral health impact profile for edentulous subjects.

PURPOSE: The validated translations of the OHIP-EDENT exist in different languages; however, there is no reliable and validated Turkish translation. The present study was conducted to evaluate the reliability and to validate the Oral Health Impact Profile in edentulous subjects translated to Turkish (OHIP-EDENT-T). MATERIALS AND METHODS: The study sample included 104 conventional complete denture wearers (58 women and 46 men, mean age: 61.13 ± 9.43 years). The original English version of OHIPEDENT was translated into Turkish using a forward-backward method and applied to the subjects. The reliability of the OHIP-EDENT-T was evaluated using internal consistency and the test-retest method. Validity was determined as construct and convergent validity. The construct validity of OHIP-EDENT-T was assessed using exploratory and confirmatory factor analysis. RESULTS: The Cronbach's alpha value for OHIP-EDENT-T was 0.890. The intraclass correlation coefficient (ICC) was 0.749 for the OHIP-EDENT-T total score, and ICCs for the subscales ranged from 0.630 (95% CI = 0.501-0.823) to 0.859 (95% CI = 0.531-0.897), indicating good to excellent agreement. The Kaiser-Meyer-Olkin value for sampling adequacy was 0.820 and results of Bartlett's sphericity test indicated statistical significance (χ2=1139.767; df=171, p=0.001). This showed that factorial analysis could be applied to the data set. The three-factor structure of the scale explained 81.1% of the observed variance. The agreement of the three-factor solution was further tested with confirmatory factor analysis, and the fit index was found to be acceptable (chi-square fit test=1.449, RMSEA=0.040, GFI=0.94, CFI=0.93). CONCLUSION: Within the limitations of this study, it can be concluded that OHIP-EDENT-T is a valid and reliable instrument for evaluating the quality of life of edentulous patients.

The influence of framework material on stress distribution in maxillary complete-arch fixed prostheses supported by four dental implants: a three-dimensional finite element analysis.

The purpose of the present study was to compare the stress distribution patterns of four materials used for the framework of All-on-4 prostheses. Following framework materials were evaluated: PEKK, PEEK, titanium, and monolithic zirconia. Bilateral 150 N axial and oblique loads were applied in the first molar region and analyzed using FEA. The highest maximum principal stress and minimum principal stress values in cortical bone were found to appear with PEKK and PEEK frameworks around the posterior dental implants upon oblique loading. The fabrication of frameworks from rigid materials in All-on-4 prostheses reduces stress in dental implants and peri-implant bone when the distal implants are tilted 30°.

Technique for Converting A Fractured Implant Locator Abutment to A Custom Implant Cast Post and Core.

This technique article describes an efficient, cost effective and time saving procedure using the fractured abutment as a custom cast post and core when an overdenture abutment is fractured and attempts to retrieve the fractured segment fail.

Reverse Torque Values of Abutment Screws After Dynamic Loading: Effects of Sealant Agents and the Taper of Conical Connections.

The purpose of this in vitro study was to evaluate the influence of taper angle in internal conical connections of implant systems and the application of chlorhexidine gel as an antibacterial agent or polyvinyl siloxane sealant on reverse torque values of abutment screws after dynamic loading. Four implant systems having different taper angles (5.4°, 12°, 45°, 60°) were tested in this study. Test specimens were divided into 3 groups: control (neither chlorhexidine gel filled nor silicone sealed), 2% chlorhexidine gel filled, and silicone sealed. The samples were subjected to a dynamic load of 50 N at 1 Hz for 500 000 cycles before reverse torque measurements. The taper angle of conical connections presented a quantitative positive correlation between the degree of the taper angle and the percentage of tightening torque loss. However, it was significant only between 60° angled connection and others except for the sealant applied groups (P = .013 for control groups and P = .007 for chlorhexidine groups). The percentages of decrease in torque values of silicon sealant-applied specimens were significantly higher than both the control and chlorhexidine groups (P values are .001, .002, .001, and .002, respectively, according to increasing taper angles), but the percentage of decrease in torque values due to chlorhexidine application was not statistically significant when compared with control groups. Gel form chlorhexidine application as an antibacterial agent does not significantly affect the implant-abutment connection stability under dynamic loads. Polyvinyl siloxane sealant may cause screw loosening under functional loads.

Comparison of four-implant-retained overdentures and implant-supported fixed prostheses using the All-on-4 concept in the maxilla in terms of patient satisfaction, quality of life, and marginal bone loss: a 2-year retrospective study.

OBJECTIVE: The purpose of the present study was to compare and assess maxillary edentulous patients treated with four-implant-retained overdentures and with implant-supported fixed prostheses using the All-on-4 concept in terms of patient satisfaction, oral health-related quality of life, and marginal bone loss. METHOD AND MATERIALS: Thirty-three patients treated with either maxillary four-implant-retained overdentures (n = 15) or with maxillary implant-supported fixed prosthesis using the All-on-4 concept (n = 18) were compared in terms of patient satisfaction, quality of life, and marginal bone loss. Independent sample t test was used to compare the two groups in terms of satisfaction, OHIP-14 scores, and marginal bone loss. The paired sample t test was used to compare bone loss at different time intervals. The comparison of marginal bone loss with regard to implant location was accomplished with the one-way ANOVA test. P values of < .05 were considered as statistically significant. RESULTS: No statistically significant differences were found between the two groups' OHIP-14 scores (P > .05). When patient satisfaction scores were evaluated, hygiene maintenance (P = .001) and pain scores (P = .001) were significantly higher in the implant-retained overdenture group than in the implant-supported fixed prosthesis group (P < .05). No statistically significant difference was observed between axial and tilted implants at both the 12-month (P = .59) and 24-month (P = .77) follow-up periods in the implant-supported fixed prosthesis group. CONCLUSION: Four-implant-supported fixed prostheses with the All-on-4 concept and four-implant-retained overdentures present similar marginal bone loss and quality of life scores after 2 years of function. However, patients found overdentures easier to clean but more painful in comparison with the fixed prosthesis.

Custom and prefabricated PolyEtherKetoneKetone (PEKK) post-core systems bond strength: Scanning electron microscopy evaluation.

The present study evaluated the bond strengths of prefabricated PolyEtherKetoneKetone (PEKK) posts, PEKK posts custom-configured according to root-canal size, and conventional fiber posts. A total of 30 maxillary incisors were randomly divided into three groups, as follows: Group 1: fiber posts; Group 2: prefabricated PEKK posts; Group 3; custom-made PEKK posts. Following endodontic treatment, post spaces were prepared, and posts were cemented with resin cement. Push-out bond strength testing was performed using a universal testing machine, and fractures modes were examined under a scanning electron microscope. Data were analyzed using One-way ANOVA and Tukey's HSD tests, with the level of significance set at .05. The highest bond-strength values in the cervical section were observed with the custom-made PEKK post (17.3470 MPa), whereas the highest bond-strength values in the middle and apical sections were observed with the conventional fiber posts (11.5375 MPa and 6.8625 MPa, respectively). Bond-strength values for all posts systems decreased in a cervical to apical direction. PEKK posts are a suitable alternative to fiber posts. Although custom-made PEKK posts demonstrated better bond strength than prefabricated PEKK posts, further studies are needed to evaluate their clinical performance.

Effects of implant-related variables on the marginal bone loss around dental implants.

OBJECTIVE: Marginal bone loss (MBL), a prognostic parameter for implant success, is associated with implant- and patient-related variables. The purpose of this study was to analyze the effects of the crown-to-implant ratio and independent factors of implant diameter, implant length, implant type, location, and platform switching on distal and mesial MBLs at the 6-, 12-, 24-, and 36-month recall sessions of single crown implant-supported restorations. METHOD AND MATERIALS: Radiographic and clinical data of patients treated with single crown implants were collected. MBL was measured at the baseline and recall sessions on panoramic radiographs. The crown-to-implant ratio was calculated by dividing the length of the crown by that of the dental implant. RESULTS: The crown-to-implant ratio had a moderately positive correlation with distal MBL at the 6-month recall session (P < .05, r = 0.469) and a weakly positive correlation at the 12- (P < .05, r = 0.220), 24- (P < .05, r = 0.214), and 36- (P < .05, r = 0.250) month recall sessions. Distal and mesial MBL did not significantly differ among the four implant types at any recall session (P > .05). The crown-to-implant ratio had no significant correlation with mesial MBL at the 12-, 24-, or 36-month recall session (P > .05), and a moderately positive correlation at the 6-month recall session (P < .001, r = 0.434). CONCLUSIONS: MBL was similar among different implant types in the short and medium terms. There was a positive correlation between distal MBL and the crown-to-implant ratio.

Effect of Smoking and Locations of Dental Implants on Peri-Implant Parameters: 3-Year Follow-Up.

BACKGROUND Smoking may be a risk factor for marginal bone loss (MBL) and oral mucosal inflammation surrounding dental implants. This retrospective study evaluated the effects of smoking on dental implants in patients with fixed implant-supported prostheses over a period of 36 months following loading. MATERIAL AND METHODS We assessed 120 patients (68 women, 52 men, ages 19-74 years (mean age: 55.10 years) with 315 implants. Implants were classified according to location in the upper and lower jaws and anterior (placed between canines) or posterior (placed between pre-molars and molars) as follows: 1=maxilla anterior, 2=maxilla posterior, 3=mandible anterior, 4=mandible posterior. We also measured MBL, plaque index (PI), sulcus bleeding index (SBI), and probing depth (PD). P-values less than 0.05 were considered statistically significant. RESULTS MBL was statistically greater in smokers (P<0.001) as compared to non-smokers in both jaws. MBL did not vary significantly by location in either group (smokers: p=0.415; non-smokers: p=0.175). Mean PI and PD scores were significantly higher in smokers as compared to non-smokers (P<0.001). A positive correlation was found between PI and PD scores in both groups. No statistically significant difference in SBI was observed between the 2 groups (P>0.05). CONCLUSIONS Smoking was associated with increases in marginal bone loss around implants, independent of their location in the jaws. Also, both plaque indices and probing depths were greater in smokers than in non-smokers.

The correlation between direction and amount of retrusive movement and condyle position and joint space.

OBJECTIVE: The direction and amount of retrusive movement may be correlated with the amount of joint space and the maximum intercuspal position of the condyle. The aim of this study was to identify any such correlation using an ultrasonic jaw motion analyzer and digital volumetric tomographic (DVT) scans. METHODS: Thirty-five dental students were selected as subjects. DVT scans were obtained using a next-generation i-CAT CBCT unit, and the direction and amount of retrusive movement were measured with a 3-D analyzer. RESULTS: Spearman Rho correlation tests showed no correlation between the amount of retrusive movement and the condyle position and joint space on either the right or left side. DISCUSSION: There is sufficient reason to suggest that retrusive movement of the condyle does not occur in isolation but is influenced by glenoid fossa bone morphology.