Rotational Load Fatigue Performance of an Implant System with an Internal Conical Connection and Microthreads.

PURPOSE: This in vitro study investigated the effect of implant geometry and diameter on the rotational load fatigue performance of an implant system with an internal conical connection with microthreads. MATERIALS AND METHODS: Regular (4.2 mm) and wide-diameter (4.8 mm) Astra Tech EV implants with straight (S) and conical (C) geometries were tested with their corresponding titanium abutments, comprising four test groups: 4.2-mm S (Group 1), 4.2-mm C (Group 2), 4.8-mm S (Group 3), and 4.8-mm C (Group 4). Five samples were included in each group. Customized brass implant holders and abutment holders were machined. A rotational load fatigue machine was used to apply a sinusoidally varying load to the implant-abutment interface at an angle of 45 degrees to produce an effective bending moment of 35 Ncm at a frequency of 14 Hz (air temperature: 20°C). The number of cycles to failure was recorded, with the upper limit set at 5 × 106 cycles. Results were analyzed using ANOVA. Failed samples were examined with a scanning electron microscope to evaluate the mode of failure. RESULTS: Of the 20 total samples, 2 failed, with Groups 1 and 2 each reporting one failure. Abutment and abutment screw fracture were observed in the failed sample in Group 1, while implant and abutment screw fracture occurred in the failed sample in Group 2. All wide-diameter implants ran beyond the cut-off without failure, but abutment screw loosening was noted in one sample in Group 3. No significant difference was found between implant groups of different geometries and diameters. Damage to the abutments and the implant internal surface were noted in all failed samples. CONCLUSIONS: While no significant differences were found between the test groups, failures were observed only in the regular-diameter group. The abutment and abutment screw fractured deep within the implant, and the implant fractured below the simulated bone level. These modes of failure may pose a significant clinical challenge during retrieval of these components.

Comparison of 3D positional accuracy of implant analogs in printed resin models versus conventional stone casts: Effect of implant angulation.

PURPOSE: To study the effect of implant angulation on 3D linear and absolute angular distortions of implant analogs in printed resin models and conventional stone casts. MATERIALS AND METHODS: Three sectional master models with two implants with total inter-implant angulations of 0°, 10°, and 20° were fabricated. For each master model, five conventional stone casts (CS) and printed resin models (PM) were fabricated (n = 5). Test models were made with nonsplinted impression copings and open tray polyether impressions for the CS groups and scan bodies scanned using an intraoral scanner for the PM groups. The physical positions of the implants and implant analogs were measured with a coordinate measuring machine. 3D linear distortion (ΔR) and absolute angular distortion (Absdθ) defined the 3D positional accuracy of the analogs in the test models. Univariate ANOVA was used to analyze data followed by post hoc tests (Tukey HSD, α = 0.05). RESULTS: Mean ΔR was significantly greater for PM10 (73.5 ± 8.9 µm) and PM20 (65.5 ± 33.3 µm) compared to CS0 (16.8 ± 14.1 µm), CS10 (22.2 ± 13.0 µm), CS20 (15.6 ± 19.9 µm), and PM0 (23.9 ± 16.1 µm). For Absdθ, there were no significant differences between test groups. CONCLUSIONS: With conventional stone casts, implant angulation had no significant effect on 3D linear and absolute angular distortions. Amongst printed resin models test groups, angulated implants had significantly greater ΔR. Amongst angulated implants test groups, printed resin models had significantly greater ΔR than conventional stone casts. Compared to the master model, all test groups, regardless of inter-implant angulation, produced greater inter-analog distances.

Three-dimensional analysis of the interchangeability of a semiadjustable articulator system in service over time.

STATEMENT OF PROBLEM: Some contemporary articulator systems claim to be highly precise in their interchangeability, with tolerances below 10 µm in vertical error; however, the claims have not been independently verified. PURPOSE: The purpose of this study was to investigate the interchangeability of calibrated semiadjustable articulators in service over time. MATERIAL AND METHODS: A calibrated mounting articulator served as the master articulator, while the test groups were used articulators with a minimum of 1-year use by predoctoral dental students (n=10); used articulators with a minimum of 1-year use by prosthodontic residents (n=10); and new articulators (n=10). One set of mounted maxillary and mandibular master models was positioned in the master and test articulators. High-precision reference markers on the master models were used to determine interarch 3D distance distortions (dRR, dRC, and dRL), interocclusal 3D distance distortion (dRM), interocclusal 2D distance distortions (dxM, dyM, and dzM), and interocclusal angular distortion (dθM) relative to the master articulator. All measurements were conducted three times using a coordinate measuring machine and then averaged to derive the final data set. RESULTS: For interarch 3D distance distortion, the mean dRR ranged from 4.6 ±21.6 µm for new articulators to 56.3 ±47.6 µm for articulators used by prosthodontic residents; mean dRC ranged from 65 ±48.6 µm for new articulators to 119.0 ±58.8 µm for articulators used by prosthodontic residents; and mean dRL ranged from 12.7 ±39.7 µm for articulators used by prosthodontic residents to 62.8 ±75.2 µm for new articulators. For interocclusal 3D distance distortion, the mean dRM ranged from 21.5 ±49.8 µm for new articulators to 68.6 ±64.9 µm for articulators used by predoctoral dental students. For the 2D distance distortions, the mean dxM ranged from -17.9 ±43.4 µm for articulators used by predoctoral dental students to -61.9 ±48.3 µm for articulators used by prosthodontic residents; mean dyM ranged from 18.1 ±59.4 µm for new articulators to 69.3 ±115.1 µm for articulators used by prosthodontic residents; and mean dzM ranged from 29.5 ±20.2 µm for new articulators to 70.1 ±37.8 µm for articulators used by prosthodontic residents. Mean dθM ranged from -0.018 ±0.289 degree for new articulators to 0.141 ±0.267 degree for articulators used by prosthodontic residents. One-way ANOVA by articulator type revealed statistically significant differences among the test groups for dRR (P=.007) and dzM (P=.011) only, where articulators used by prosthodontic residents fared significantly poorer than the other test groups. CONCLUSIONS: The new and used articulators tested did not fulfill the manufacturer's claim of accuracy of up to 10 µm in the vertical dimension. Up to 1 year of time in service, none of the investigated test groups fulfilled the criterion for articulator interchangeability, even if the more lenient threshold of 166 µm were accepted.

Esthetic Evaluation of Anterior Implant-Supported Single Crowns: A Comparison Between Patients and Dentists.

PURPOSE: To compare the esthetic outcomes of anterior implant-supported single crowns as evaluated by patients and clinicians of different specialties. MATERIALS AND METHODS: A total of 133 patients with 138 implant-supported crowns were recalled from the National Dental Centre Singapore Implant Registry to rate the esthetic outcomes of their restorations using a visual analog scale (VAS) questionnaire. Patients with crowns in the maxillary or mandibular canine-to-canine region with a contralateral natural tooth and minimum time in function of 6 months were recruited. Three clinicians trained in prosthodontics rated each restoration using the modified Pink Esthetic Score/White Esthetic Score (PES/WES) index through photographs and models. Two periodontists, two orthodontists, and two general dentists each rated a randomized sample of 40 crowns using the same index for comparison. Statistical analysis was done using a linear mixed model, analysis of variance, intraclass correlation coefficient, kappa score, Spearman rank correlation, and Mann- Whitney U tests. RESULTS: Mean PES, WES, and PES/WES scores for the 138 implants were 4.7, 5.0, and 9.7, respectively. Based on modified PES/WES criteria, 22 (15.9%) of the 138 implants were deemed clinically acceptable. Mean patient VAS scores ranged from 79.3 to 84.4 out of 100. Prosthodontists had significantly lower mean PES, WES, and PES/WES scores (P < .05) than the other specialties. When orthodontists were excluded, papilla scores had the highest agreement of all the variables. CONCLUSION: Patients were less critical of esthetic outcomes than clinicians. A weak correlation was found between patients' subjective evaluations and the modified PES/WES index as rated by prosthodontists. Prosthodontists were the strictest assessors.

Rotational Load Fatigue Performance of Titanium vs Titanium-Zirconium Implant-Abutment Connections.

PURPOSE: Titanium-zirconium (Ti-Zr) alloy has been developed to strengthen the implant body, but clinically relevant information is still limited. The aim of this in vitro study was to compare the rotational load fatigue performance of implant-abutment connections in narrow-diameter (3.3-mm) and regular-diameter (4.1-mm) implants made with commercially pure grade 4 titanium alloy (CPTi-G4) and Ti-Zr. MATERIALS AND METHODS: Narrow-diameter (N) and regular-diameter (R) implants with CPTi-G4 (Ti) or Ti-Zr (Tz) materials were tested. This resulted in four test groups: NTi, NTz, RTi and RTz. Five specimens were made for each group (n = 5). Abutments used were milled from titanium-aluminum-niobium alloy abutment blanks. A rotational load fatigue machine applied a sinusoidally varying load at an angle of 45 degrees to produce an effective bending moment of 35 Ncm at a frequency of 14 Hz in air at 20°C. The number of cycles to failure was recorded. The upper limit was set as 5 million cycles. Results were evaluated using analysis of variance (ANOVA) and Tukey post hoc tests. Failure locations and patterns were evaluated with scanning electron microscope (SEM). RESULTS: All regular-diameter test groups reached the upper limit of 5 million cycles without failure. All narrow-diameter test groups failed within the range of 402,530 cycles to 3,374,353 cycles. It could be observed that NTz showed a higher mean cycle count as compared to NTi. NTi test group recorded two implants damaged, one implant fracture, five abutment fractures, and four screw fractures. NTz test group showed only abutment fractures at the level of implant platform, with no damage to the implant bodies. Significant difference was found between implants of different diameters. There was no significant difference between implants of different materials. CONCLUSION: Regular-diameter implants performed significantly better than narrow-diameter implants, regardless of material, while no significant difference in cyclic load to failure was found between groups of different alloys. All NTz failures were at the abutment only, without damage to the implant. This failure pattern can potentially be clinically advantageous in terms of retrieval and subsequent replacement of a failed prosthesis.

Prevalence and risk factors of erosive tooth wear among young adults in the Singapore military.

OBJECTIVES: Erosive tooth wear (ETW) is defined as the irreversible chemo-mechanical loss of dental hard tissues without plaque or bacteria and has been a growing phenomenon in the general population worldwide. The aim of this study was to determine the prevalence of ETW and the associated risk factors among young military personnel in Singapore. MATERIALS AND METHODS: This cross-sectional study consisted of a questionnaire and clinical examination of military personnel between 18 and 25 years. The questionnaire collected information on demographics, medical and dental history, lifestyle and dietary habits. Tooth wear was clinically evaluated using the Basic Erosive Wear Examination (BEWE) index. The participants were profiled into four risk categories (none, low, moderate, severe) based on the sum score. Multivariable logistic regression analysis was performed to determine the risk factors associated with the presence of ETW. RESULTS: Out of 1296 participants evaluated, 21.8% of them had ETW. The anterior sextants were more affected by erosion than posterior sextants for both arches. The risk factors significantly associated with ETW were GERD (OR = 2.83, p = 0.041), presence of self-reported TMD symptoms (OR = 2.51, p < 0.001), acidic food (OR = 2.03, p < 0.001) and drinks (OR = 3.07, p < 0.001), high caries risk (OR = 4.59, p < 0.001) and toothbrush stiffness (OR = 4.67, p < 0.001). CONCLUSION: ETW is prevalent among the young military population, with over half of the population at a risk of ETW. Gastric reflux disease, TMD, acidic diet, dental caries susceptibility and the use of stiff toothbrushes were identified as significant risk factors. CLINICAL RELEVANCE: A large proportion of young military personnel exhibited mild to moderate risk of ETW. Dental professionals can identify risk-susceptible individuals at a young age and educated them with preventive measures and dietary interventions to prevent the progression of the condition.

Three-dimensional positional accuracy of intraoral and laboratory implant scan bodies.

STATEMENT OF PROBLEM: In the implant digital workflow, scan bodies provide the 3D position of digital implants in the virtual dental arch. However, limited evidence is available on scan body accuracy, selection, and usage. PURPOSE: The purpose of this in vitro study was to evaluate the 3D positional accuracy of 4 intraoral and 6 laboratory scan body systems to the implants and laboratory replicas of an implant system under various torque magnitudes. MATERIAL AND METHODS: Ten test groups comprising 4 intraoral (I): Medentika L-Series (MS), Straumann CARES Mono (SM), Core 3D (CO), Straumann RC (SS); and 6 laboratory (L): Nobel Procera Pos Locator (NP), Sirona InPost (SR), Amann Girrbach (AG), Straumann CARES Mono (SM), Core 3D (CO), Straumann RC (SS) scan bodies were derived from 7 scan body systems. Of these, 3 systems (SM, CO, SS) are used for both intraoral and laboratory applications. The scan bodies were tested on Straumann Bone Level Regular CrossFit implants or laboratory replicas. Eight test groups allowed for the variation of torque application (5, 10, and 15 Ncm), while 2 test groups (NP, SR) were hand positioned only. Prefabricated metal abutments (ME) for both implants and laboratory replicas served as controls. A coordinate measuring machine measured four 3D positional accuracy variables: vertical linear distortion (dz), 2D tolerance displacement (dr), global linear distortion (dR), and scan body height discrepancy (ΔH) (n=10). The data were analyzed with 2-way analysis of variance tests and post hoc analysis with Tukey tests (α=.05). RESULTS: For both intraoral and laboratory test groups, 2-way ANOVA found that the system had a significant effect on all distortion variables (P<.001), while torque magnitude had a significant effect only on dz and ΔH (P<.001). Overall, mean dz ranged from 5 ±12 µm for L-AG at 15 Ncm to 23 ±14 µm for L-AG at 5 Ncm. Mean dr ranged from 5 ±4 µm for I-SM at 15 Ncm to 73 ±41 µm for L-SS at 10 Ncm, and mean dR ranged from 11 ±6 µm for I-SM at 10 Ncm to 74 ±41 µm for L-SS at 10 Ncm. Mean ΔH ranged from -5 ±10 µm for I-SM at 15 Ncm to 23 ±14 µm for L-AG at 5 Ncm. Among intraoral test groups, for dz and ΔH, all the test groups except for I-SM at 15 Ncm and I-MS at 10 and 15 Ncm were significantly more positive than the control (P<.001). For dr, I-SS at 5, 10, and 15 Ncm was significantly different from the control (P<.001). For dR, only I-SS at 5 Ncm was significantly different from the control (P<.001). Among laboratory test groups, for dz and ΔH, L-AG at 5 Ncm and L-CO at 15 Ncm were significantly more positive than the control (P<.001). For dr, L-SS at 10 and 15 Ncm were significantly different from the control (P<.001). For dR, only L-SS at 10 Ncm was significantly different from the control (P<.001). Intraoral and laboratory systems show comparable 3D positional accuracy. CONCLUSIONS: Overall, I-SS and L-SS were the least accurate. The system tested had a significant effect on 3D positional accuracy, while torque magnitude had no consistent effect across all systems.

Accuracy of Implant Analogs in 3D Printed Resin Models.

PURPOSE: To study the effect of implant analog system, print orientation, and analog holder radial offset on 3D linear and absolute angular distortions of implant analogs in 3D printed resin models. MATERIALS AND METHODS: A sectional master model simulating a 2-implant, 3-unit fixed prosthesis in a partially edentulous jaw was fabricated. Three implant analog systems for 3D printed resin models-Straumann (ST), Core3DCentres (CD) and Medentika (MD)-were tested. The corresponding scan bodies were secured onto the implants and scanned using an intraoral scanner. Models were obtained with a Digital Light Processing printer. Each implant analog system had 2 print orientations (transverse [X] and perpendicular [Y] to the printer door) and 2 analog holder radial offsets (0.04 mm and 0.06 mm), for a total of 60 models. The physical positions of the implants in the master model and the analogs in the printed resin models were directly measured with a Coordinate Measuring Machine (CMM). 3D linear distortion (ΔR) and absolute angular distortion (Absdθ) defined the 3D accuracy of the analogs in the printed models. Univariate ANOVA was used to analyse data followed by post hoc tests (Tukey HSD, α = 0.05). RESULTS: Mean ΔR for ST (-155.7 ± 60.6 µm), CD (124.9 ± 65.0 µm) and MD (-92.9 ± 48.0 µm) were significantly different (p < 0.01). Mean Absdθ was not significantly different between ST (0.57 ± 0.48°) and CD (0.41 ± 0.27°), but both were significantly different from MD (2.11 ± 1.14°) (p < 0.01). Print orientation had a significant effect on ΔR only but no discernible trend could be found. Analog holder radial offset had no significant effect on ΔR and Absdθ. CONCLUSIONS: Implant analog system had a significant effect on ΔR and Absdθ. Compared to the master model, CD produced greater mean interanalog distances, while ST and MD produced smaller mean interanalog distances. MD exhibited the greatest mean angular distortion which was significantly greater than ST and CD.

Spectrophotometric and Visual Evaluation of Maxillary Anterior Implant Crowns and Peri-implant Soft Tissues: A Retrospective Study.

PURPOSE: To visually and spectrophotometrically determine the differences in the shades of maxillary anterior implant crowns and peri-implant soft tissues compared to a natural teeth control group. MATERIALS AND METHODS: A total of 44 patients restored with single implant-supported restorations were assessed after at least 6 months in function. Images of the implant crowns, peri-implant soft tissues, and their controls were captured using a spectrophotometer (SpectroShade Micro, Medical High Technologies). Visual assessment of shade differences between the implant crowns and peri-implant soft tissues and their controls were performed by the patients and four dental professionals using a visual analog scale (VAS). Analysis of variance was applied to detect differences between groups. RESULTS: The mean color differences (ΔE) between the implant crowns and peri-implant soft tissues and their respective controls were 4.8 ± 2.6 and 6.6 ± 2.7, respectively. A significant difference (P = .025) in mean ΔE values was observed only at the cervical third of the implant crowns. The patient group showed the highest mean VAS scores for shade matching of the implant crowns (8.4 ± 1.2) and peri-implant soft tissues (7.8 ± 1.6) with their respective controls. CONCLUSION: Spectrophotometric analysis showed significant shade differences at the cervical third of the implant crowns. The patients were more satisfied with the shade matching of their implant restorations than the dental professionals.

A Retrospective Study on the Success, Survival, and Incidence of Complications of Post-Retained Restorations in Premolars Supporting Fixed Dental Prostheses with a Mean of 7 Years in Function.

PURPOSE: To evaluate the survival and success rates of post-and-core restorations supporting fixed dental prostheses (FDPs) after a mean time in function of 7 years and to assess the incidences of biologic and technical complications. MATERIALS AND METHODS: Patients from the National Dental Center Singapore (NDCS) with endodontically treated premolars restored with post-retained FDPs from 2007 to 2009 were recruited from the Endodontic Registry and evaluated by three clinicians. A total of 265 patients with 329 treated premolars were examined clinically. Digital radiographs were also obtained. Complications were classified as tooth- or prosthesis-related. Failure and complication rates were calculated based on person-time-at-risk. RESULTS: The mean time in function was 7.1 years. A total of 25 teeth in 23 patients were lost, resulting in a 7-year survival rate of 92.7% (95% CI: 89.5%, 95.0%). The corresponding success rate was 75.1% (95% CI: 70.5%, 79.1%). A total of 40 FDPs failed, resulting in a 7-year prosthetic survival rate of 88.6% (95% CI: 84.8%, 91.5%). Common complications observed were recurrent periodontal disease (3.9%), periapical pathology (7.3%), caries (3.9%), porcelain chipping (9.9%), and tooth fractures (5.0%). For the incidence of tooth fracture, a risk analysis yielded significant associations with the number of occluding teeth (odds ratio: 4.2; 95% CI: 1.1, 16.7) and the number of adjacent teeth (odds ratio: 4.0, 95% CI: 1.5, 10.9). CONCLUSION: Restoration of premolar teeth requiring root canal treatment with a post and core and crown is a viable treatment when premolar teeth have adjacent teeth.

Comparison of Three-Dimensional Accuracy of Digital and Conventional Implant Impressions: Effect of Interimplant Distance in an Edentulous Arch.

PURPOSE: This study compared the three-dimensional (3D) accuracy of conventional impressions with digital impression systems (intraoral scanners and dental laboratory scanners) for two different interimplant distances in maxillary edentulous arches. MATERIALS AND METHODS: Six impression systems comprising one conventional impression material(Impregum), two intraoral scanners (TRIOS and True Definition), and three dental laboratory scanners (Ceramill Map400, inEos X5, and D900) were evaluated on two completely edentulous maxillary arch master models (A and B) with six and eight implants, respectively. Centroid positions at the implant platform level were derived using either physical or virtual probe hits with a coordinate measuring machine. Comparison of centroid positions between master and test models (n = 5) defined linear distortions (dx, dy, dz), global linear distortions (dR), and 3D reference distance distortions between implants (ΔR). The two-dimensional (2D) angles between the central axis of each implant to the x- or y-axes were compared to derive absolute angular distortions (Absdθx, Absdθy). RESULTS: Model A mean dR ranged from 8.7 ± 8.3 µm to 731.7 ± 62.3 µm. Model B mean dR ranged from 16.3 ± 9 µm to 620.2 ± 63.2 µm. Model A mean Absdθx ranged from 0.021 ± 0.205 degrees to -2.349 ± 0.166 degrees, and mean Absdθy ranged from -0.002 ± 0.160 degrees to -0.932 ± 0.290 degrees. Model B mean Absdθx ranged from -0.007 ± 0.076 degrees to -0.688 ± 0.574 degrees, and mean Absdθy ranged from -0.018 ± 0.048 degrees to -1.052 ± 0.297 degrees. One-way analysis of variance (ANOVA) by Impression system revealed significant differences among test groups for dR and ΔR in both models, with True Definition exhibiting the poorest accuracy. Independent samples t tests for dR, between homologous implant location pairs in Model A versus B, revealed the presence of two to four significant pairings (out of seven possible) for the intraoral scanner systems, in which instances dR was larger in Model A by 110 to 150 µm. CONCLUSION: Reducing interimplant distance may decrease global linear distortions (dR) for intraoral scanner systems, but had no effect on Impregum and the dental laboratory scanner systems. Impregum consistently exhibited the best or second-best accuracy at all implant locations, while True Definition exhibited the poorest accuracy for all linear distortions in both Models A and B. Impression systems could not be consistently ranked for absolute angular distortions.

Associations between symptoms of temporomandibular disorders, quality of life and psychological states in Asian Military Personnel.

BACKGROUND: Symptoms of Temporomandibular Disorders (TMD) could affect oral health-related quality of life (OHRQoL) and psychological distress. OBJECTIVE: This study aims to determine the prevalence of TMD symptoms, and impact of type and number of TMD symptoms on OHRQoL and psychological states among Asian military personnel. METHOD: The study was conducted across 12 military dental centres using self-administered questionnaire comprising demographical data, DC/TMD symptom questionnaire, OHIP-14 and DASS-21. A total of 3028 personnel, aged between 18-65 years old, were invited to participate with an acceptance rate of 90.5%. Data analysis was done using non-parametric tests, regression analysis and Spearman correlation (P < 0.05). RESULTS: Out of 2043 subjects (1998 males; 45 females, mean age 24.18 ± 7.18 years), 36.32% (n = 742) reported at least one TMD symptom. Significant differences in summary OHIP-14, depression, anxiety and stress scores were observed between subjects with and without TMD symptoms. Significant differences in OHIP-14 and DASS-21 scores were observed between dissimilar type and number of TMD symptoms in the TMD group. Those with headaches and 2-3 symptoms have substantially poorer OHRQoL and greater psychological distress. Associations between number of TMD symptoms, quality of life, depression, anxiety and stress were significant but weak (r = 0.19-0.40). CONCLUSIONS: Symptoms of Temporomandibular Disorders were prevalent among Asian military population. Significant differences in OHRQoL and psychological states were observed between subjects with and without TMD symptoms. Specific type and number of TMD symptoms impacted OHRQoL and psychological states differently. Associations between number of TMD symptoms and quality of life, depression, anxiety and stress were significant but weak.

Prevalence of Sleep Bruxism and Its Association with Obstructive Sleep Apnea in Adult Patients: A Retrospective Polysomnographic Investigation.

AIMS: To determine the prevalence of sleep bruxism (SB) in adult obstructive sleep apnea (OSA) patients, to assess the association between SB and OSA in terms of sleep macrostructure and respiratory parameters, and to determine possible OSA risk factors for SB. METHODS: Type I polysomnographic data of 147 adult OSA patients (mean age 44.6 ± 12.8 years) were evaluated for SB. SB episodes were scored when masseter rhythmic masticatory muscle activity (RMMA) was twice the background electromyography amplitude, and SB was established when patients had more than four SB episodes per hour of sleep. Demographic characteristics, sleep macrostructure, and respiratory parameters, including respiratory-related arousal index (RAI), spontaneous arousal index (SAI), oxygen desaturation index (ODI), and Apnea-Hypopnea Index (AHI), were analyzed for differences between patients with and without SB using independent samples t test and Mann-Whitney U test. Multivariate logistic regression analysis was performed to determine the odds of OSA risk factors for SB. RESULTS: Approximately one-third (33.3%) of the adult OSA patients had concomitant SB. Most of the RMMA observed in OSA-SB patients was phasic in nature. OSA patients with SB demonstrated significantly greater RAI (P = .001) and ODI (P = .005). RAI (odds ratio = 1.05, 95% confidence interval = 1.00 to 1.10) and SAI (odds ratio = 0.89, 95% confidence interval = 0.80 to 0.96) demonstrated marginal effects on the odds of experiencing SB. CONCLUSION: About one-third of adult OSA patients had SB, and these patients demonstrated significantly more respiratory-related arousals and oxygen desaturations. These findings suggest that a phenotypic subtype of OSA patients with predominantly phasic SB exists and allude to a possible protective role of RMMA in respiratory-related arousals.

Three-Dimensional Accuracy of Digital Static Interocclusal Registration by Three Intraoral Scanner Systems.

PURPOSE: Prior studies have defined the accuracy of intraoral scanner (IOS) systems but the accuracy of the digital static interocclusal registration function of these systems has not been reported. This study compared the three-dimensional (3D) accuracy of the digital static interocclusal registration of 3 IOS systems using the buccal bite scan function. MATERIALS AND METHODS: Three IOS systems compared were 3MTM True Definition Scanner (TDS), TRIOS Color (TRC), and CEREC AC with CEREC Omnicam (CER). Using each scanner, 7 scans (n = 7) of the mounted and articulated SLA master models were obtained. The measurement targets (SiN reference spheres and implant abutment analogs) were in the opposing models at the right (R), central (C), and left (L) regions; abutments #26 and #36, respectively. A coordinate measuring machine with metrology software compared the physical and virtual targets to derive the global 3D linear distortion between the centroids of the respective target reference spheres and abutment analogs (dRR , dRC , dRL , and dRM ) and 2D distances between the pierce points of the abutment analogs (dXM , dYM , dZM ), with 3 measurement repetitions for each scan. RESULTS: Mean 3D distortion ranged from -471.9 to 31.7 µm for dRR , -579.0 to -87.0 µm for dRC , -381.5 to 69.4 µm for dRL , and -184.9 to -23.1 µm for dRM . Mean 2D distortion ranged from -225.9 to 0.8 µm for dXM , -130.6 to -126.1 µm for dYM , and -34.3 to 26.3 µm for dZM . Significant differences were found for interarch distortions across the three systems. For dRR and dRL , all three test groups were significantly different, whereas for dRC , the TDS was significantly different from the TRC and CER. For 2D distortion, significant differences were found for dXM only. CONCLUSIONS: Interarch and global interocclusal distortions for the three IOS systems were significantly different. TRC performed overall the best and TDS was the worst. The interarch (dRR , dRC , dRL ) and interocclusal (dXM ) distortions observed will affect the magnitude of occlusal contacts of restorations clinically. The final restoration may be either hyperoccluded or infraoccluded, requiring compensations during the CAD design stage or clinical adjustments at issue.

Three-Dimensional Static Articulation Accuracy of Virtual Models - Part I: System Trueness and Precision.

PURPOSE: To evaluate the 3D static articulation accuracy of 3 model scanner-CAD systems (Ceramill Map400 [AG], inEos X5 [SIR], Scanner S600 Arti [ZKN]) using a coordinate measuring machine (CMM). Trueness and precision for each system will be reported in Part I. MATERIALS AND METHODS: The master model simulated a single crown opposing a 3-unit fixed dental prosthesis. Five mounted stone cast sets were prepared, and one set was randomly selected. Reference values were obtained by measuring interarch and interocclusal reference features with the CMM. The stone cast set was scanned 5 times consecutively and articulated virtually with each system (3 test groups, n = 5). STL files of the virtual models were measured with CMM software. dRR , dRC , and dRL , represented interarch global distortions at right, central, and left sides, respectively, while dRM , dXM , dYM , and dZM represented interocclusal global and linear distortions between preparations. RESULTS: For trueness values, mean interarch global distortions ranged from 13.1 to 40.3 µm for dRR , -199.0 to -48.1 µm for dRC , and -114.1 to -47.7 µm for dRL . Mean percentage error of interarch distortion did not exceed 0.6%. Mean interocclusal distortions ranged from 16.0 to 117.0 µm for dRM , -33.1 to 101.3 µm for dXM , 32.9 to 49.9 µm for dYM and -32.0 to 133.1 µm for dZM. ANOVA of trueness found statistically significant differences for dRC , dRL , dRM , dXM , and dZM . For precision values, absolute mean difference between the 10 superimposition combinations ranged from 25.3 to 91.0 µm for dRR , 21.5 to 85.5 µm for dRC , 24.8 to 70.0 µm for dRL . Absolute mean difference ranged from 49.9 to 66.1 µm for dRM , 20.7 to 92.1 µm for dXM , 86.8 to 96.0 µm for dYM , and 36.5 to 100.0 µm for dZM . ANOVA of precision of all test groups found statistically significant differences for dRR , dRC , dRL , dXM and dZM , and the SIR group was the least precise. CONCLUSION: The overall interarch global distortion of all three model scanner-CAD systems was low and did not exceed 0.6%. Variations in scanner technology, virtual articulation algorithm, and use of physical articulators contributed to the differences in distortion observed among all three groups.

Three-Dimensional Static Articulation Accuracy of Virtual Models-Part II: Effect of Model Scanner-CAD Systems and Articulation Method.

PURPOSE: Accurate maxillomandibular relationship transfer is important for CAD/CAM prostheses. This study compared the 3D-accuracy of virtual model static articulation in three laboratory scanner-CAD systems (Ceramill Map400 [AG], inEos X5 [SIR], Scanner S600 Arti [ZKN]) using two virtual articulation methods: mounted models (MO), interocclusal record (IR). MATERIALS AND METHODS: The master model simulated a single crown opposing a 3-unit fixed partial denture. Reference values were obtained by measuring interarch and interocclusal reference features with a coordinate measuring machine (CMM). MO group stone casts were articulator-mounted with acrylic resin bite registrations while IR group casts were hand-articulated with poly(vinyl siloxane) bite registrations. Five test model sets were scanned and articulated virtually with each system (6 test groups, 15 data sets). STL files of the virtual models were measured with CMM software. dRR , dRC , and dRL , represented interarch global distortions at right, central, and left sides, respectively, while dRM , dXM , dYM , and dZM represented interocclusal global and linear distortions between preparations. RESULTS: Mean interarch 3D distortion ranged from -348.7 to 192.2 µm for dRR , -86.3 to 44.1 µm for dRC , and -168.1 to 4.4 µm for dRL . Mean interocclusal distortion ranged from -257.2 to -85.2 µm for dRM , -285.7 to 183.9 µm for dXM , -100.5 to 114.8 µm for dYM , and -269.1 to -50.6 µm for dZM . ANOVA showed that articulation method had significant effect on dRR and dXM , while system had a significant effect on dRR , dRC , dRL , dRM , and dZM . There were significant differences between 6 test groups for dRR, dRL dXM , and dZM . dRR and dXM were significantly greater in AG-IR, and this was significantly different from SIR-IR, ZKN-IR, and all MO groups. CONCLUSIONS: Interarch and interocclusal distances increased in MO groups, while they decreased in IR groups. AG-IR had the greatest interarch distortion as well as interocclusal superior-inferior distortion. The other groups performed similarly to each other, and the overall interarch distortion did not exceed 0.7%. In these systems and articulation methods, interocclusal distortions may result in hyper- or infra-occluded prostheses.

Fabricating CAD/CAM Implant-Retained Mandibular Bar Overdentures: A Clinical and Technical Overview.

This report describes the clinical and technical aspects in the oral rehabilitation of an edentulous patient with knife-edge ridge at the mandibular anterior edentulous region, using implant-retained overdentures. The application of computer-aided design and computer-aided manufacturing (CAD/CAM) in the fabrication of the overdenture framework simplifies the laboratory process of the implant prostheses. The Nobel Procera CAD/CAM System was utilised to produce a lightweight titanium overdenture bar with locator attachments. It is proposed that the digital workflow of CAD/CAM milled implant overdenture bar allows us to avoid numerous technical steps and possibility of casting errors involved in the conventional casting of such bars.

Reliability, failure probability, and strength of resin-based materials for CAD/CAM restorations.

OBJECTIVE:: This study investigated the Weibull parameters and 5% fracture probability of direct, indirect composites, and CAD/CAM composites. MATERIAL AND METHODS:: Discshaped (12 mm diameter x 1 mm thick) specimens were prepared for a direct composite [Z100 (ZO), 3M-ESPE], an indirect laboratory composite [Ceramage (CM), Shofu], and two CAD/CAM composites [Lava Ultimate (LU), 3M ESPE; Vita Enamic (VE), Vita Zahnfabrik] restorations (n=30 for each group). The specimens were polished, stored in distilled water for 24 hours at 37°C. Weibull parameters (m= modulus of Weibull, σ0= characteristic strength) and flexural strength for 5% fracture probability (σ5%) were determined using a piston-on-three-balls device at 1 MPa/s in distilled water. Statistical analysis for biaxial flexural strength analysis were performed either by both one-way ANOVA and Tukey's post hoc (α=0.05) or by Pearson's correlation test. RESULTS:: Ranking of m was: VE (19.5), LU (14.5), CM (11.7), and ZO (9.6). Ranking of σ0 (MPa) was: LU (218.1), ZO (210.4), CM (209.0), and VE (126.5). σ5% (MPa) was 177.9 for LU, 163.2 for CM, 154.7 for Z0, and 108.7 for VE. There was no significant difference in the m for ZO, CM, and LU. VE presented the highest m value and significantly higher than ZO. For σ0 and σ5%, ZO, CM, and LU were similar but higher than VE. CONCLUSION:: The strength characteristics of CAD/ CAM composites vary according to their composition and microstructure. VE presented the lowest strength and highest Weibull modulus among the materials.

Reliability, failure probability, and strength of resin-based materials for CAD/CAM restorations

ABSTRACT Objective: This study investigated the Weibull parameters and 5% fracture probability of direct, indirect composites, and CAD/CAM composites. Material and Methods: Discshaped (12 mm diameter x 1 mm thick) specimens were prepared for a direct composite [Z100 (ZO), 3M-ESPE], an indirect laboratory composite [Ceramage (CM), Shofu], and two CAD/CAM composites [Lava Ultimate (LU), 3M ESPE; Vita Enamic (VE), Vita Zahnfabrik] restorations (n=30 for each group). The specimens were polished, stored in distilled water for 24 hours at 37°C. Weibull parameters (m= modulus of Weibull, σ0= characteristic strength) and flexural strength for 5% fracture probability (σ5%) were determined using a piston-on-three-balls device at 1 MPa/s in distilled water. Statistical analysis for biaxial flexural strength analysis were performed either by both one-way ANOVA and Tukey's post hoc (α=0.05) or by Pearson's correlation test. Results: Ranking of m was: VE (19.5), LU (14.5), CM (11.7), and ZO (9.6). Ranking of σ0 (MPa) was: LU (218.1), ZO (210.4), CM (209.0), and VE (126.5). σ5% (MPa) was 177.9 for LU, 163.2 for CM, 154.7 for Z0, and 108.7 for VE. There was no significant difference in the m for ZO, CM, and LU. VE presented the highest m value and significantly higher than ZO. For σ0 and σ5%, ZO, CM, and LU were similar but higher than VE. Conclusion: The strength characteristics of CAD/ CAM composites vary according to their composition and microstructure. VE presented the lowest strength and highest Weibull modulus among the materials.

Three-dimensional repositioning accuracy of semiadjustable articulator cast mounting systems.

STATEMENT OF PROBLEM: In spite of its importance in prosthesis precision and quality, the 3-dimensional repositioning accuracy of cast mounting systems has not been reported in detail. PURPOSE: The purpose of this study was to quantify the 3-dimensional repositioning accuracy of 6 selected cast mounting systems. Five magnetic mounting systems were compared with a conventional screw-on system. MATERIAL AND METHODS: Six systems on 3 semiadjustable articulators were evaluated: Denar Mark II with conventional screw-on mounting plates (DENSCR) and magnetic mounting system with converter plates (DENCON); Denar Mark 330 with in-built magnetic mounting system (DENMAG) and disposable mounting plates; and Artex CP with blue (ARTBLU), white (ARTWHI), and black (ARTBLA) magnetic mounting plates. Test casts with 3 high-precision ceramic ball bearings at the mandibular central incisor (Point I) and the right and left second molar (Point R; Point L) positions were mounted on 5 mounting plates (n=5) for all 6 systems. Each cast was repositioned 10 times by 4 operators in random order. Nine linear (Ix, Iy, Iz; Rx, Ry, Rz; Lx, Ly, Lz) and 3 angular (anteroposterior, mediolateral, twisting) displacements were measured with a coordinate measuring machine. The mean standard deviations of the linear and angular displacements defined repositioning accuracy. RESULTS: Anteroposterior linear repositioning accuracy ranged from 23.8 ±3.7 µm (DENCON) to 4.9 ±3.2 µm (DENSCR). Mediolateral linear repositioning accuracy ranged from 46.0 ±8.0 µm (DENCON) to 3.7 ±1.5 µm (ARTBLU), and vertical linear repositioning accuracy ranged from 7.2 ±9.6 µm (DENMAG) to 1.5 ±0.9 µm (ARTBLU). Anteroposterior angular repositioning accuracy ranged from 0.0084 ±0.0080 degrees (DENCON) to 0.0020 ±0.0006 degrees (ARTBLU), and mediolateral angular repositioning accuracy ranged from 0.0120 ±0.0111 degrees (ARTWHI) to 0.0027 ±0.0008 degrees (ARTBLU). Twisting angular repositioning accuracy ranged from 0.0419 ±0.0176 degrees (DENCON) to 0.0042 ±0.0038 degrees (ARTBLA). One-way ANOVA found significant differences (P<.05) among all systems for Iy, Ry, Lx, Ly, and twisting. CONCLUSIONS: Generally, vertical linear displacements were less likely to reach the threshold of clinical detectability compared with anteroposterior or mediolateral linear displacements. The overall repositioning accuracy of DENSCR was comparable with 4 magnetic mounting systems (DENMAG, ARTBLU, ARTWHI, ARTBLA). DENCON exhibited the worst repositioning accuracy for Iy, Ry, Lx, Ly, and twisting.