共查询到20条相似文献，搜索用时 15 毫秒
1.
Gary Goldstein Mark Andrawis Mijin Choi Jonathan Wiens Malvin N. Janal 《The Journal of prosthetic dentistry》2017,117(3):426-429
Statement of problem
The definition of centric relation (CR) has been both controversial and divisive, with little consensus.Purpose
The purpose of this study was to determine whether agreement can be reached on a definition for CR among the Fellows of the Academy of Prosthodontics, the organization that writes the Glossary of Prosthodontic Terms.Material and methods
A survey of the Fellows of the Academy of Prosthodontics was conducted at the organization’s annual business meeting.Results
Of the 83 eligible Fellows in attendance, 72 responded to the survey, a response rate of 86%. Of those, the 5 responders who did not indicate a preferred definition and the 2 that chose 2 definitions were censored, yielding an analyzable sample of 65 for the definitions. The most common definition received 19 votes, the next 16, and the third 13, with the other 6 definitions receiving from 2 to 5 votes. Some of the variability in definition depended on the era of training.Conclusions
Disagreement and confusion continues regarding the definition of centric relation. Some of this disagreement can be explained by training era. 相似文献2.
Jong-Eun Kim Joo Hyun Kwon Jee-Hwan Kim June-Sung Shim 《The Journal of prosthetic dentistry》2017,117(5):597-600
Various attempts have been made to transfer the transverse hinge axis and mandibular movement pattern to the mechanical articulator and to fabricate dental prostheses with the fewest errors. However, the occlusal adjustment of a dental prosthesis is always necessary to ensure a precise intraoral fit even when the facebow transfer technique is used in the cast mounting procedure. This is because the true hinge axis is not obtained when the facebow is applied to a patient who exhibits a variable mandible movement pattern rather than a single rotational axis. This technique merges facial scanning data and digital data obtained from a diagnostic cast based on measurements of several landmarks of the anterior teeth and makes it possible to design a dental prosthesis while considering the mandibular opening and closing movements of the patient. This technique could be used to design prosthetic restorations, occlusal splints, and intermediate splints for orthognathic surgery and for complete mouth rehabilitation when changes in vertical dimensions are needed. 相似文献
3.
4.
Jong-Eun Kim Ami Amelya Yooseok Shin June-Sung Shim 《The Journal of prosthetic dentistry》2017,117(6):755-761
Statement of problem
Intraoral scanners have been reported to have limited accuracy in edentulous areas. Large amounts of mobile tissue and the lack of obvious anatomic landmarks make it difficult to acquire a precise digital impression of an edentulous area with an intraoral scanner.Purpose
The purpose of this in vitro study was to determine the effect of an artificial landmark on a long edentulous space on the accuracy outcomes of intraoral digital impressions.Material and methods
A mandibular model containing 4 prepared teeth and an edentulous space of 26 mm in length was used. A blue-light light-emitting diode tabletop scanner was used as a control scanner, and 3 intraoral scanners were used as experimental groups. Five scans were made using each intraoral scanner without an artificial landmark, and another 5 scans were performed after application of an artificial landmark (a 4×3 mm alumina material) on the edentulous area. The obtained datasets were used to evaluate trueness and precision.Results
Without an artificial landmark on the edentulous area, the mean trueness for the intraoral scanner ranged from 36.1 to 38.8 μm and the mean precision ranged from 13.0 to 43.6 μm. With an artificial landmark on the edentulous area, accuracy was improved significantly: the mean trueness was 26.7 to 31.8 μm, and the mean precision was 9.2 to 12.4 μm.Conclusions
The use of an alumina artificial landmark in an edentulous space improved the trueness and precision of the intraoral scanners tested. 相似文献5.
Mario F. Romero Courtney S. Babb Christian Brenes Fernando J. Haddock 《The Journal of prosthetic dentistry》2018,119(4):502-505
A maxillary midline diastema (MMD) is a common complaint of dental patients. An MMD can be closed with treatment from different disciplines, including operative dentistry and orthodontics. A comprehensive smile analysis is also a necessity before beginning treatment. This article highlights the closure of a 3-mm MMD by using a combination of orthodontics and direct composite resin restorations. 相似文献
6.
Ankur Dahiya Nadim Z. Baba Mathew T. Kattadiyil Charles J. Goodacre Akshita Mann 《The Journal of prosthetic dentistry》2019,121(3):504-509
Statement of problem
Excess cement around dental implants is a significant cause of peri-implant inflammation. Research has focused on approaches to cement removal, the type of cement used, and the different instruments used for cement removal with titanium abutments. However, data comparing zirconia with titanium abutments are lacking.Purpose
The purpose of this in vitro study was to compare the effectiveness of excess cement removal from zirconia and titanium custom abutments using an explorer and to compare the effects of cement removal on the abutment surfaces.Material and methods
Implant analogs were placed in a cast in the position of the 2 maxillary central incisors. After creating similar emergence profiles for both the implant abutments, 18 zirconia and titanium custom abutments were fabricated with 1-mm subgingival finish lines on the facial and interproximal areas and an equigingival finish line on the palatal side. The crowns were cemented with zinc oxide-eugenol cement, and a steel explorer was used to remove the excess cement. All abutments were analyzed under a scanning electron microscope for cement remnants and scratches.Results
The mean surface area of cement remnants on the zirconia abutments was 778 ±113 μm2, and for titanium abutments, it was 1123 ±252 μm2, which in terms of the mean percentage area was 3.27% of the total surface area of zirconia and 4.71% of titanium abutments. Only a few abutments from each group showed scratches, and no deep scratches or gouges were observed.Conclusions
Zirconia and titanium abutments had statistically similar cement remnants. Scratches were observed on only a few specimens. 相似文献7.
Statement of problem
Different surface finishing procedures can be applied to monolithic restorations. However, information is limited regarding the long-term performance of these procedures.Purpose
The purpose of this in vitro study was to evaluate the effect of aging on the translucency and color stability of monolithic ceramics with different surface finishing procedures.Material and methods
Disk-shaped (14×1.5 mm) specimens of monolithic zirconia (Zirkonzahn Prettau [ZZ]) and lithium disilicate glass-ceramic (IPS e.max Press [IPS]) were fabricated. The specimens were divided into 3 subgroups according to the surface treatments (n=9, G: glazing, R: rubber polishing system, and P: rubber polishing system followed by polishing paste). Color measurements were made by using a spectrophotometer before and after an ultraviolet aging process. L*, a*, and b* parameters were recorded. ΔE and translucency parameter (TP) values were calculated. One specimen from each subgroup was examined by scanning electron microscopy (×30?000). The data were statistically analyzed using the Mann-Whitney U, Kruskal-Wallis, and post hoc tests (α=.05).Results
ΔE values of group ZZ (5.03) exceeded the clinically acceptable level (3.5); however, the color change was not clinically perceptible for IPS (0.41). The ΔE value of the subgroup P was found to be higher than that of the others for ZZ (P<.001). The ΔE value was not affected by the surface treatment for IPS. Group IPS showed significantly higher translucency than the ZZ group (P<.001). TP values were not affected by the surface treatment in either material and decreased after aging. However, changes in the TP values were too slight to be clinically perceptible.Conclusions
Lithium disilicate ceramic was found to be more esthetic than monolithic zirconia ceramic in terms of color stability and translucency. 相似文献8.
Burak Yilmaz 《The Journal of prosthetic dentistry》2018,119(5):688-692
Computer-aided design and computer-aided manufacturing (CAD-CAM) complete-arch implant-supported fixed prostheses have become popular in recent years and offer several advantages over traditional fabrication techniques. However, they also present challenges, and careful treatment planning is required, particularly for zirconia implant-supported fixed prostheses layered with feldspathic porcelain. This clinical report describes the use of a CAD-CAM high-density polymer implant-supported diagnostic prosthesis to verify the accuracy of the implant impression and evaluate the maxillomandibular relationship, esthetics, and phonetics of the planned CAD-CAM definitive implant-supported fixed prosthesis before CAM processing. 相似文献
9.
Ryan M. Mizumoto Faris Z. Jamjoom Burak Yilmaz 《The Journal of prosthetic dentistry》2018,119(4):552-559
Statement of problem
In implant dentistry, a variety of techniques are used to manage fractured abutment and prosthetic screws. All of them pose various degrees of difficulty to both the clinician and patient and risk involving damage to the implants and prostheses.Purpose
The purpose of this systematic review was to classify and organize the various reported techniques for managing fractured abutment and or prosthetic screws into a risk-based, decision making tree that could be used to guide the clinician through this difficult and time-consuming clinical procedure.Material and methods
A systematic search of the PubMed/MEDLINE database for articles published before June 2016 was performed by 2 independent reviewers. Studies published in English that described a clinical technique to retrieve or manage a fractured abutment or prosthetic screws were included. Techniques were classified according to risk of irreversible damage to the implant. Low-risk techniques were defined as those involving the use of basic hand instruments and instrument modification; moderate-risk techniques were defined as those involving the use of screw retrieval kits, rotary instruments, and screw modification; and high-risk techniques were defined as those involving modification of the implant. Published techniques were then organized into a decision-making tree.Results
A total of 35 articles were included. The reported techniques ranged from straightforward instrumentation and instrument modification to screw or implant modifications. Seven techniques were considered low risk, 17 moderate risk, and 11 high risk.Conclusions
The proposed risk-based decision tree is a useful tool in helping clinicians choose the most appropriate strategy or sequence of strategies that offers maximum benefit to the patient while minimizing associated risks. 相似文献10.
Statement of problem
The demand for ceramic restorations has increased over the past years, and now various machinable materials can be used for chairside computer-aided design and computer aided manufacturing (CAD-CAM) systems. Limited studies of these new materials make it difficult to evaluate their mechanical performance, advantages, and limitations.Purpose
The purpose of this in vitro study was to investigate the fracture resistance of CAD-CAM monolithic ceramic and veneered zirconia molar crowns after thermomechanical aging.Material and methods
A mandibular first molar tooth was prepared, and 12 different experimental groups were generated (n=10). An aging procedure was performed by subjecting the specimens to 12×105 mechanical cycles and 5000 thermocycles. Survival analysis was performed according to the thermomechanical aging. The fracture resistance (load at fracture) of all specimens was evaluated with 1-way analysis of variance after the means had been compared using the Tukey honest significant difference test and Weibull distributions of the experimental groups (α=.05).Results
According to the results, the differences between the fracture resistance of the groups were found to be significant. Restorations in the dual network ceramic crown group fractured catastrophically during thermomechanical aging. In all groups, the highest value was found for monolithic zirconia, followed by monolithic lithium disilicate crowns (P<.05). Both of the monolithic crowns made of lithium disilicate derivates and zirconia crowns veneered with lithium disilicate ceramic showed no differences from each other (P>.05). The Weibull modulus (m) ranged from 4.22 to 8.58, and conventionally veneered and overpressed zirconia showed the lowest Weibull modulus values among the tested groups, indicating greater variation of the data.Conclusions
The highest fracture resistance was observed for yttria-stabilized zirconia crowns, followed by lithium disilicate derivates. Veneered zirconia restorations generally showed lower resistance than these ceramics. The dual network ceramic crowns fractured during thermomechanical aging. 相似文献11.
12.
Hadi AL-Meraikhi Burak Yilmaz Edwin McGlumphy William A. Brantley William M. Johnston 《The Journal of prosthetic dentistry》2018,119(1):116-123
Statement of problem
Computer-aided design and computer-aided manufacturing (CAD-CAM)-fabricated titanium and zirconia implant-supported fixed dental prostheses have become increasingly popular for restoring patients with complete edentulism. However, the distortion level of these frameworks is not well known.Purpose
The purpose of this in vitro study was to compare the 3-dimensional (3D) distortion of CAD-CAM zirconia and titanium implant-fixed screw-retained complete dental prostheses.Material and methods
A master edentulous model with 4 implants at the positions of the maxillary first molars and canines was used. Multiunit abutments (Nobel Biocare) secured to the model were digitally scanned using scan bodies and a laboratory scanner (S600 ARTI; Zirkonzahn). Titanium (n=5) and zirconia (n=5) frameworks were milled using a CAD-CAM system (Zirkonzahn M1; Zirkonzahn). All frameworks were scanned using an industrial computed tomography (CT) scanner (Nikon/X-Tek XT H 225kV MCT Micro-Focus). The direct CT scans were reconstructed to generate standard tessellation language (STL) files. To calculate the 3D distortion of the frameworks, STL files of the CT scans were aligned to the CAD model using a sum of the least squares best-fit algorithm. Surface comparison points were placed on the CAD model on the midfacial aspect of all teeth. The 3D distortion of each direct scan to the CAD model was calculated. In addition, color maps of the scan-to-CAD comparison were constructed using a ±0.500 mm color scale range.Results
Both materials exhibited distortion; however, no significant difference was found in the amount of distortion from the CAD model between the materials (P=.747). Absolute values of deviations from the CAD model were evident in the x and y plane and less so in the z direction.Conclusions
Zirconia and titanium frameworks showed similar 3D distortion compared with the CAD model for the tested CAD-CAM and implant systems. The distortion was more pronounced in the horizontal and sagittal plane than in the vertical plane. 相似文献13.
Jong-Eun Kim Dong-Ho Kwon Jee-Hwan Kim June-Sung Shim 《The Journal of prosthetic dentistry》2019,121(4):566-570
The technique described allowed an implant custom tray to be fabricated referencing the location of connected impression copings. The technique uses dental computer-aided design (CAD) software and 3D printing technology. The method controls the thickness of the impression material around the impression copings, improving the impression-making process. 相似文献
14.
Statement of problemA nonpassive fit of implant-supported restorations can jeopardize the biological and mechanical success of the treatment. Data regarding the fit of different impression techniques for the all-on-4 protocol are limited.PurposeThe purpose of this in vitro study was to digitally evaluate 4 different impression techniques used with the all-on-4 protocol, with distal multiunit analogs positioned in 4 different angulations.Material and methodsFour maxillary definitive cast models with 4 multiunit analogs (T0 32202; NucleOSS) were fabricated according to the all-on-4 treatment protocol. In the anterior region, the analogs were positioned in a parallel direction, whereas in the posterior region, they were positioned in different angulations (0, 10, 20, and 30 degrees). One hundred and sixty models were obtained by using 4 different impression techniques (closed tray without plastic cap, closed tray with plastic cap, splinted open tray, sectioned resplinted open tray) (n=10) and polyvinyl siloxane impression material. Definitive casts and definitive duplicate casts were scanned using a modified laser scanner (Activity 880; Smart Optics Sensortechnik GmbH), and data were transferred to a software program (VRMesh Studio; Virtual Grid Inc). The definitive casts and definitive duplicate cast scans were digitally aligned. Angular and linear deviations in all axes (x, y, and z) of the analogs between definitive and duplicate casts were calculated and subjected to statistical analyses (α=.05).ResultsMean angular deviations were in the range of 0.03 to 0.16 degrees, and linear deviations were in the range of 0.10 to 0.75 mm. The increased angulation between impression copings caused higher linear and angular deviations when closed-tray impression techniques were used (P<.05).ConclusionsReduced linear and angular displacements were obtained from the open-tray impression techniques compared with the closed-tray impression techniques in the angulated groups. Angular and linear deviations increased with the increase in the angulation of the posterior analog. 相似文献
15.
Fusun Ozer Andrew Naden Volkan Turp Francis Mante Deniz Sen Markus B. Blatz 《The Journal of prosthetic dentistry》2018,119(6):987-993
Statement of problem
A recommended minimum thickness for monolithic zirconia restorations has not been reported. Assessing a proper thickness that has the necessary load-bearing capacity but also conserves dental hard tissues is essential.Purpose
The purpose of this in vitro study was to evaluate the effect of thickness and surface modifications on monolithic zirconia after simulated masticatory stresses.Material and methods
Monolithic zirconia disks (10 mm in diameter) were fabricated with 1.3 mm and 0.8 mm thicknesses. For each thickness, 21 disks were fabricated. The specimens of each group were further divided into 3 subgroups (n=7) according to the surface treatments applied: untreated (control), airborne-particle abrasion with 50-μm Al2O3 particles at a pressure of 400 kPa at 10 mm, and grinding with a diamond rotary instrument followed by polishing. The biaxial flexure strength was determined by using a piston-on-3-balls technique in a universal testing machine. Flexural loading was applied with a 1.4-mm diameter steel cylinder, centered on the disk, at a crosshead speed of 0.5 mm/min until fracture occurred. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed. The data were statistically analyzed with 2-way ANOVA, Tamhane T2, 1-way ANOVA, and Student t tests (α=.05).Results
The 1.3-mm specimens had significantly higher flexural strength than the 0.8-mm specimens (P<.05). Airborne-particle abrasion significantly increased the flexural strength (P<.05). Grinding and polishing did not affect the flexural strength of the specimens (P>.05).Conclusions
The mean flexural strength of 0.8-mm and 1.3-mm thick monolithic zirconia was greater than reported masticatory forces. Airborne-particle abrasion increased the flexural strength of monolithic zirconia. Grinding did not affect flexural strength if subsequently polished. 相似文献16.
Necati Kaleli Duygu Sarac Safak Külünk Özgür Öztürk 《The Journal of prosthetic dentistry》2018,119(3):437-445
Statement of problem
In recent years, the use of resin-matrix ceramics and polyetheretherketone (PEEK) abutments has been suggested to absorb excessive stresses on dental implants. However, only a few studies have evaluated the effect of these materials on stress distribution in implants and peripheral bone structure.Purpose
The purpose of this finite element analysis was to evaluate the biomechanical behaviors of resin-matrix ceramics and PEEK customized abutments in terms of stress distribution in implants and peripheral bone.Material and methods
Three-dimensional (3D) models of a bone-level implant system and a titanium base abutment were created by using the standard tessellation language (STL) data of original implant components. An anatomic customized abutment and a maxillary right second premolar crown were then modeled over the titanium base abutment. A bone block representing the maxillary right premolar area was created, and the implant was placed in the bone block with 100% osseointegration. Six different models were created according to combinations of restoration materials (translucent zirconia [TZI], lithium disilicate glass ceramic [IPS], polymer-infiltrated hybrid ceramic [VTE]), and customized abutment materials (PEEK and zirconia). In each model, the implants were loaded vertically (200 N) and obliquely (100 N). The stress distribution in the crown, implant, and abutments was evaluated through the von Mises stress analysis, and the stress distribution in the peripheral bone was examined through the maximum and minimum principal stress analyses.Results
The oblique load resulted in high stress values in the implant components, restorative crown, and cortical bone. Low stress values were observed in the VTE crowns. Zirconia customized abutments exhibited higher stress values than PEEK customized abutments. The stress distributions in the implant and peripheral bone were similar in all models.Conclusions
Changes in restoration and customized abutment material did not affect stress distribution in the implant and peripheral bone. 相似文献17.
Paul Weigl Georgia Trimpou Jonas Lorenz Georg-Hubertus Nentwig Hans-Christoph Lauer 《The Journal of prosthetic dentistry》2019,121(4):618-622
Statement of problem
Nonrigid retainer systems for removable implant superstructures are associated with negative effects such as rocking and increased load on the denture base. Rigid retainer systems such as telescopic crowns reduce these negative effects, but their fabrication demands highly skilled dental technicians and is therefore expensive. Whether a protocol with prefabricated retainers will reduce production time is unclear.Purpose
The purpose of this prospective clinical trial was to evaluate a prefabricated telescopic retainer and a treatment protocol including the intraoral luting of a framework.Material and methods
A total of 23 participants (15 women and 8 men with a mean age of 61.6 ±2.9 years) were included. After 3 dropouts, 21 removable dentures (9 mandibular and 12 maxillary) retained by 91 delayed loaded Ankylos implants were investigated. All implants were restored with prefabricated conically shaped abutments (SynCone-abutment). The prefabricated corresponding cone matrix was assembled intraorally into a metal frame with autopolymerizing resin. After a loading period of 3 years, a follow-up examination investigated the fit of the framework, the prosthetic aftercare, the technical failures, and the retention force. A questionnaire was used to evaluate participant satisfaction. In addition, laboratory fabrication time and costs were compared with those of individually fabricated restorations.Results
One mandibular implant was lost after 25 months (survival rate, 98.9%). The removable dentures showed no apparent rocking and minimal prosthetic maintenance during the 36-month trial. No dentures required relining. The retention force was scored as good in 17 participants and high (with 6 implants in the maxilla) and low (with 2 implants in the mandible) in 2 participants each. No technical failures occurred. An assessment of laboratory fabrication time and costs revealed reduced time and costs. Patient satisfaction was significantly increased (P<.001) over the entire observation time.Conclusions
The SynCone retainer presented a time- and cost-efficient treatment option with sufficient long-term retention for removable dentures and high patient satisfaction. Mandibular prostheses restored with 2 implants had limited success. 相似文献18.
Priscilla Kia Suan Sia Radi Masri Carl F. Driscoll Elaine Romberg 《The Journal of prosthetic dentistry》2017,117(2):283-288
Statement of problem
Currently, no guidelines exist to help in the selection of Locator abutments for implants at different heights.Purpose
The purpose of this in vitro study was to evaluate the effect of the differential heights of pairs of Locator abutments on the retention of overdentures after 6 months of simulated function.Material and methods
In vitro testing was performed with 4 sets of average-sized edentulous mandible analogs with 2 implants placed in the canine positions. There were 10 specimens in each of the 4 groups, with a total sample size of 40. Four groups of 2 implant-retained overdentures were fabricated, with Locator attachments at different vertical levels with differences of 0, 2, 4, and 6 mm. The overdentures were subjected to simulated function for a period corresponding to 6 months of clinical service and then tested with a universal testing machine for changes in peak load-to-dislodgement. The data were analyzed using 1-way ANOVA followed by the Tukey honest significant differences test (α=.05).Results
Varying the heights of Locator abutments had a statistically significant effect on the retentive values of the pink Locator attachments after 6 months of simulated function (F=7.342, P=.001). The peak load-to-dislodgement ranged from 32.3 N (95% confidence interval [CI]: 26.0 to 38.6) for group 0 mm to 53.6 N (95% CI: 46.3 to 60.8) for group 6 mm. When the difference in Locator abutment heights was 2 and 4 mm, the peak load was 37.1 N (95% CI: 32.3 to 42.0) and 41.9 N (95% CI: 31.2 to 52.7). Statistical analysis revealed that the retention of group 0 mm and group 2 mm was significantly lower than group 6 mm. The retention of group 4 mm was not significantly different from groups 0 mm, 2 mm, or 6 mm.Conclusions
Although significant differences were found among the groups, these differences were small and may not be clinically detectable. 相似文献19.
Paola C. Saponaro Damian J. Lee Edwin A. McGlumphy 《The Journal of prosthetic dentistry》2017,117(5):587-591
This clinical report describes the management of a fractured 1-piece zirconia stock abutment from an implant with an internal connection using a modified plastic periodontal probe. This minimally invasive approach allows for the retrieval of fractured prosthetic components without causing irreversible damage to the implant’s platform or its internal threads and does not require special equipment or costly instruments. 相似文献
20.