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1.
Clin Oral Investig ; 2021 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-34622309

RESUMO

OBJECTIVES: To assess alveolar bone changes and treatment modality alterations after ridge preservation on maxillary molar extraction sockets with severe periodontitis, compared to natural healing. MATERIAL AND METHODS: Thirty-six maxillary infected-molar teeth either receiving ridge preservation (RG group) or undergoing natural healing (NT group) were investigated. Cone-beam computed tomography (CBCT) scanning was performed immediately after surgery (the baseline) and repeated 6 months later to measure the linear and volumetric changes of the sockets. RESULTS: Based on radiographic measurements, alveolar bone width decreased by 1.58 ± 4.61 mm in the NT group but increased by 3.74 ± 4.17 mm in the RG group (p < 0.05). Significant increases in ridge height at the center of both the NT (7.54 ± 4.54 mm) and RG (9.20 ± 3.26 mm) groups were observed. Mean sinus pneumatization was 0.19 ± 0.45 mm in the RG group and 0.59 ± 0.63 mm in the NT group (p < 0.05). The relative increase in total ridge volume was 8.0% and 35.5% in the NT and RG group, respectively (p < 0.05). Implant placement with additional sinus augmentation procedure was performed in 16.7% of the RG group cases, whereas 50% in the NT group cases. CONCLUSIONS: Ridge preservation in the maxillary molar extraction sockets with severe periodontitis can improve alveolar ridge dimensions and decrease the necessity of advanced regenerative procedures at implant placement compared to natural healing. CLINICAL RELEVANCE: Ridge preservation on maxillary molar extraction sockets with severe periodontitis maintained the vertical bone height more efficiently and resulted in less need for sinus augmentation procedures at 6 months compared to natural healing.

2.
J Prosthet Dent ; 2021 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34482966

RESUMO

STATEMENT OF PROBLEM: The output torque delivered by a dental implant toggle-style torque wrench is known to be affected by activation rate. The International Organization for Standardization (ISO) established the ISO 6789-1 standard to provide guidance on activation rates relative to desired output torque in the Nm torque range. Whether the ISO 6789-1 standard applies at the relatively lower dental torque ranges is not known, and little information is available on the activation rates that clinicians use and how this may affect output torque. PURPOSE: The purpose of this in vitro study was to determine how output torque values vary with the activation rates used by clinicians at dental implant-relevant target torque values. MATERIAL AND METHODS: To determine clinically relevant activation rates, a new adjustable dental implant toggle-style torque wrench was activated from 0 to 25 Ncm target torque by 5 prosthodontists by using a custom mandibular and maxillary typodont model containing implants and abutments with screws. This provided a baseline of activation rates (mm/sec). Data were transferred to a computerized numerical control model incorporating a variable speed linear motor, which was used to drive a dental implant toggle-style torque wrench attached to an electronic torque measuring device. Constant speed and a regulated dual-speed-assigned 80/20 rate group, where 80% of target torque value was delivered first, then a pause, and the final 20% at different speeds as suggested by the ISO 6789-1 standard, were evaluated. Fast, medium, and slow rates were categorized and applied with target torque values of 10, 25, and 35 Ncm, respectively, for n=12 activations. The output torque values were recorded for both constant and 80/20 groups and compared with the desired target torque values. Data were statistically analyzed with 1-way ANOVA and the Scheffé post hoc paired t test (α=.05). RESULTS: The clinicians' activation rates from 0 to 25 Ncm on the typodont model converted into linear speeds resulted in fast =24.19 mm/sec, medium =14.5 mm/sec, and slow =7.25 mm/sec. When actioned at a constant rate, the mean output torque values were generally in the order of slow > medium > fast in activation rates. Generally, precision output torque decreased as target torque increased, especially when slow and medium rates, either constant or regulated 80/20 were used. All mean output torque for slow, medium, and their 80/20 variants were greater than target torque. Fast and 80/20 fast produced the lowest mean output torque values for all torque settings, and at the 35 Ncm setting, the dental implant toggle-style torque wrench output torque mean values were lower than target torque. Statistically significant differences (P<.05) were found among groups, most notably in the 80/20 dual-speed groups, especially in comparisons with the 80/20 fast rate group. When the target torque value was 10 Ncm with the 80/20 fast rate, the output torque value deviated from the maximum ISO limit by more than 6%. CONCLUSIONS: The rate of actioning a dental implant toggle-style torque wrench influenced the delivered torque value, with fast rate actioning producing lower and less precise output torque values.

3.
Int J Oral Maxillofac Implants ; 36(3): 538-545, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34115069

RESUMO

PURPOSE: The purpose of this study was to survey practicing clinicians and determine if differences existed concerning their use of torque-limiting devices (TLDs) and screw-tightening protocols, comparing this with existing universal industry standards. MATERIALS AND METHODS: A nine-question survey was administered with 428 dentists providing data for three specific areas: (1) demographic information-TLD ownership, device age, frequency of use, and observations of screw loosening; (2) recognition information-calibration, reading measurements of the TLD, and the meaning of preload; (3) usage information-screw-tightening protocols and effect of speed during actioning of the TLD. Data collection was compared with industry standards for use of hand torque tools including ISO-6789 1,2:2017 and related texts pertaining to screw fastener protocols. RESULTS: The beam-type TLD was the most popular; however, 33% surveyed used it incorrectly. Most TLDs being used were older than 1 year, with only 6% calibrated. Forty-eight percent observed screw loosening less than once per year, while 44% reported three or more occurrences per year. A similar number used the TLD for implant placement and abutment screw tightening. Screw-tightening protocols varied. Preload was not understood by the majority of those surveyed. CONCLUSION: Dentistry does not appear to adhere to the protocols and standards recommended by other industries that also rely on screw-fastening mechanisms and TLDs. Further education and training appears to be warranted in this area of implant dentistry to reduce the risks of screw-associated complications.


Assuntos
Dente Suporte , Implantes Dentários , Parafusos Ósseos , Análise do Estresse Dentário , Torque
4.
Artigo em Inglês | MEDLINE | ID: mdl-33819334

RESUMO

The efficacy of the socket preservation procedure using deproteinized bovine bone mineral, bioabsorbable collagen membrane, and collagen sponge on molar extraction sites with severe periodontitis was assessed at 6 postoperative months, before implant placement. Results revealed excellent soft tissue healing without loss of keratinized tissue and no statistically significant differences in socket marginal bone changes in 20 molar extraction sockets. High levels of primary implant stability were recorded. Socket preservation using a minimally invasive surgical technique provides good soft and hard tissue healing as well as anticipated stability of implant placement at sites of extracted molars with severe periodontitis.


Assuntos
Perda do Osso Alveolar , Periodontite , Perda do Osso Alveolar/prevenção & controle , Perda do Osso Alveolar/cirurgia , Animais , Bovinos , Humanos , Dente Molar/cirurgia , Periodontite/cirurgia , Extração Dentária , Alvéolo Dental/cirurgia
5.
BMC Oral Health ; 21(1): 184, 2021 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-33845803

RESUMO

BACKGROUND: Information regarding the reaction of bone augmentation in terms to sinus mucosa thickness of periodontally compromised molar extraction sites is limited. This retrospective study aimed to analyze the effect of ridge preservation procedures following the extraction of molars with severe periodontitis on the healing pattern of adjacent maxillary sinus mucosal membranes. METHODS: Thirty-one periodontally compromised maxillary molar teeth either receiving ridge preservation (test group, n = 20) or undergoing spontaneous healing (control group, n = 11) were investigated. Cone-beam computed tomography (CBCT) scanning was performed before the extraction procedure and repeated 6 months later. The mucosa thickness (MT) of the adjacent periodontally compromised molar tooth was measured from CBCT images before tooth extraction and after 6 months of healing at nine assigned measurement points. The data were analyzed at α = 0.05. RESULTS: The prevalence of pre-extraction maxillary sinus mucosal thickening was 60.0% and 63.6% in the test and control groups, respectively. The average MT of the thickened sinus mucosa before tooth extraction was 3.78 ± 2.36 mm in the test group and 4.63 ± 3.20 mm in the control group (P = 0.063). The mean mucosal thickening reductions in the thickened MT subjects after 6 months of healing were 2.20 ± 2.05 mm (test group) and 2.64 ± 2.70 mm (control group), P = 0.289. The differences of MT between the time prior to extraction and after 6 months of healing were statistically significant within both groups (P < 0.05). CONCLUSIONS: Following extraction of molars with severe periodontitis, a reduction in swelling of the Schneiderian membrane has been observed regardless of the addition of a DBBM socket graft. However, a mucosal thickness > 2 mm was still frequently observed.


Assuntos
Perda do Osso Alveolar , Periodontite , Tomografia Computadorizada de Feixe Cônico , Humanos , Dente Molar/diagnóstico por imagem , Dente Molar/cirurgia , Mucosa Nasal/diagnóstico por imagem , Periodontite/diagnóstico por imagem , Projetos Piloto , Estudos Retrospectivos , Extração Dentária
6.
Clin Oral Implants Res ; 32(7): 799-807, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33755996

RESUMO

OBJECTIVES: To evaluate the dimensional changes of the keratinized tissue width (KTW) in molar regions after augmentation by free gingival grafts (FGG) before implant placement. MATERIAL AND METHODS: In seventeen patients, twenty implant sites in molar regions with KTW ≤3 mm at the buccal aspect received FGG 2 months before implant placement. KTW at the buccal aspect was measured before FGG (T0), immediately before implant placement (T1), at the time of impression taking for final prosthesis fabrication (T2), and at the end of the follow-up period after loading (T3, 12-48 months). Changes in KTW before and after FGG, as well as the alterations during the follow-up period after loading, were analyzed. Shapiro-Wilk test, paired Student's t test, and Wilcoxon signed-rank test were used for the data analysis at α = 0.05. RESULTS: KTW at the buccal aspect of the alveolar ridge was observed with a significant gain of 5.9 ± 1.3 mm at T1 (p < .001). The shrinkage of KTW from T2 to T3 was 8.5%, which was limited but statistically significant (p = .008). KTW at the buccal aspect of implant restorations was 5.0 ± 1.5 mm at T3. CONCLUSIONS: Within the limitations of the present study, our data suggest that using FGG to increase KTW in molar regions before implant placement had a predictable result. The buccal KTW had a limited reduction and was ≥3 mm with more than 12 months of follow-up after loading.


Assuntos
Implantes Dentários , Processo Alveolar , Gengiva , Humanos , Dente Molar/cirurgia , Estudos Retrospectivos , Resultado do Tratamento
7.
Sensors (Basel) ; 21(3)2021 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-33499198

RESUMO

Different techniques have been used to construct provisional crowns to protect prepared teeth. The purpose of this in vitro study was to assess the internal fit and marginal discrepancy of provisional crowns made by different methods. A total of 48 provisional crowns were constructed and divided into three groups (n = 16) according to the fabrication methods: fabricated manually-group MAN; computer-aided design/computer aided manufacturing technology-group CAM; and 3-dimensional (3D)-printed technology-group 3DP. The same standard tessellation language (STL) file was used for both CAD/CAM and 3D-printed group. The silicone-checked method was used to measure the internal gap distance. The marginal discrepancy was measured by using the polyvinyl siloxane (PVS) replica method and swept-source optical coherence tomography (OCT) scanning technique. Data were analyzed with one-way analysis of variance (ANOVA) nonparametric Kruskal-Wallis and Tukey tests at α = 0.05. At the central pit and axial walls, the gap distance mean values of group CAM were higher than those from group MAN and 3DP. The group 3DP was statistically significantly higher in gap distance at the location of occlusion than group MAN and group CAM (p < 0.05). The total gap distances assessed by silicone-checked method revealed there were no statistically significant differences between the tested groups (p > 0.05). The total mean values of absolute and horizontal marginal discrepancy of the group 3DP obtained by using the PVS-replica method and OCT scanning technique were significantly higher than the group MAN and CAM (p < 0.05). Regression correlation results of marginal discrepancy indicated a positive correlation (r = 0.902) between PVS-replica method and OCT scanning technique. The manually fabricated provisional crowns presented better internal fit and a smaller marginal discrepancy. Between different assessment techniques for marginal adaptation, PVS-replica method and OCT scanning technique have a positive correlation.


Assuntos
Desenho Assistido por Computador , Coroas , Humanos
8.
J Prosthet Dent ; 125(3): 407-410, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32418666

RESUMO

The dental torque limiting device is a tool used to deliver a measured torque to implants and to their associated components. The torque delivery must be accurate and precise, especially when considering screw joints. Similar torque wrenches are used in various industries, and recommendations on calibration are provided by the International Organization for Standardization 6789-2:2017. It states that hand torque tools should be calibrated annually or more frequently if subjected to extreme temperature conditions such as steam sterilization. The International Organization for Standardization standard recommends that calibration may be performed by direct comparison of 2 torque devices provided that 1 is known to be within calibration. This technique article describes the procedures for fabricating a tool that couples 2 dental torque limiting devices. It may be used for calibrating and validating both electrical and mechanical torque limiting devices.


Assuntos
Parafusos Ósseos , Implantes Dentários , Dente Suporte , Análise do Estresse Dentário , Vapor , Esterilização , Torque
9.
PeerJ ; 8: e10006, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33024638

RESUMO

Background: The aim of this study was to measure the morphology of interdental papillae (IP) in maxillary anterior teeth using cone-beam computed tomography (CBCT). Methods: Twenty-seven periodontally healthy subjects with 135 IP were evaluated by means of periodontal examination and a CBCT scan with an elastomeric matrix containing radiopaque material in position. According to the status of tooth contact and presence of IP, subjects were categorized into three groups: open contact point, complete papillae, and deficient papillae group. The papillae height (PH), facial-lingual thickness (FLT), and interdental distance (IDD) were measured. Data was analyzed with the significance level at α = 0.05. Results: The mean PH values were 4.17 ± 0.51 mm, 3.99 ± 0.61 mm, and 3.99 ± 0.62 mm, for the open contact group, complete papilla, and deficient papilla group, respectively. The PH values of the recorded sites among central incisors, lateral incisors, and canine were 4.13 ± 0.56 mm, 3.87 ± 0. 63 mm, and 4.07 ± 0.58 mm, respectively. No statistically significant differences of the PH values were determined between the above three tested groups as well as between the different sites (p > 0.05). The IDD values obtained from the complete papilla group were significantly lower than the other tested groups (p < 0.05). Conclusion: The contact point condition of upper anterior sextants may not influence the presence and dimension of the IP in periodontally healthy subjects.

10.
J Periodontol ; 91(11): 1429-1435, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32146722

RESUMO

BACKGROUND: The information of the association between residual alveolar bone height and mucosal thickening is sparse. This study aimed to explore the effect of maxillary molar periodontal status on sinus mucosal thickening using cone-beam computed tomography (CBCT). METHODS: One hundred ninety-four CBCT images were evaluated for the following parameters: age, sex, alveolar bone loss, maximum mucosal thickness (maxMT), minimum residual alveolar bone height (minRABH), and vertical infrabony pockets. The presence of mucosal thickening (maxMT > 2 mm) of the maxillary sinus was recorded. The parameters that could influence the dimensions of the maxillary sinus membrane were assessed. The data were analyzed using logistic regression, and multivariate linear regression with the significant level at α = 0.05. RESULTS: Mucosal thickening was present in 32% of the analyzed CBCT images and increased in frequency as the periodontal status of the corresponding molar progressed from mild (2.6%) to moderate (14.9%) to severe (75.5%). Mucosal thickness was significantly increased in cases of moderate (odds ratio = 5.73, P < 0.05) and severe (odds ratio = 82.06, P < 0.001) alveolar bone loss. Multivariate linear regression revealed that alveolar bone loss and minRABH had a statistically significant influence on maxMT (P < 0.05). CONCLUSIONS: Alveolar bone loss and minRABH were significantly associated with mucosal thickening of the maxillary sinus.


Assuntos
Seio Maxilar , Tomografia Computadorizada de Feixe Cônico Espiral , Tomografia Computadorizada de Feixe Cônico , Seio Maxilar/diagnóstico por imagem , Dente Molar/diagnóstico por imagem , Estudos Retrospectivos
11.
J Prosthet Dent ; 124(6): 647-652, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32057486

RESUMO

Tightening torques are often specified in implant dentistry, including for surgical procedures, testing implant stability, and attaching prosthetic components when screws are used. The mechanical torque limiting devices (MTLDs) commonly used are typically either a toggle-type or beam-type. The International Organization for Standardization (ISO) 6789 recommends MTLDs should be periodically tested to confirm the validity of their readings, and, where necessary, recalibrated if possible or replaced. The verification of the toggle-type MLTD has been previously published. This article describes a straightforward, in-office technique to verify a beam-type MTLD.


Assuntos
Implantes Dentários , Estresse Mecânico , Torque
12.
Int J Oral Maxillofac Implants ; 35(1): 135-140, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31923297

RESUMO

PURPOSE: Capturing implant position in impression-making procedures commonly involves transfer devices, such as implant impression copings and laboratory analogs. These components are intricately machined, including the lumen, and often include additional features for prevention of screw dislodgment. The Centers for Disease Control and Prevention recommends all surfaces in contact with human bodily fluid be disinfected with hospital-grade disinfectant. The ability of these components to harbor biologic contaminant material has not yet been determined, especially with regard to internal configuration, combined with the knowledge that many clinicians and laboratories use a spray disinfectant, which may limit disinfectant contact. The aim of this study was to determine the site and extent of contamination occurring on implant components following clinical impressions and laboratory procedures. MATERIALS AND METHODS: The study design included forensic staining and subsequent analysis of 60 used impression copings, 10 used laboratory analogs, and 10 new components as controls. RESULTS: Staining was found on 100% of impression copings used in vivo, indicating that biologic material had reached multiple sites on both internal and external surfaces of the components. Staining was also found on the internal aspect of used implant analogs, indicating transfer of biologic material from the impression coping and screw. None of the new control components presented staining at any site. Staining highlighted difficult areas to debride, particularly components with difficult or impossible access for cleaning and disinfection. CONCLUSION: Phloxine B staining indicated the ability of biologic material to reach all areas of the implant components. Having demonstrated the difficulty, sometimes impossibility, of accessing areas of these implant components, there is a need to develop protocols to reduce risk of potential transmission of infective material via implant components. Further study is warranted to determine the potential for transmission of infective material due to inadequate disinfection processes of implant componentry.


Assuntos
Implantes Dentários , Planejamento de Prótese Dentária , Adaptação Psicológica , Produtos Biológicos , Materiais para Moldagem Odontológica , Técnica de Moldagem Odontológica , Modelos Dentários , Humanos
13.
J Prosthodont ; 29(1): 87-93, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31702087

RESUMO

PURPOSE: To compare the internal fit and marginal discrepancy of acrylic resin interim crowns fabricated by different manufacturing methods, and to test the consistency of measuring marginal discrepancy and internal fit between different measuring techniques. MATERIALS AND METHODS: A dentoform mandibular left first molar was prepared for an all-ceramic crown. Thirty-six interim crowns were fabricated and divided into three groups (n = 12): group BAC (Bis-acrylic composite, fabricated manually), group CAM (CAD/CAM polymethylmethacrylate resin, milled), and group 3DP (3D printed methacrylic oligomers, printed). The internal fit of the interim crowns was evaluated by the silicone replica technique and by X-ray microcomputed tomography (µCT) technique. The marginal discrepancy of the interim crowns was evaluated by the vinyl polysiloxane (VPS) (Aquasil Ultra XLV) impression technique and by optical coherence tomography (OCT) technique. Data were statistically analyzed using ANOVA and Turkey tests at α = 0.05. Pearson correlation test was used to evaluate the correlation between the different measurement techniques and marginal discrepancy/internal fit. RESULTS: The manually fabricated interim crowns (group BAC) had significantly greater discrepancy of internal fit than did the digitally fabricated crowns (group CAM and group 3DP) measured by both silicone replica technique and µCT 2-dimensional (2D) image measurement. There were no statistically significant differences in the cement space volume values obtained by the µCT image technique between group BAC and group 3DP (p = 0.285). The coefficient of determination between the two volumetric measurement techniques was low (R2 = 0.30). For marginal discrepancy, the manually fabricated interim crowns had a wider absolute marginal discrepancy than both digitally fabricated groups (p < 0.05). In both the VPS impression and OCT assessment, there was no statistically significant difference between group CAM and group 3DP (p = 0.798 and 0.994, respectively). The coefficient of determination between the VPS impression and OCT techniques for marginal discrepancy measurement was low (R2 = 0.23). CONCLUSIONS: Digitally fabricated interim crowns (group CAM and group 3DP) had better internal fit and smaller marginal discrepancy than manually fabricated interim crowns (group BAC). For comparison of the different evaluation techniques, the silicone replica technique and µCT measurements had low correlation for internal fit assessment, as did the PVS impression and OCT techniques for marginal discrepancy test.


Assuntos
Adaptação Marginal Dentária , Planejamento de Prótese Dentária , Desenho Assistido por Computador , Coroas , Porcelana Dentária , Turquia , Microtomografia por Raio-X
14.
J Prosthet Dent ; 123(3): 524-528, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31307810

RESUMO

STATEMENT OF PROBLEM: A recently introduced hexalobular screw system allows for off-axial screw channel access. The screwdriver angle input torque relative to the screw axis output torque has not been established. PURPOSE: The purpose of this in vitro study was to evaluate the effect of maximum angulation on the abutment-implant screw connection and torque values for a hexalobular screw system and to determine how input versus output varies with the angle of the screwdriver. MATERIAL AND METHODS: Twenty angulated abutments attached to implant fixtures were tightened to the manufacturers' prescribed torque at 2 different input angles: 0 and 28 degrees off axial (n=10/group). Input and reverse torque values were recorded by using calibrated torque sensor devices and compared for significant differences by using the Mann-Whitney U test. Fifty hexalobular screws were subjected to screwdriver angle variations of 0, 10, 15, 25, and 28 degrees (n=10/group). The input torque (screw head) and output torque (screw body) were recorded. The Kruskal-Wallis rank sum test and the post hoc Dunn test were used for statistical analysis of the output torque (α=.05). RESULTS: Significant differences in mean reverse torque existed (P<.05) between the abutment-implant connection at the 2 angles measured. Significant differences were found at the output torque with varying angles of input torque (P<.05). No statistically significant differences were determined between 0 and 15 degrees. Torque values were significantly reduced for 25- and 28-degree angulations. CONCLUSIONS: Angle changes may affect the screw torque and ultimate preload. At extreme angulation beyond 15 degrees, screw performance may be affected and have clinical relevance in areas with high occlusal load.


Assuntos
Dente Suporte , Implantes Dentários , Parafusos Ósseos , Análise do Estresse Dentário , Torque
15.
J Prosthet Dent ; 123(3): 514-522, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31353116

RESUMO

STATEMENT OF PROBLEM: The adaptation of interim crowns made by subtractive and additive manufacturing has not been well investigated. PURPOSE: The purpose of this in vitro study was to evaluate the internal fit and marginal discrepancy of interim crowns made by different manufacturing methods. MATERIAL AND METHODS: A dentoform mandibular left first molar was prepared for a ceramic crown and scanned for the fabrication of 48 stereolithical resin dies and interim crowns. Group CAM included 16 ZCAD interim crowns made by computer-aided design and computer-aided manufacturing (CAD-CAM) technology; group 3DP, 16 NextDent MFH interim crowns made by digital light processing technology; and group APP, 16 Jet interim crowns manually made by using autopolymerizing acrylic resin and used as controls. The silicone replica technique was used to determine the internal discrepancy volume before definitive cementation. All crowns were cemented with Temp-Bond NE under a 50-N load and bench set for 10 minutes before microcomputed tomographic (µCT) scan assessment. The volume of cement space was measured by using the µCT scan 3-dimensional (3D) images, and gap distance at assigned locations was recorded by using the µCT scan 2-dimensional (2D) images. The marginal discrepancy was measured by the polyvinyl siloxane (PVS) impression technique and using a stereomicroscope. Data were analyzed by ANOVA and the Tukey honestly significant difference tests (α=.05). The association between different measuring techniques was analyzed by the Pearson correlation test. RESULTS: The gap distance between interim crowns and dies from all 3 groups measured by using the µCT scan 2D images ranged from 0.13 mm to 0.55 mm, with the highest value found at the central occlusal location in group APP. The total average gap distance values recorded for group APP were significantly higher than those for group CAM and group 3DP (P<.05). No significant differences were found in internal discrepancy and cement space volume between group CAM and group 3DP (P>.05). The Pearson correlation test showed a moderate correlation (r=0.69) between the silicone replica technique and the µCT scan technique in determining cement space volume. When the PVS impression technique was used to measure the marginal discrepancy, the mean values obtained from group APP were statistically significantly higher than those from group CAM and group 3DP (P<.05). No statistically significant difference in marginal discrepancy was found between group CAM and group 3DP (P=.70). CONCLUSIONS: Digitally fabricated interim crowns had better internal fit and smaller marginal discrepancy than manually constructed interim crowns. The silicone replica technique and µCT scan technique measurements had a moderate correlation in assessing the adaptation of cemented interim crowns.


Assuntos
Adaptação Marginal Dentária , Planejamento de Prótese Dentária , Desenho Assistido por Computador , Coroas , Porcelana Dentária
16.
J Prosthet Dent ; 123(3): 403-407, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31383530

RESUMO

Abutment screw loosening is still the most common complication reported with implant-supported crowns. One factor that contributes to screw loosening is not achieving the proper torque during the tightening process. Torque application and measurement is usually achieved by using one of the available types of mechanical torque wrench. Of these, the toggle wrench has been shown to produce erroneous readings, and regular testing is recommended. If it is inaccurate, it must be recalibrated or replaced. Calibration typically requires specialized instruments unavailable to most clinicians, so the device must be sent away. This article describes a straightforward, in-office, and inexpensive alternative for testing and recalibrating a toggle torque wrench.


Assuntos
Implantes Dentários , Parafusos Ósseos , Coroas , Dente Suporte , Prótese Dentária Fixada por Implante , Análise do Estresse Dentário , Torque
17.
J Prosthet Dent ; 124(2): 144-147, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31780106

RESUMO

Custom castable abutments with metal bases can be waxed and cast. However, the devesting stage may damage the milled metal base when airborne-particle abrasion is used. This may affect the abutment-to-implant joint, as well as the screw seat. Either of these can result in an improper connection that may produce a negative effect on joint performance. This technique describes the use of a computer-aided design and computer-aided manufactured zirconia protector cap and peg, placed before investing, that shield against airborne-particle damage during devesting.


Assuntos
Dente Suporte , Projeto do Implante Dentário-Pivô , Desenho Assistido por Computador , Titânio , Zircônio
18.
J Prosthet Dent ; 122(2): 153.e1-153.e8, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31326151

RESUMO

STATEMENT OF PROBLEM: Acrylic resin denture base materials, fabricated with either a traditional technique or computer-aided design and computer-aided manufacturing (CAD-CAM) technique, layered with different thicknesses of gingiva-shade composite resin may affect the strength of the definitive prostheses and have not been investigated. PURPOSE: The purpose of this in vitro study was to assess the flexural strength of acrylic resin denture base materials modified by layering different thicknesses of gingiva-shade composite resin. MATERIAL AND METHODS: Two denture acrylic resins, heat-polymerized type (Lucitone 199) and CAD-CAM prepolymerized type (AvaDent) polymethyl methacrylate (PMMA) resin, were used as the base materials. Three-millimeter-thick specimens were fabricated and prepared according to the ISO 1567 and ISO 20795-1:2013 and were used as the controls. A proprietary gingiva-shade composite resin (GRADIA gum shades) was used to replace different thicknesses (0.5 mm, 1.0 mm, and 1.5 mm) of the denture base materials, giving 4 groups for each tested material (n=16). A 3-point loading test was conducted by using a universal testing machine and a custom fixture with a crosshead speed of 5 mm/min. The maximum fracture loads were recorded, and ultimate flexural strength values were calculated. The collected data were statistically analyzed with ANOVA and the Tukey honestly significant difference (HSD) tests (α=.05). Representative fractured specimens were examined under a stereomicroscope at ×20 magnification and a scanning electron microscope to determine the interface and fracture patterns. RESULTS: The mean ±standard deviation of ultimate flexural strengths for the heat-polymerized acrylic resin specimens ranged from 94.79 ±9.89 MPa to 40.34 ±12.79 MPa, and that of the CAD-CAM prepolymerized acrylic resin ranged from 125.98 ±7.96 MPa to 64.16 ±20.77 MPa. Acrylic resin denture base materials after layering with gingiva-shade composite resin had a significantly lower mean fracture load than the controls (P<.05). The Tukey HSD test revealed that the control groups had significantly higher flexural strength values compared with the other tested specimens within each denture acrylic resin group layered with gingiva-shade composite resin (P<.05). The SEM images displayed brittle fracture exhibiting well-defined, flat, compact, and organized surface fractures. CONCLUSIONS: The flexural strengths of CAD-CAM prepolymerized acrylic resins were higher than those of the heat-polymerized denture acrylic resins. The flexural strengths of all 3 thicknesses of the CAD-CAM prepolymerized acrylic resins were greater than 65 MPa.


Assuntos
Bases de Dentadura , Polímeros , Resinas Compostas , Análise do Estresse Dentário , Gengiva , Teste de Materiais , Polimetil Metacrilato
19.
Artigo em Inglês | MEDLINE | ID: mdl-31171483

RESUMO

OBJECTIVE: The aim of this study was to compare root surface area (RSA) measurements of single-root teeth in a sheep mandible based on cone beam computed tomography (CBCT) with measurements made with an optical scanner. STUDY DESIGN: Eight anterior teeth of a sheep cadaver mandible were scanned in situ by using CBCT with 3 different exposure parameters, followed by treatment with smoothing software. The teeth were then extracted and scanned individually with an optical scanner. Three-dimensional digital models of the teeth were reconstructed on the basis of CBCT and optical scanner data. RSA data were calculated, and an equivalence test was used to statistically compare the measurements with significance of difference established at α = 0.05. RESULTS: The means of the differences between RSA measurements from CBCT and optical scanning ranged from 0.33% to 3.01%. There were no statistically significant differences between the 2 methods. The smoothing parameters for good fitness of the linear regression were determined to be 0.8 for the smooth factor, 8 for iterations, and 0 for compensate shrinkage. CONCLUSIONS: The proposed CBCT technique to measure RSA is feasible. RSA data obtained from CBCT in situ are as accurate as optical scanner measurements ex vivo.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Raiz Dentária , Animais , Imageamento Tridimensional , Mandíbula/diagnóstico por imagem , Cintilografia , Ovinos , Software , Raiz Dentária/diagnóstico por imagem
20.
Cancer Lett ; 460: 75-85, 2019 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-31247272

RESUMO

Accumulating experimental evidence has shown that the aberrant expression of microRNAs (miRNAs) is involved in the development and progression of human cervical cancer. Previously, we identified miR-182 as an oncomiRNA in cervical cancer. However, the mechanism by which miR-182 is regulated and the interaction between human papillomavirus (HPV) and miR-182 in cervical cancer development remains unknown. In the present study, we explored the link between HPV E7 and miR-182 and verified that high-risk HPV E7 upregulated miR-182 expression through TGF-ß/Smad4 signaling pathway in cervical cancer. By contrast, low-risk HPV E7 did not affect the expression of TGF-ß and miR-182. Mechanistically, as high-risk HPV E7 bound to pRb, E2F was released from the complex and bound to the TGF-ß promoter region, resulting in TGF-ß overexpression. Furthermore, the Smad4 signaling pathway was activated upon TGF-ß overexpression, which led to an interaction between Smad4 and the miR-182 promoter region, subsequently inducing the upregulation of miR-182 in both cervical cancer cells and the surrounding normal cells. In conclusion, this newly identified high-risk HPV E7/TGF-ß/miR-182 regulatory network might inform the development of specific therapeutic strategies for cervical cancer.


Assuntos
Proteínas de Ligação a DNA/metabolismo , MicroRNAs/metabolismo , Proteínas Oncogênicas Virais/metabolismo , Papillomaviridae/metabolismo , Proteínas E7 de Papillomavirus/metabolismo , Proteína Smad4/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/virologia , Adulto , Animais , Sítios de Ligação , Técnicas de Cocultura , Proteínas de Ligação a DNA/genética , Fatores de Transcrição E2F/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Células HeLa , Interações Hospedeiro-Patógeno , Humanos , Camundongos Endogâmicos BALB C , Camundongos Nus , MicroRNAs/genética , Pessoa de Meia-Idade , Proteínas Oncogênicas Virais/genética , Papillomaviridae/genética , Papillomaviridae/patogenicidade , Proteínas E7 de Papillomavirus/genética , Fosforilação , Regiões Promotoras Genéticas , Proteína do Retinoblastoma/metabolismo , Transdução de Sinais , Proteína Smad4/genética , Fator de Crescimento Transformador beta/genética , Regulação para Cima , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/patologia
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