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The International Journal of... Sep 2023To investigate the influence of occlusal interference using finite element analysis (FEA).
PURPOSE
To investigate the influence of occlusal interference using finite element analysis (FEA).
MATERIALS AND METHODS
The FEA model designed for this study centered on an all-ceramic, bilayered, fixed partial denture (FPD) retained on the maxillary first premolar and first molar, with the second premolar replaced by a pontic. The surrounding structures-such as the neighboring teeth, antagonists, and periodontium-were modeled. Four different loading cases were designed at occlusal interferences of 0, 8, 12, and 24 μm and were loaded by a simulated bite force of 300 N. Principal and von Mises stresses, as well as strain, were evaluated for all included structures.
RESULTS
For interferences of 12 and 24 μm, failure-relevant tensile stresses in the veneering layer were observed at the occlusal surfaces. Stress found in the zirconia FPD did not reach fatigue or flexural strength for any test load.
CONCLUSION
Peak tensile stress was observed in close proximity to occlusal contact points, increasing with increasing occlusal interference. The FEA results suggest that the majority of occlusal stress is absorbed by the deformation of the periodontal ligament. Framework failure caused by the simulated interferences was not expected. Surface defects may ultimately lead to failure due to fracture or chipping, especially in cases of weaker ceramics or veneering.
Topics: Occlusal Adjustment; Finite Element Analysis; Bite Force; Ceramics; Denture, Partial, Fixed
PubMed: 37699184
DOI: 10.11607/ijp.7178 -
Oral and Maxillofacial Surgery Jun 2024The aim of this study is to evaluate the relationship between the inclination/impaction depth and root proximity to the inferior alveolar canal/lingual plate on a...
PURPOSE
The aim of this study is to evaluate the relationship between the inclination/impaction depth and root proximity to the inferior alveolar canal/lingual plate on a millimeter scale using CBCT scans.
METHODS
340 CBCT scans of the mandibular third molar (M3) of 219 patients were evaluated for this cross-sectional study. After adjustment of the 3D orientation of the individual's jaws, the study variables including the angulation between M3 and second molar (M2)/occlusal plane (OP), and the distance of mesial (M)/distal (D) roots of M3 from the inferior alveolar canal (IAC) and lingual plate (LP) were measured. Winter's classification was used for the specification of teeth angulation. The vertical position of each M3 was then evaluated using the 3D view window (based on Pell & Gregory classification). The Spearman correlation coefficient was used for reporting the correlation between quantitative variables. The One-way ANOVA test and the Welch analysis were used for inter-group comparisons. Finally, a multivariant analysis of variances was performed.
RESULTS
Most third molars had a mesioangular inclination (52.1%), and vertical inclination (25.9%) was in second place. There was no significant correlation between angulation and age or the D/LP. A strong positive correlation between M3:M2 and M3:OP was observed (0.983). Furthermore, there was a weak negative correlation between M/IAC or M/LP and angulation (- 0.16 and - 0.13, respectively). Concerning Winter's classification, the relationship between D/IAC and angulation was statistically significant (P = 0.003). Furthermore, teeth in position A had lesser inclination compared to those with B or C positions. Multivariate analysis revealed that there was no statistically significant relationship between particular combinations of inclination-impaction depth and proximity of the M3 roots to the IAC or LP (P = 0.211).
CONCLUSIONS
The findings of the current study revealed that there is a strong correlation between M3:M2 and M3:OP. The D/IAC was the only variable that had a significant relationship with the angulation of these teeth. Moreover, the roots of horizontally inclined teeth with position A were the closest to the LP and the farthermost to the IAC.
Topics: Humans; Molar, Third; Mandible; Cross-Sectional Studies; Cone-Beam Computed Tomography; Adult; Female; Male; Tooth, Impacted; Young Adult; Adolescent; Middle Aged; Imaging, Three-Dimensional; Tooth Root
PubMed: 37620734
DOI: 10.1007/s10006-023-01178-y -
The Journal of Prosthetic Dentistry Aug 2023The volume of occlusal adjustment of digital occlusal devices designed with different digital occlusal articulators is unknown.
Comparative evaluation of the volume of occlusal adjustment of repositioning occlusal devices designed by using an average value digital articulator and the jaw movement analyzer.
STATEMENT OF PROBLEM
The volume of occlusal adjustment of digital occlusal devices designed with different digital occlusal articulators is unknown.
PURPOSE
The purpose of this clinical study was to evaluate and compare the clinical efficacy and volume of occlusal adjustment of digital occlusal devices designed by using an average value digital articulator and the jaw movement analyzer (JMA).
MATERIAL AND METHODS
Thirty participants were randomly divided into 2 groups, an Average value group and a JMA group, with 15 participants in each group. The centric relation position of the participants was determined by an experienced investigator with the aid of a leaf gauge. An intraoral scanner (TRIOS 3) was used to obtain digital scans of the maxillary and mandibular dentition and the maxillomandibular relationship record in the centric relation position. Personalized articulator parameters of participants in the JMA group were obtained by using a JMA (JMAnalyser). Different articulator parameters were used to fabricate an occlusal device in a denture design software program (exocad DentalCAD). The surface of the occlusal device was coated with a dental optical spray and then scanned by using a laboratory scanner (Kavo LS3). The process was repeated after the occlusal device was adjusted. The files of the 2 scans were imported into a reverse engineering software program, and the root mean square (RMS) values were obtained by best-fit alignment and 3-dimensional comparison. The Shapiro-Wilk normality test and homogeneity of variance test were performed, and t tests were used to evaluate differences in the RMS values between the groups (α=.05).
RESULTS
The experimental data were generally normally distributed (P>.05). No statistically significant difference was found between the RMS values of the Average and the JMA groups (P>.05).
CONCLUSIONS
No significant difference in the volume of occlusal adjustment was found when using occlusal devices made by using the digital average articulator or the JMA, suggesting that either method can be used to program articulators for the fabrication of occlusal devices.
PubMed: 37537106
DOI: 10.1016/j.prosdent.2023.06.018 -
Journal of Prosthodontics : Official... Aug 2023This in vitro study aimed to evaluate the effects of restorative materials and scanning aid conditions on the accuracy and time efficiency of intraoral scans.
PURPOSE
This in vitro study aimed to evaluate the effects of restorative materials and scanning aid conditions on the accuracy and time efficiency of intraoral scans.
MATERIALS AND METHODS
Identical anatomic contour crowns were fabricated using the following materials: hybrid ceramic, 3 mol% yttria-stabilized tetragonal zirconia, 4 mol% yttria-partially stabilized zirconia, 5 mol% yttria-partially stabilized zirconia, cobalt-chromium (Co-Cr), resin, lithium disilicate, and feldspathic ceramic. The models were digitized and analyzed for accuracy (n = 10) under three scanning aid conditions (powder-based, liquid-based, and none). Additionally, the effect of metal restorations on the scan accuracy of other crowns was investigated. The scan time for complete arches was also recorded. One-way analysis of variance, Welch analysis of variance, and post-hoc comparison or independent t-tests were used for trueness analysis, and the F-test was used to examine precision (α = 0.05).
RESULTS
Significant differences were observed in the trueness of the different restorative materials under the no-scanning aid condition (P < 0.05). In contrast, no statistically significant difference among the groups was observed with the powder- or liquid-based scanning aid. For each restorative material, the no-scanning aid condition showed significantly lower trueness than that with powder- or liquid-based scanning aids. The presence of a Co-Cr crown did not affect the trueness of other restorations in the arch. The scan time efficiency significantly increased on applying a powder- or liquid-based scanning aid.
CONCLUSIONS
Using a scanning aid was effective to improve the scan accuracy of the tested restorative materials and scan time efficiency. Applying scanning aids to existing intraoral restorations can help improve prosthesis quality and reduce the need for clinical adjustment at the occlusal or proximal contacts.
Topics: Powders; Dental Materials; Ceramics; Crowns; Computer-Aided Design
PubMed: 37421209
DOI: 10.1111/jopr.13727 -
The Journal of Prosthetic Dentistry Jul 2023In the digital workflow of complete denture fabrication, one solution for producing computer-aided design and computer-aided manufacturing dentures has been to mill the...
In the digital workflow of complete denture fabrication, one solution for producing computer-aided design and computer-aided manufacturing dentures has been to mill the denture teeth and base separately and then bond them together. The correct bonding of the denture teeth and base is important to reproduce the designed occlusion in the definitive prosthesis. A novel technique is described to assist in the accurate positioning of denture teeth on the denture base by constructing auxiliary positioning slots on the denture base and auxiliary positioning posts on the denture teeth. The technique can assist in accurately assembling CAD-CAM milled complete dentures and may shorten chairside time by reducing clinical occlusal adjustment.
PubMed: 37414596
DOI: 10.1016/j.prosdent.2023.05.017 -
Journal of Esthetic and Restorative... Dec 2023To evaluate the volumetric changes on occlusal surface of computer-aided design and computer-aided manufacturing (CAD-CAM) occlusal devices fabricated following a fully...
OBJECTIVE
To evaluate the volumetric changes on occlusal surface of computer-aided design and computer-aided manufacturing (CAD-CAM) occlusal devices fabricated following a fully digital workflow after occlusal adjustment, compared to those fabricated with an analog workflow.
MATERIALS AND METHODS
Eight participants were included in this clinical pilot study, receiving two different occlusal devices fabricated with two different workflows, fully analog and fully digital. Every occlusal device was scanned before and after the occlusal adjustments to compare the volumetric changes using a reverse engineering software program. Moreover, three independent evaluators assessed a semi-quantitative and qualitative comparison using visual analog scale and dichotomous evaluation. The Shapiro-Wilk test was performed to validate normal distribution assumption, and a dependent t-Student test for paired variables was used to determine statistically significant differences (p-value < 0.05).
RESULTS
The root mean square value was extracted from the 3-Dimensional (3D) analysis of the occlusal devices. The average values of the root mean square were higher for the analogic technique (0.23 ± 0.10 mm) than the digital technique (0.14 ± 0.07 mm) but the differences were not statistically significant (paired t-Student test; p = 0.106) between the two fabrication techniques. The semiquantitative visual analog scale values between the impression for the digital (5.08 ± 2.4 cm) and analog (3.80 ± 3.3 cm) technique were significant (p < 0.001), and statistically significant differences values were assessed for evaluator 3 compared to the other evaluators (p < 0.05). However, the three evaluators agreed on the qualitative dichotomous evaluation in 62% of the cases, and at least two evaluators agreed in 100% of the evaluations.
CONCLUSIONS
Occlusal devices fabricated following a fully digital workflow resulted in fewer occlusal adjustments, as they could be a valid alternative to those fabricated following an analog workflow.
CLINICAL SIGNIFICANCE
Fabricated occlusal devices following a fully digital workflow could have some advantages over analog workflow such reduce occlusal adjustments at delivery appointment, which can result in reduced chair time and therefore increased comfort for the patient and clinician.
Topics: Humans; Occlusal Splints; Pilot Projects; Occlusal Adjustment; Computer-Aided Design; Workflow; Dental Prosthesis Design
PubMed: 37395327
DOI: 10.1111/jerd.13080 -
BMC Oral Health Jun 2023This study is to investigate the referral pattern and treatment modality of dentists in the management of peri-implant diseases between periodontists and...
OBJECTIVES
This study is to investigate the referral pattern and treatment modality of dentists in the management of peri-implant diseases between periodontists and non-periodontist dentists (NPDs).
MATERIALS AND METHODS
A total of 167 validated questionnaires were obtained from periodontists and NPDs, who had experience of placing implants for at least one year. Question I to IV asked how the dentist would respond if a patient came for treatment of their peri-implant diseases with four different scenarios according to resource of patient and disease severity. For each Scenario, dentists also replied which treatment procedures they would use if they decide to treat the patient.
RESULTS
Periodontal training, resource of patient, and disease severity were shown to significantly influence the referral pattern and treatment modality in the management of peri-implant disease (p < 0.05). Periodontists were more likely to use variable treatment procedures, including occlusal adjustment (OR = 2.283, p < 0.01), oral hygiene instruction (OR = 3.751, p < 0.001), topical antiseptic agent (OR = 2.491, p < 0.005), non-surgical mechanical therapy (OR = 2.689, p < 0.001), surgical therapy (OR = 2.009, p < 0.01), and remove implant (OR = 3.486, p < 0.001) to treat peri-implant diseases, compared to NPDs.
CONCLUSION
The periodontal specialty training, resource of patient, and disease severity significantly influenced the referral pattern and treatment modality of dentist treating an implant diagnosed with peri-implant disease. This study also highlighted the importance of educating basic periodontal and peri-implant disease-related knowledge to all dentists regularly performing dental implant treatments.
CLINICAL RELEVANCE
Peri-implant diseases are highly prevalent among patients with dental implants. Periodontal specialty training could enhance using variable treatment procedures to treat peri-implant diseases for dentists.
Topics: Humans; Peri-Implantitis; General Practice, Dental; Dental Implants; Dentists; Referral and Consultation
PubMed: 37370067
DOI: 10.1186/s12903-023-03135-3 -
Oral Health & Preventive Dentistry Jun 2023This review aimed to highlight the aetiology and risk factors of food impaction along with the treatment in each case. (Review)
Review
PURPOSE
This review aimed to highlight the aetiology and risk factors of food impaction along with the treatment in each case.
MATERIALS AND METHODS
A search was conducted in PubMed from 1947 to March 28, 2023. The search terms utilised included (food impaction) OR (interdental impaction). No filter was applied. Articles related to the classification, aetiology, treatment, and associated factors of food impaction in dentistry and published in English or with an abstract in English were selected.
RESULTS
A total of 72 articles were included in the review, which revealed the variety and complexity of aetiological factors and treatment of food impaction in dentistry, as well as the heterogeneity of previous studies. Based on the aetiology, different treatment plans and management should be considered.
CONCLUSION
This review indicated the need to identify the pathology of food impaction before treatment. Considering the causal factors of food impaction - including proximal contact loss, occlusal disharmony, morphological deformity, positional abnormality, and interdental papillae loss - different management approaches such as restoration, occlusal adjustment, orthodontic, nonsurgical or surgical treatment could be applied. Further clinical and experimental research is warranted to address the prevention and treatment of food impaction in dentistry.
Topics: Humans; Gingiva; Dentistry
PubMed: 37345582
DOI: 10.3290/j.ohpd.b4172837 -
Journal of Prosthodontic Research Jan 2024Purpose Temporomandibular disorders (TMDs) are frequent stomatological disorders. However, their treatment is controversial. Therefore, we compared the efficacy of... (Meta-Analysis)
Meta-Analysis
Purpose Temporomandibular disorders (TMDs) are frequent stomatological disorders. However, their treatment is controversial. Therefore, we compared the efficacy of combination therapy (splint therapy along with physiotherapy, manual therapy, and counseling) with physiotherapy, manual therapy, and counseling alone. The extent of mouth opening and pain perception were the outcomes.Study selection Systematic searches for English publications were performed using four major literature databases (Cochrane Library, EMBASE, PubMed, and Web of Science). We included randomized controlled trials. We calculated mean differences with 95% confidence interval (CI) for pain perception and maximum mouth opening (MMO) for the two groups. The Hartung-Knapp adjustment was used for cases comprising at least five studies.Results Six articles were included in the pain perception category, and four were reviewed for MMO at baseline. Four articles assessed pain perception, and two assessed MMO at 1 month. Five articles were analyzed upon comparing pain perception at baseline and 1-month follow-up. The mean difference was -2.54 [95% CI: -3.38; to -1.70] in the intervention group and -2.33 [95% CI: -4.06; to -0.61] in the control group. Two articles were analyzed upon comparing MMO at baseline and 1-month follow-up. The mean difference in the intervention group was 3.69 [95% CI: -0.34; 7.72], whereas that in the control group was 3.62 [95% CI: -3.43; 10.67].Conclusions Both therapies can be used in the management of myogenic TMD. Due to the marginal differences between the baseline and 1-month values, our results could not confirm the efficacy of combination therapy.
Topics: Humans; Splints; Treatment Outcome; Randomized Controlled Trials as Topic; Temporomandibular Joint Disorders; Pain
PubMed: 37286515
DOI: 10.2186/jpr.JPR_D_22_00264 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Jun 2023This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using... (Comparative Study)
Comparative Study
OBJECTIVES
This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using the mandibular movement track and the movement parameters of a virtual articulator.
METHODS
Twenty-two participants were recruited. Digital casts of the maxillary and mandibular arches were obtained using an intraoral scanner, and the jaw registration system was used to record the data of the mandibular movement track and the movement parameters of the articulator. Four kinds of restorations with 0.3 mm occlusal interferences were designed with dental design software. In particular, single crowns were designed for teeth 44 and 46, whereas three-unit bridges were designed for teeth 44-46 and 45-47, and the corresponding natural teeth were virtually extracted. Virtual adjustment of the restorations was performed using two dynamic occlusal recordings, namely, the mandibular movement track and the movement parameters of the virtual articulator. A reverse-engineering software was used to measure the root-mean-square of the three-dimensional deviation of the occlusal surfaces between natural teeth and the adjusted restorations. The differences between the two methods of virtual-occlusion adjustment were compared and analyzed.
RESULTS
For the same group of restorations, the three-dimensional deviation of the mandibular movement track group were lower than those of the virtual articulator group, and the differences were statistically significant (<0.05). For the four groups of restorations adjusted by the same method, the three-dimensional deviation of the 46-tooth single crown was the largest and the smallest three-dimensional deviation was that of the 44-tooth single crown. Statistical differences existed between the 44-tooth single crown and the other groups (<0.05).
CONCLUSIONS
For the occlusal design of posterior single crown and three-unit bridge, the mandibular movement track could be a more effective approach to virtual occlusal adjustment than the movement parameters of the virtual articulator.
Topics: Humans; Mouth, Edentulous; Occlusal Adjustment; Jaw Relation Record; Dental Articulators; Software
PubMed: 37277790
DOI: 10.7518/hxkq.2023.2022452