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Clinical Oral Investigations Jul 2021To evaluate the precision of aligner (Invisalign®) treatment with the current material (SmartTrack®) in achieving expansion or contraction of the maxilla and occlusal...
OBJECTIVES
To evaluate the precision of aligner (Invisalign®) treatment with the current material (SmartTrack®) in achieving expansion or contraction of the maxilla and occlusal contacts as simulated in the proprietary planning software (ClinCheck®, CC).
MATERIALS AND METHODS
Thirty patients thus treated were retrospectively evaluated. Four maxillary models were analyzed per patient: a pretreatment model, a scan-based CC model, a posttreatment clinical model, and a CC model reflecting the treatment outcome as initially simulated. Thirteen transverse parameters were measured on each model separately by two investigators. Occlusal contacts were also analyzed.
RESULTS
The measuring method was validated by both investigators arriving at similar results for the effectiveness by which the simulated treatment goals had been clinically achieved. Significant differences (p < 0.05; Wilcoxon signed-rank test) were observed for transfer precision from the casts to the planning software and between the simulated and clinical outcomes. Intense occlusal contacts in the simulations materialized less common (≈ 2%) than ideal contacts (≈ 60%) in the clinical outcomes.
CONCLUSIONS
The effectiveness of achieving the simulated transverse goals was 45% and was generally not found to be better with SmartTrack® than with the previously used Ex30® material. Out of 100 simulated occlusal contacts, 40 will never materialize, and achieving around 60 will adequately ensure a clinically favorable contact pattern.
CLINICAL RELEVANCE
With the caveat that any overcorrection will to some extent reduce the precision, it seems perfectly possible to make deliberate use of overcorrection in current aligner therapies for transverse maxillary expansion or contraction.
Topics: Humans; Malocclusion; Maxilla; Occlusal Adjustment; Orthodontic Appliances, Removable; Palatal Expansion Technique; Retrospective Studies
PubMed: 33474622
DOI: 10.1007/s00784-021-03780-4 -
BDJ Open May 2023To measure the required clinical time and volume of occlusal adjustment when the maxillary cast is positioned in a virtual articulator using one of three methods:...
OBJECTIVE
To measure the required clinical time and volume of occlusal adjustment when the maxillary cast is positioned in a virtual articulator using one of three methods: digitization of a facebow-mounted mechanical articulator (group A), virtual Bonwill triangle (group B) or a 3D face scan (group F).
MATERIALS AND METHODS
In this randomized, triple-blind, crossover trial; 11 participants were enrolled. Every participant had one molar indicated for a single crown restoration. Three crowns were designed and milled for every participant molar totaling 33 crowns. Each of the three crowns was fabricated with the participant's casts virtually mounted utilizing a different method. An impression was taken of the crown in place before occlusal adjustment. The occlusal adjustment was then performed and timed with the three crowns in the different groups. After the occlusal adjustment, an impression of the adjusted crown was taken. The pre-adjustment and post-adjustment impressions were digitally superimposed and the volume difference was measured. The Kruskal-Wallis test was used to compare the groups.
RESULTS
Group A showed the shortest mean adjustment time (3:44.59 ± 3:39.07) followed by group F (4:30.09 ± 2:01.50) and group B (4:35.30 ± 2:32.33). The mean adjustment volume for group A was (28 ± 19.1 mm) followed by group F (30.5 ± 18.8 mm) and group B (40.6 ± 29.5 mm). Different virtual mounting methods had no statistically significant effect on adjustment time (P-value = 0.538) or adjustment volume (P-value = 0.490).
CONCLUSIONS
A simplified approach in virtual articulator mounting appears to be justified in the construction of a single full-coverage prosthesis. Added labor, time and cost of more elaborate virtual mounting methods seem to be counterproductive.
PubMed: 37164989
DOI: 10.1038/s41405-023-00146-8 -
Frontiers in Endocrinology 2022Occlusal support was proved to be associated with type 2 diabetes. Our aim was to investigate the association between the Eichner index and the prevalence of type 2...
Occlusal support was proved to be associated with type 2 diabetes. Our aim was to investigate the association between the Eichner index and the prevalence of type 2 diabetes. We included 715 participants with oral health examinations in the Shanghai Aging Study. The occlusal support status was determined by the number of functional occlusal support areas and Eichner index classifications. Those with fasting plasma glucose ≥126 mg/dL and/or hemoglobin A1c ≥6.5% and/or current medications for type 2 diabetes with relevant medical history were diagnosed with type 2 diabetes. Multiple logistic regression models were used to analyze the relationship between occlusal support status and type 2 diabetes. The average age of 715 participants was 73.74 ± 6.49 years old. There were 84 diabetics with 1.71 occlusal supporting areas on average. Seven hundred and fifteen participants were divided into 3 groups according to Eichner classifications: Eichner group A with 4 occlusal functional areas, Eichner group B with 1-3 occlusal functional areas or 0 area with anterior occlusal contact, and Eichner group C with no functional occlusal contact. Blood glucose level was significantly lower in participants of Eichner group A compared to those in group B or C. The ordinal logistic regression showed more occlusal supporting areas were significantly associated with less type 2 diabetes cases with an Odds Ratio(OR) of 0.253(95%CI 0.108-0.594) after adjusting covariates. Participants in Eichner group A had a significantly much lower OR of 0.078 for type 2 diabetes (95%CI 0.009-0.694) compared to those in Eichner group C after adjustment. The number of functional occlusal support areas might be inversely related to the blood glucose level and the prevalence of type 2 diabetes.
Topics: Aged; Aged, 80 and over; Aging; Blood Glucose; China; Diabetes Mellitus, Type 2; Humans
PubMed: 36004339
DOI: 10.3389/fendo.2022.934274 -
Journal of Prosthodontic Research Jul 2016Dentists may encounter patients who present with a sense of a malocclusion but in whom no objective findings can be detected. For the patient who insists that there is... (Review)
Review
PURPOSE
Dentists may encounter patients who present with a sense of a malocclusion but in whom no objective findings can be detected. For the patient who insists that there is occlusal discomfort, in the absence of evidence some dentists elect to perform an occlusal adjustment that not only fails to alleviate symptoms, and may, in fact, exacerbate the discomfort. The patient-dentist relationship is then likely compromised because of a lack of trust.
STUDY SELECTION
In 2011, the Clinical Practice Guidelines Committee of the Japan Prosthodontic Society formulated guidelines for the management of occlusal discomfort. When formulating clinical practice guidelines, the committee bases their recommendations on information derived from scientific evidence. For "occlusal dysesthesia," however, there are an insufficient number of high-quality papers related to the subject. Therefore, a consensus meeting was convened by the Japan Prosthodontic Society to examine evidence in the Japanese- and English-language literature and generate a multi-center survey to create an appropriate appellation for this condition.
RESULTS
As a result of the consensus meeting and survey findings, this condition may be justifiably termed "occlusal discomfort syndrome."
CONCLUSIONS
The Japan Prosthodontics Society believes that identification of an umbrella term for occlusal discomfort might serve as a useful guide to formulating clinical practice guidelines in the future. This position paper represents summary findings in the literature combined with the results of a multicenter survey focused on dental occlusal treatment and the condition of patients who present with occlusal discomfort syndrome.
Topics: Adult; Aged; Disease Progression; Female; Humans; Japan; Male; Malocclusion; Middle Aged; Occlusal Adjustment; Practice Guidelines as Topic; Prosthodontics; Sensation; Syndrome
PubMed: 26868189
DOI: 10.1016/j.jpor.2015.11.002 -
Journal of Advanced Pharmaceutical... Nov 2022Occlusal analysis is important to analyze any disharmony in occlusion. Atraumatic dental occlusion leads to evolution of T-scan. T-scan gives a valuable procedure for...
Occlusal analysis is important to analyze any disharmony in occlusion. Atraumatic dental occlusion leads to evolution of T-scan. T-scan gives a valuable procedure for clinical assessment and perception of occlusal problems. T-scan can also be used in periodontitis patients for checking the occlusal pattern. Occlusal problems and periodontal disease relationship remains controversial. Further research is needed to determine whether occlusal adjustment is necessary for periodontal treatment. The main aim of the study was to assess the occlusal pattern using T-scan in periodontitis patients. Thirty periodontitis subjects were taken and checked for occlusion using T-scan. The subject's age group was 35-55 years. The study included 15 males and 15 females. Plaque index, gingival index, attachment loss, probing depth, centric occlusion (CO), protrusion, right lateral, and left lateral were the parameters studied. Occlusal adjustments were needed to decrease and dissipate the abnormal occlusal forces. The significance of statistical tests for various movements are as follows: CO (right and left) ( = 0.077) > 0.05; protrusion (right and left) ( = 0.09) > 0.05; left side lateral (right side and left side) ( = 0.01) < 0.05; right lateral (right side and left side) ( = 0.00) < 0.05. CO and protrusion (right, left) for males and females are not significant. Left lateral and right lateral (right, left) for males and females were significant. The T-scan manages adequate specificity and sensitivity. Hence, these act as a distinctive tool for diagnosis and better unreliable when used intraorally. The T-scan method is definitely a valuable tool for examining and evaluating the occlusal contacts during maximal intercuspation.
PubMed: 36643123
DOI: 10.4103/japtr.japtr_225_22 -
Journal of Clinical Medicine Jan 2023The inaccurate maxillomandibular relationship of virtual casts following alignment by the vestibular scan may result in intersection (intermesh penetration) between...
BACKGROUND
The inaccurate maxillomandibular relationship of virtual casts following alignment by the vestibular scan may result in intersection (intermesh penetration) between opposing dental arch surfaces. Intersection occurs at short interocclusal distances in the occlusal contact area (OCA) and may result in infra-occluded definitive restorations. The purpose of this clinical study was to compare initial (by the proprietary scanner software) and new alignments (by a standalone 3D software) of virtual casts regarding OCA and intersection failure. New alignments aimed to rectify intersections by refinement of occlusal contacts.
MATERIAL AND METHODS
The virtual casts of 30 patients following digital and conventional impression-taking were analyzed, which were acquired for single implant restoration in the posterior site. Digital impressions were performed by both IOS 1 (3M True Definition) and IOS 2 (TRIOS 3), either as complete- or partial-arch scans, respectively. Mounted gypsum casts were digitized as complete-arch by a laboratory scanner (LS) in enabled and disabled mode to avoid intersection [LS (+)/LS (-)]. All virtual casts were newly aligned by a 3D software. The difference of the OCA and the area of intersection were calculated for initial and new alignments, using interocclusal distance ranges of 0-100 μm, 0-10 μm or <0 μm (=intersection). The difference of the OCA was compared using a linear mixed model. The distribution of occlusal contact points per modality and alignment was assessed independently by three observers and estimated by inter- and intraclass correlation (ICC) coefficients.
RESULTS
Virtual casts following initial alignment demonstrated intersections irrespective of the modality. The mean area of the intersection was most for IOS 2 (79.23 mm), followed by IOS 1 (48.28 mm), LS (-) (2.77 mm), and LS (+) (2.01 mm) in partial-arch scans. Complete-arch scans demonstrated an area of intersection of 70.63 mm for IOS 1 followed by 65.52 mm (IOS 2), 6.13 mm [LS (-)] and 2.76 mm [LS (+)]. Newly aligned scans showed no intersections. The overall distribution of occlusal contact points demonstrated moderate reliability (ICC 0.63). Good reliability could be observed (ICC 0.9) for LS (-) scans.
CONCLUSIONS
Intersections in the area of occlusal contact points are a phenomenon restricted to virtual casts, which should be considered in CAD/CAM. Initial alignments of LS are less affected by this virtual phenomenon, and contact points may be more distinct according to their anatomic region compared to IOS. Furthermore, intersections can be rectified in a 3D software by adjustment of the maxillomandibular relationship.
PubMed: 36769645
DOI: 10.3390/jcm12030996 -
The Journal of Advanced Prosthodontics Jun 2019The aim of this study was to evaluate the effect of occlusal adjustments on the surface roughness of yttria-tetragonal zirconia polycrystal (Y-TZP) and wear of opposing...
PURPOSE
The aim of this study was to evaluate the effect of occlusal adjustments on the surface roughness of yttria-tetragonal zirconia polycrystal (Y-TZP) and wear of opposing artificial enamel.
MATERIALS AND METHODS
Twenty-five Y-TZP slabs from each brand (Lava, 3M and Bruxzir, Glidewell Laboratories) with different surface conditions (Control polished - CPZ; Polished/ground - GRZ; Polished/ground/repolished - RPZ; Glazed - GZ; Porcelain-veneered - PVZ; n=5) were abraded (500,000 cycles, 80 N) against artificial enamel (6 mm diameter steatite). Y-TZP roughness (in µm) before and after chewing simulation (CS) and antagonist steatite volume loss (in mm) were evaluated using a contact surface profilometer. Y-TZP roughness was analyzed by three-way analysis of variance (ANOVA) and teatite wear by two-way ANOVA and Tukey Honest Difference (HSD) (=.05).
RESULTS
There was no effect of Y-TZP brand on surface roughness (=.216) and steatite loss (=.064). A significant interaction effect (<.001) between surface condition and CS on Y-TZP roughness was observed. GZ specimens showed higher roughness after CS (before CS - 3.7 ± 1.8 µm; after CS - 13.54 ± 3.11 µm), with partial removal of the glaze layer. Indenters abraded against CPZ (0.09 ± 0.03 mm) were worn more than those abraded against PVZ (0.02 ± 0.01 mm) and GZ (0.02 ± 0.01 mm). Higher wear caused by direct abrasion against zirconia was confirmed by SEM.
CONCLUSION
Polishing with an intraoral polishing system did not reduce the roughness of zirconia. Wear of the opposing artificial enamel was affected by the material on the surface rather than the finishing technique applied, indicating that polished zirconia is more deleterious to artificial enamel than are glazed and porcelain-veneered restorations.
PubMed: 31297175
DOI: 10.4047/jap.2019.11.3.162 -
Australian Dental Journal Mar 2009Non-carious cervical lesions involve loss of hard tissue and, in some instances, restorative material at the cervical third of the crown and subjacent root surface,... (Review)
Review
Non-carious cervical lesions involve loss of hard tissue and, in some instances, restorative material at the cervical third of the crown and subjacent root surface, through processes unrelated to caries. These non-carious processes may include abrasion, corrosion and possibly abfraction, acting alone or in combination. Abfraction is thought to take place when excessive cyclic, non-axial tooth loading leads to cusp flexure and stress concentration in the vulnerable cervical region of teeth. Such stress is then believed to directly or indirectly contribute to the loss of cervical tooth substance. This article critically reviews the literature for and against the concept of abfraction. Although there is theoretical evidence in support of abfraction, predominantly from finite element analysis studies, caution is advised when interpreting results of these studies because of their limitations. In fact, there is only a small amount of experimental evidence for abfraction. Clinical studies have shown associations between abfraction lesions, bruxism and occlusal factors, such as premature contacts and wear facets, but these investigations do not confirm causal relationships. Importantly, abfraction lesions have not been reported in pre-contemporary populations. It is important that oral health professionals understand that abfraction is still a theoretical concept, as it is not backed up by appropriate clinical evidence. It is recommended that destructive, irreversible treatments aimed at treating so-called abfraction lesions, such as occlusal adjustment, be avoided.
Topics: Bite Force; Bruxism; Dental Occlusion, Traumatic; Dental Restoration, Permanent; Dental Stress Analysis; Finite Element Analysis; Humans; Occlusal Adjustment; Occlusal Splints; Terminology as Topic; Tooth Cervix; Tooth Diseases
PubMed: 19228125
DOI: 10.1111/j.1834-7819.2008.01080.x -
BMC Oral Health Oct 2014The purpose of this study was to use functional magnetic resonance imaging (fMRI) to quantify changes in brain activity during experimental occlusal interference. (Comparative Study)
Comparative Study
BACKGROUND
The purpose of this study was to use functional magnetic resonance imaging (fMRI) to quantify changes in brain activity during experimental occlusal interference.
METHODS
Fourteen healthy volunteers performed a rhythmical tapping occlusion task with experimental occlusal interference of the right molar tooth at 0 mm (no occlusion), 0.5 mm, and 0.75 mm. The blood-oxygen-level dependent (BOLD) signal was quantified using statistical parametric mapping and compared between rest periods and task periods.
RESULTS
In tapping tasks with experimental occlusal interference of 0.75 mm or 0.5 mm, there was clear activation of the contralateral teeth-related primary sensory cortex and Brodmann's area 46. At 0 and 30 minutes after removal of the experimental occlusal interference, the activation clearly appeared in the bilateral teeth-related primary sensory cortices and Brodmann's area 46. At 60 minutes after the removal of the experimental occlusal interference, the activation of Brodmann's area 46 had disappeared, and only the bilateral teeth-related primary sensory cortices were active.
CONCLUSIONS
The present results suggest that adjustments for experimental occlusal interference can be objectively evaluated using fMRI. We expect that this method of evaluating adjustments in occlusal interference, combined with fMRI and the tapping task, could be applied clinically in the future.
Topics: Adult; Brain; Cerebellum; Cerebral Cortex; Dental Occlusion, Traumatic; Female; Humans; Image Enhancement; Magnetic Resonance Imaging; Male; Middle Aged; Motor Cortex; Neural Pathways; Oxygen; Prefrontal Cortex; Somatosensory Cortex; Thalamus; Time Factors; Tooth; Touch Perception
PubMed: 25304016
DOI: 10.1186/1472-6831-14-124 -
Heliyon May 2022The periodontal ligaments are very important sensory organ for our daily life such as perception of food size or hardness, determination of jaw position, and adjustment...
The periodontal ligaments are very important sensory organ for our daily life such as perception of food size or hardness, determination of jaw position, and adjustment of masticatory strength. The sensory properties of the periodontal ligament, especially those of the maxillary and mandibular molars, have not yet been fully investigated. Somatosensory evoked magnetic fields (SEFs) can be measured and evaluated for latency and intensity to determine the sensory transmission characteristics of each body parts. However, previous reports on SEFs in the oral region have only reported differences in upper and lower gingival and lip sensations. In this study, the aim was to clarify these sensory characteristics by measuring SEFs during mechanical stimulation of the periodontal ligament in the maxillary and mandibular first molars. Somatosensory evoked magnetic fields were measured in the contralateral hemispheres of 33 healthy volunteers. Mechanical stimulation of the maxillary and mandibular right first molars, and the left wrist was performed with a specific handmade tool. The first peak latency for the mandibular first molars was 41.7 ± 5.70 ms (mean ± SD), significantly shorter than that for the maxillary first molars at 47.7 ± 7.36 ms. The peak intensity for the mandibular first molars was 13.9 ± 6.06 nAm, significantly larger than that for the maxillary first molars at 7.63 ± 3.55 nAm. The locations in the contralateral hemispheres showed no significant difference between the maxillary first molars and mandibular first molars. These locations were more anteroinferior and exterior than that of the wrist, as suggested by the brain homunculus. Neural signals from the mandibular periodontal ligaments pass faster and more intensely to the central nervous system than those from the maxillary periodontal ligaments, and may preferentially participate in adjustment of the occlusal force and the occlusal position.
PubMed: 35620631
DOI: 10.1016/j.heliyon.2022.e09464