Reliabilty of recording occlusal contacts by using intraoral scanner and articulating paper - A prospective study

OBJECTIVE

The recording of occlusal contacts is a pivotal step in many dental procedures, yet the lack of a standardized method could introduce clinical errors. The aim of this study was to compare the occlusal contacts recorded using a intraoral scanner to the contacts recorded using articulating paper. As a secondary outcome, the subjective clinical assessment made using the two methods was compared between different observers.

METHODS

Twenty-eight records were analysed for this study. Digital scan and intraoral photos of the coloured marks impressed by articulating paper were taken at the same time point for every patient. Using a standardized occlusal template, two operators recorded the number of occlusal contacts for every tooth provided by the two techniques. Then, 11 clinicians analysed the collected records and answered questions about the quality of the occlusions observed.

RESULTS

The statistical analysis showed significant differences between the number of contacts recorded by digital scan and those recorded by the photographed articulation marks, except in the case of the upper central incisors and first premolars. The Kappa Fleiss showed slight and fair agreement between clinicians when judging the occlusions.

CONCLUSION

The occlusal contacts recorded using the intraoral scanner and those recorded with the articulating paper did not match, and overall the clinicians showed low agreement when rating the recorded data.

CLINICAL SIGNIFICANCE

Despite of the great clinical importance of occlusal contact there is a lack of a precise method for recording and collecting occlusal contacts.

Distribution patterns of occlusal contact areas on natural posterior teeth - Evaluations of a cross-sectional population-based study with the Greifswald Digital Analyzing System (GEDAS)

AIM

The aim of our investigations is to optimize the anatomical basis for the design of a sufficient occlusal relationship, especially in view of the innovative technologies by analyzing the occlusal contact point patterns at cusp structures according to A-, B-, C- localization tooth by tooth on the individual occlusal surfaces in the posterior region in static habitual occlusal position.

MATERIALS AND METHODS

In 3300 subjects of the population-based Study of Health in Pomerania (SHIP 1) the interocclusal registration in habitual intercuspation using silicone registration was used and analyzed by using the special evaluation software Greifswald Digital Analyzing System (GEDAS II). Chi square test was used to investigate whether the distribution of contact areas differed in the group of premolars or molars - each considered separately for maxilla and mandible - on the basis of the probability of error p < 0.05.

RESULTS

In 709 subjects (446 male with a mean age of 48.9 ± 13.04 years; 283 female with a mean age of 52.4 ± 14.23 years) the antagonistic situation was specifically considered on natural posterior teeth without conservative or restorative-prosthetic interventions, i.e. without caries, fillings, crowns or other restorations. On the basis of these subjects, the silicone registrations were analyzed using GEDAS II. For the first and second upper molars, the ABC contact distribution was the most frequent: 20.4 % for the first and 15.3 % for the second molar. The second most frequent contact area for maxillary molars was area 0. The upper molars had contact areas only at the maxillary palatal cusp (B-/C-contacts). This contact relationship was most frequent in the maxillary premolar (18.1-18.6 %). In mandibular premolars, with the buccal cusps areas A and B were frequently involved (15.4-16.7 %). Mandibular molars showed a frequent contact pattern involving all A-, B-, C- and 0- contact areas (13.3-24.2 %). To capture the possible influence of the antagonistic dentition situation, the antagonistic situation was specifically considered and except for the mandibular premolars (p < 0.05) the contact distribution did not differ for molars and maxillary premolars regarding the dental status of the antagonistic teeth. Natural posterior teeth without occlusal contacts were observed from 20.0 % in the second lower molars to 9.7 % in the first upper molars.

CONCLUSION

Our results suggest a clinically relevant due to the fact, that this study is the first population-based epidemiological study to analyze the occlusal contact point patterns at cusp structures according to A-, B-, C- localization tooth by tooth on the individual occlusal surfaces in the posterior region in static habitual occlusal position in order to optimize the anatomical basis for the design of a sufficient occlusal relationship.

Clinical study comparing the accuracy of interocclusal records, digitally obtained by three different devices

OBJECTIVE

The aim of the present cross-sectional study was to compare the interocclusal contact records obtained by three different digital methods (intra- and extraoral digital scanners and T-Scan III system) with the conventional method (articulating paper).

MATERIALS AND METHODS

Twenty-five healthy volunteers were selected. As a control group, maximum intercuspation occlusal contacts were registered and photographed from the patients with an 8 µm articulating paper. Then, intraoral conventional elastomer impressions were taken and after obtaining the corresponding plaster models of every patient they were scanned with an extraoral scanner (Zfx Evolution, Zimmer Biomet Dental) (group 1). Moreover, digital impressions were made with an intraoral scanner (Trios Color POD, Phibo, 3Shape) and contacts were also registered (group 2). Finally, T-Scan III records were made and stored for further analysis (group 3). Two previously calibrated examiners independently evaluated the interocclusal contacts from every group. Data was analyzed by using Kappa index test and Pearson's chi-square test. Diagnostic tests and ROC curve were also performed.

RESULTS

Kappa interoperator index was 70.6% (better agreement). In Kappa intraoperator index, the best value was obtained in the intraoral scanner group (moderate agreement) and the worst with T-Scan III group (low agreement). ROC curve showed highest values in the intraoral scanner group (0.817) and lowest values in the T-Scan III group (0.613).

CONCLUSION

Results suggest greater reliability to record occlusal contacts with the intraoral scanner.

CLINICAL RELEVANCE

Intraoral scanners seem to be reliable in registering intermaxillary occlusal contacts when compared with the current gold standard.

Bite force changes after surgical correction of mandibular prognathism in subjects with increased vertical dimension : A prospective clinical trial

PURPOSE

Occlusal bite force (OBF) is the most important parameter in assessing biting efficiency. The aim of this study was to record OBF changes after surgical correction of high angle maxillary/mandibular (Max/Mand) class III patients and to compare these with that recorded in class III patients with average Max/Mand angle.

MATERIALS AND METHODS

Initially included were 42 patients with severe class III skeletal malocclusion who were scheduled for orthodontic surgery: group 1-22 patients with increased vertical relationship scheduled for bimaxillary surgery; group 2-20 patients with average vertical relationship scheduled for mandibular setback only. OBF measurements before surgery (T0), at debonding (T1) and at least 3 months after debonding (T2) were recorded using a portable occlusal force gauge. The following were also measured: maximum OBF (MOBF) achieved by the subject on each side, averaged OBF on each side (AOBF) and maximum OBF at the incisal region (MIOBF). At T2, only 33 patients (group 1: 17 and group 2: 16) were included in the analysis due to loss to follow-up.

RESULTS

MOBF increased significantly in group 1, while no significant changes were detected in group 2. MIOBF increased after surgical correction in both groups. Significant increase in MIOBF was observed at T1 (P < 0.001) followed by an insignificant decrease during the observation period (3-6 months after treatment; P > 0.05). The two groups differed significantly in MOBF at T1 and T2, while no statistically significant differences were detected between the groups for MIOBF changes at the various time intervals (P > 0.05). The number of posterior teeth with occlusal contacts increased in both groups. Relapse was detected in group 1 where the number of posterior teeth in contact decreased during the observation period (T1-T2).

CONCLUSION

OBF greatly improved after surgical correction of the vertical morphology. Correction of high angle mandibular prognathism improves oral function in addition to esthetics.

Maxillary expansion or contraction and occlusal contact adjustment: effectiveness of current aligner treatment

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.

[Design of points, lines and planes in the reconstruction of occlusion and the risk control in implantation]

Occlusion reconstruction involves various factors, such as joints, muscles, teeth and mental states. The relationship between implantation complications and occlusion, especially in the method of reducing the risk of implantation during occlusal reconstruction, is more and more emphasized by clinicians. This article mainly summarized the essentials of occlusal factors, such as mandibular position, cusp inclination and occlusal contacts, Spee's curve, Wilson curve and occlusal plane, in clinical treatment from the perspective of static geometry, dynamic functional movement in points, lines and planes, in order to accomplish precise occlusion reconstruction to achieve a stable and functional occlusion reconstruction, i.e. comfortable mandibular position, reasonable protrusive and lateral guidance, firm retrusive control and stable posterior supports, and to maintain the stability of implant.

Effects of a new type of clear overlay retainer on occlusal contacts

The popularity of clear overlay retainers (CORs) has increased recently because of their advantages such as better esthetics, cost effectiveness, easy fabrication, and good compliance. However, a deficiency in posterior occlusal settling is a reported limitation of CORs. The aim of this study was to evaluate the posterior occlusal contact changes in a new type of clear orthodontic retainer called Oral-treaper (OTP), which consists of three layers and has stronger mechanical characteristics than do conventional retainers. Three patients who completed fixed orthodontic treatment received OTP as a removable retainer. Cast models were fabricated after the removal of fixed appliances (T1) and after 4 to 11 months of using the retainers (T2). We evaluated all the cast models to compare the post-orthodontic settling pattern during the use of the OTPs. The depth of occlusal contacts was evaluated using color maps. The OTP did not prevent vertical settling in all patients but resulted in an improvement in posterior occlusal contact points.