Construction of virtual intercuspal occlusion: Considering tooth displacement

Quantitative evaluation of the proximal contact area gap change characterization under intercuspal occlusion by intraoral 3D scanning: Food impaction with tight proximal contact

OBJECTIVE

This study aimed to present three indicators that represent the proximal contact area gap change under intercuspal occlusion and to see if and how these indicators influence food impaction with tight proximal contact.

MATERIALS AND METHODS

Ninety volunteers were recruited for bite force measurement and intraoral scanning. Three-dimensional surface data and buccal bite data were obtained for 60 impacted and 60 non-impacted teeth. The scanning data were imported into the Geomagic Studio 2013 to measure three indicators, which included the gap change maximum (Δdm, μm), the buccolingual position of Δdm (P), and the gap expanded buccolingual range (S, mm). The difference between two groups of three indicators and their relationship with food impaction with tight proximal contact were analyzed by the t test, the Pearson chi-squared test, the nonparametric Mann-Whitney U test, and the binary logistic regression analysis (a = 0.05).

RESULTS

All indicators (Δdm, P, and S) were statistically different (p < 0.001, p = 0.002, and p < 0.001) in the impacted and non-impacted groups. Food impaction with tight proximal contact was affected by Δdm and S (p < 0.001, p = 0.039), but not by P (p = 0.409).

CONCLUSION

The excessive increase of the gap change maximum and the gap expanded buccolingual range under bite force promoted the occurrence of food impaction with tight proximal contact.

CLINICAL SIGNIFICANCE

The use of intraoral scanning to measure the characteristics of the proximal contact area gap change under bite force may help to deepen our understanding of the pathogenesis of food impaction with tight proximal contact. Importantly it can provide a reference basis for individualizing and quantifying occlusal adjustment treatment.

The impact of mandibular partial edentulous distal extension on virtual occlusal record accuracy when using two different intraoral scanners: An in vitro analysis

OBJECTIVES

This in vitro study was formulated to clarify how mandibular partial edentulous distal extension involving three missing teeth affects the virtual occlusal record (VOR) accuracy, in terms of both trueness and precision, when using two different intraoral scanners (IOSs) - the Primescan (PS) and Trios 4 (TR) scanners.

METHODS

A typodont model missing the left mandibular second premolar, first molar, and second molar as well as the right mandibular first molar was mounted on a semi-adjustable articulator. Four implants were placed at the sites of the missing mandibular teeth. Six pairs of stainless steel markers (diameter: 0.5 mm) were affixed to the maxillary and mandibular casts in the buccal gingiva adjacent to the implants and on the facial surfaces of teeth as reference positions for measurements. The model was digitized with an inEox X5 laboratory scanner to create a reference dataset. Intraoral scans were performed with the PS and TR scanners, with each scan duplicated 10 times to generate 20 paired IOS files. Automatic VOR generation followed the bilateral buccal scan protocol, divided into PS and TR groups (n = 10). Six subgroups of linear distances between interarch markers were assessed with Geomagic Control software, comparing deviations from the reference scan. Data normality was confirmed with the Shapiro-Wilk test. Trueness was evaluated with two-way ANOVAs and pairwise comparisons performed with Tukey's test, whereas precision was assessed with the Levene test (α=0.05).

RESULTS

The mean linear deviation (Δd) and standard deviation (SD) of VOR were both significantly affected by marker position (P < 0.001), and a significant position × scanner interaction was detected (P < 0.001). Negative mean deviations were observed for the distally extended edentulous areas in both groups. PS scans exhibited trueness that was significantly better than that for TR scans in the D16-46, D13-43, D23-33, and D27-37 subgroups (P < 0.05), whereas there were no significant differences in the D25-35 or D26-36 subgroups. PS scanning was associated with significantly better precision than TR scanning (P < 0.001), and worse precision was observed at D27-37 for both tested IOSs.

CONCLUSIONS

Mandibular partial edentulous distal extension can significantly affect VOR accuracy. The type of IOS could also affect VOR accuracy depending on the area being scanned, with better overall performance observed for the Primescan device as compared to the Trios 4 scanner. Both of these IOSs tended to underestimate VOR occlusal dimensions in mandibular distally extended edentulous areas.

CLINICAL SIGNIFICANCE

Mandibular distal edentulous areas can contribute to occlusal dimensions that are underestimated in digital workflows, which may result in infraocclusal discrepancies that arise when performing restorations. IOSs and VOR scanning protocols should thus be carefully considered in order to minimize these risks.

Does the available interocclusal space influence the accuracy of the maxillomandibular relationship captured with an intraoral scanner?

STATEMENT OF PROBLEM

The accuracy of a maxillomandibular relationship acquired by intraoral scanners (IOSs) has been previously analyzed; however, the impact of the interocclusal space on the accuracy of the maxillomandibular relationship remains unknown.

PURPOSE

The purpose of this in vitro investigation was to evaluate the influence of the interocclusal space (0, 1, 2, 3, or 4 degrees of incisal opening in the articulator) on the accuracy of the maxillomandibular relationship captured with an IOS.

MATERIAL AND METHODS

Markers were attached to the first molars and canines of maxillary and mandibular diagnostic casts, which were mounted on a semi-adjustable articulator, and digital scans were acquired (TRIOS 4). Both digital scans were duplicated 100 times and distributed into 5 groups depending on the incisal pin opening in the articulator (n=20): 0 (Group 0), 1 (Group 1), 2 (Group 2), 3 (Group 3), and 4 degrees (Group 4). In Group 0 (control), the casts were maintained in maximum intercuspation (MIP) with the incisal pin of the articulator set at 0 degrees. Then, a bilateral virtual occlusal record was acquired and automatically processed by using the IOS software program. A laboratory scanner (Medit T500) was used to digitize the mounted casts. The same procedures were completed in Groups 1, 2, 3, and 4 but with the incisal pin set at 1, 2, 3, and 4 degrees respectively. The interlandmark distances were used to calculate the discrepancies between the control and groups tested. One-way analysis of variance (ANOVA) and pairwise comparison Tukey HSD tests were used to inspect the data (α=.05).

RESULTS

The interocclusal space available when capturing the occlusal records affected the trueness of the maxillomandibular virtual relationship measured (P<.001). Group 0 (135 μm) obtained the highest distortion, while Group 3 (73 μm) and Group 4 (71 μm) showed the lowest distortion. Additionally, the interocclusal space available (P<.001) impacted the precision of the maxillomandibular virtual relationship measured. Group 0 (111 μm) obtained the highest distortion, while Group 4 (precision mean value of 59 μm) had the lowest distortion among the groups tested.

CONCLUSIONS

The interocclusal space available when acquiring virtual bilateral occlusal records using the IOS tested impacted the accuracy of the maxillomandibular relationship. The smallest available interocclusal space tested (maximum intercuspation) showed the worst trueness and precision mean values, while the group with the largest interocclusal space available had the highest trueness and precision mean values among the groups studied.

Recording maximal intercuspation and border positions of the mandible with intraoral scanner using the acquisition software's multi-occlusion function

PURPOSE

This in vitro study was conducted to investigate the accuracy of intraoral scanner (IOS) for recording maximal intercuspal position (MIP) and border positions of the mandible.

MATERIALS AND METHODS

Maxillary and mandibular master casts were articulated in MIP, protrusive, and lateral interocclusal position sequentially on a semi-adjustable articulator. For each articulation relation, sites of occlusal contacts (SOCs) and sites of clearance (SCs) were identified on the master casts with articulating paper (reference sites). IOS was used to take full arch scans and nine virtual interocclusal records (VIRs) for virtual articulation of models. Virtual SOCs and SCs were detected with 3D processing software and compared to those identified with the articulating paper. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each articulation relation.

RESULTS

For MIP, IOS showed adequate sensitivity and NPV of 100%, and specificity and a PPV of 99%. For protrusive position, the IOS showed a sensitivity and a NPV of 100%, a high PPV of 86%, and a specificity of 83%. For lateral positions, the specificity and the PPV were high (93% and 79%, respectively), but the sensitivity and the NPV were below the clinically acceptable limits (28% and 56%, respectively).

CONCLUSION

IOS displayed clinically acceptable accuracy for recording MIP and protrusive border mandibular position. However, IOS had less accuracy for lateral border mandibular position.

A digital technique for occlusal design of a posterior full crown based on physiological tooth displacement and occlusion of adjacent teeth

This article presents a digital technique to construct a virtual occlusion in the maximal intercuspal position (MIP), considering physiological tooth displacement and reducing intermesh penetrations between occlusal surfaces, in order to design more precise and accurate occlusal contacts of a posterior full crown.

Accuracy of digital and conventional systems in locating occlusal contacts: A clinical study

STATEMENT OF PROBLEM

The accuracy of methods used for locating occlusal contacts throughout the entire clinical procedure has been poorly studied.

PURPOSE

The purpose of this clinical study was to determine the reproducibility and criterion validity for different methods of locating occlusal contacts.

MATERIAL AND METHODS

Thirty-two adults with natural dentitions participated in this cross-sectional test-retest study. In total, occlusal contacts at maximum intercuspation were recorded by using 15 methods: silicone transillumination with Occlufast Rock (40, 50, 100, and 200 µm) and Occlufast CAD (40 and 50 µm); virtual occlusion (100, 200, 300, and 400 µm); articulating film (12-, 40-, 100-, and 200-µm-thick); and T-Scan III. Images of the occlusal records were scaled and calibrated spatially, and the occlusal contacts of the right posterior mandibular teeth were delimited by using the FIJI software program. Reproducibility was expressed as 95% confidence intervals (95% CI) of the percentage of agreement in the location of the occlusal contacts between images from the test sessions against retest sessions using the same method. Criterion validity was expressed as 95% CI of the percentage of agreement in the location of the occlusal contacts between images from the test sessions against images from Occlufast Rock (criterion standard).

RESULTS

Occlufast Rock achieved 85% to 95% agreement in the location of the occlusal contacts between the 2 sessions, whereas Occlufast CAD, 200-µm articulating film, and T-Scan offered 79% to 86%, 68% to 75%, and 65% to 75% agreement, respectively. The most valid method was Occlufast CAD (74% to 80%) followed by the 200-µm articulating film (57% to 63%), 400-µm virtual occlusion (53% to 62%), 100-µm articulating film (52% to 60%), and T-Scan (48% to 56%).

CONCLUSIONS

Conventional methods, such as 100- and 200-µm articulating film and digital methods, including 400 µm virtual occlusion and T-Scan, offer sufficient accuracy in locating the occlusal contacts. However, strategies are needed to improve accuracy.

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.

Digital superimposition of scans for recording and transferring vertical relation from provisional restorations when rehabilitating worn-out dentition: A dental technique

Excessive wear of the natural dentition results in the loss of tooth anatomy and the vertical dimension of occlusion (VDO) which may necessitate full mouth rehabilitation. Successful full-mouth rehabilitation with increased VDO requires accurate recording and transfer of the newly raised VDO with provisional restorations. Conventional bite registration can incur errors during the recording and transfer of vertical dimensions. This article introduces a digital approach-the superimposition of scans using an intraoral scanner (IOS) to transfer VDO, occlusion, and aesthetic data from provisional restorations for designing and fabricating indirect restorations in the management of worn-out dentition.

Virtual occlusal records acquired by using intraoral scanners: A review of factors that influence maxillo-mandibular relationship accuracy

PURPOSE

This review aims to provide a comprehensive summary of how much progress has been made in the field of virtual occlusal records (VOR) obtained with intraoral scanners (IOSs), their accuracy, and what factors influence their accuracy.

MATERIALS AND METHODS

An electronic search was performed in MEDLINE via PubMed and Scopus databases in February 2023. Eligible articles were clinical or in vitro studies evaluating the accuracy of virtual occlusal records with intraoral scanners in completely dentate and partially edentulous arches.

RESULTS

Virtual occlusal records have shown promising results in terms of accuracy, with some studies reporting a high level of agreement with traditional methods. Key factors influencing the accuracy of VOR through intraoral scanners were identified which encompass multiple parameters such as scanner brands, imaging technology, scan quality, best-fit alignment, software algorithms, intermesh penetrations, and the number of sections and dimensions of the virtual occlusal record. In partially edentate areas, the lack of landmarks in the edentulous area compromises the accuracy of VOR, thus limiting the use of IOS in patients with missing teeth.

CONCLUSION

Understanding and recognizing these influencing factors will increase the predictability and reliability of dental treatments completed by using digital workflows.  However, certain challenges need to be addressed which can influence its accuracy and limit its use in daily practice. Future research should focus on improving these factors to enhance the clinical applicability of virtual occlusal records.

Factors that influence the accuracy of maxillomandibular relationship at maximum intercuspation acquired by using intraoral scanners: A systematic review

OBJECTIVE

To review the factors that influence the accuracy of the maxillomandibular relationship at maximum intercuspation (MIP) acquired by using intraoral scanners (IOSs).

MATERIAL AND METHODS

A systematic search was performed using five databases: MEDLINE/PubMed, Cochrane, Embase, World of Science, and Scopus. A manual search was also completed. Studies assessing the factors that influence the MIP acquired by using IOSs were included and organized based on the analyzed factor. Studies were evaluated by applying the Joanna Briggs Institute Critical Appraisal Checklist.

RESULTS

Twenty-nine articles were included. Seven factors have been identified: IOS system, scan extension, edentulous areas, number, location, and extension of occlusal records, occlusal force, tooth mobility, and alignment methods. Nine studies evaluated the influence of IOS system. Four studies assessed the influence of the extension of the arch scan. Three studies evaluated the effect of edentulous spaces. Four studies agreed on the impact of the number, location, and extension of the occlusal records on the MIP accuracy. One study assessed the influence of the occlusal force, showing a smaller average interocclusal space with increased occlusal force. One study evaluated the influence of tooth mobility. Seven studies analyzed the influence of the alignment method on the MIP accuracy.

CONCLUSIONS

Most of the studies reported no difference on the MIP accuracy between half- and complete-arch scans. Areas with 2 or more missing teeth reduce the MIP accuracy. A bilateral and frontal record including 2 teeth or a bilateral posterior occlusal including at least 4-teeth is indicated for maximizing the MIP accuracy.

CLINICAL IMPLICATIONS

When a complete-arch intraoral scans is obtained, a bilateral and frontal record including 2 teeth or a bilateral posterior occlusal record including at least 4-teeth is recommended for maximizing the accuracy of the MIP. When a half-arch intraoral scan is acquired, a posterior occlusal record including at least 4-teeth is indicated for optimizing the accuracy of the MIP.

Clinical evaluation and quantitative occlusal change analysis of posterior implant-supported all-ceramic crowns: A 3-year randomized controlled clinical trial

OBJECTIVES

To compare the survival and complication rates of posterior screw-retained monolithic lithium disilicate (LS2 )/veneered zirconia (ZrO2 ) single implant crowns (SICs), as well as analyze the occlusal changes observed during a 3-year follow-up period.

MATERIALS AND METHODS

Thirty-three patients were included and randomly divided into two groups. The test group consisted of 17 patients who received monolithic-LS2 -SIC, while the control group consisted of 16 patients who received veneered-ZrO2 -SIC. Implant/prosthesis survival rates, technical complications, peri-implant soft tissue conditions, and quantitative occlusal changes of SIC (obtained by the intra-oral scanner and analyzed in reverse software Geomagic Control 2015) were assessed at 1- and 3-year follow-ups. Bone loss and Functional Implant Prosthodontic Score (FIPS) were evaluated at a 3-year follow-up.

RESULTS

After a 3-year follow-up period, one patient dropped out of the follow-up. No implant loss was observed. One crown was fractured, resulting in prosthesis survival rates of 93.75% for the monolithic group and 100% for the veneered group. A technical complication rate of 25% (4/16) was observed in the veneered group (p = .333). No significant differences in the marginal bone loss were observed at the 3-year follow-up (0.00 (-0.22, 0.17) mm versus 0.00 (-0.12, 0.12) mm, p = .956). The total FIPS scores for the test group were 9.0 (9.0, 9.0), while the control group received scores of 9.0 (8.0, 10.0) (p = .953). The changes in mean occlusal clearance were 0.022 ± 0.083 mm for the test and 0.034 ± 0.077 mm for the control group (at 3 years, p = .497). The changes in occlusal contact area were 1.075 ± 2.575 mm2 for the test and 1.676 ± 2.551 mm2 for the control group (at 3 years, p = .873).

CONCLUSION

After a 3-year follow-up, screw-retained monolithic LS2 and veneered ZrO2 SIC demonstrated similar survival rates. The occlusal performance of implant prostheses needs to be closely examined during follow-up, and appropriate occlusal adjustments need to be considered.

Digitally designed occlusion of an implant-supported crown considering physiological tooth displacement under occlusal loading

Physiological natural tooth displacement under occlusal loading can influence intraoral occlusal contacts. However, gypsum casts and digital scans cannot simulate the physiological tooth displacement under occlusal loading. The occlusal design of the implant-supported crowns has been based mainly on the experience of dental laboratory technicians, lacking accuracy and individualization. Therefore, a digital technique that considers physiological tooth displacement is presented to design the occlusion of implant-supported single crowns.

Clear Aligner Therapy: Up to date review article

The advantages of Clear Aligners Therapy (CAT) include the braces being virtually invisible, comfortable to wear, and removable for eating and brushing; that way, CAT can be used to treat a wide range of orthodontic issues. In 1999, the company Align Technology introduced the frst commercial clear aligner system called Invisalign. The Invisalign system was initially only available to orthodontists, but later became available to general dentists as well. The system quickly gained popularity among patients who were looking for a more discreet and comfortable alternative to traditional braces. In 2000, Align Technology received FDA clearance for the Invisalign system, which further increased its popularity. The biomechanics of clear aligners involve the use of custom-made tooth aligners that are specifcally shaped to guide teeth into desired positions. These aligners are typically made from flexible materials such as polyurethane or ethylene vinyl acetate and are adjusted to apply the necessary forces for tooth movement. Attachment devices, such as power ridges or buttons, are often used to enhance or assist in specifc tooth movements and for retention of the aligner. The use of attachments allows for the exertion of desired force on the teeth, which is crucial for the success of Clear Aligner Therapy. CAT should be used if patients are concerned about the esthetic appearances of their teeth-for example, actors and other individuals that rely on their appearances in public in a professional context-and if the misalignment is not severe, so that clear aligners can still work. One should not use CAT in cases of severe crowding or spacing issues that require extractions. If the patient has complex jaw discrepancies or skeletal issues or if teeth need to be moved extensively in multiple directions, CAT is likely not going to be strong enough. In conclusion, Clear Aligner Therapy is a safe, effective, and convenient orthodontic treatment option that offers patients a virtually invisible way to achieve a straighter, more beautiful smile. With continued advancements in technology and a growing body of research supporting its effectiveness, the future of Clear Aligner Therapy looks bright.

Assessment of physiological posterior-tooth displacement under habitual occlusal force by intraoral scanning using implant-supported crowns as the reference

STATEMENT OF PROBLEM

Studies that have used digital methods to quantitatively evaluate physiological tooth displacement under occlusal force are sparse.

PURPOSE

The purpose of this clinical study was to measure physiological posterior tooth displacement under occlusal force by intraoral scanning and reverse engineering technology by using implants as the reference.

MATERIAL AND METHODS

A total of 14 participants received 15 implant-supported single mandibular first molar crowns. The surface data of maxillary and mandibular posterior teeth (U1 and L1) and the buccal occlusal data in the maximum intercuspal position (MIP) with habitual occlusal force were obtained by using an intraoral scanner (TRIOS 3, v20.1.2). The U1 and L1 data were segmented into single teeth, which were then aligned to the buccal occlusal data by using the "best-fit alignment" command to build the data under occlusal force (U2 and L2). U1 and L1 data were compared with U2 and L2 data to calculate the centroid and functional cusp vertex displacements and the long axis deflections of the second premolars and second molars, taking the first molar as the reference. The medians, and first quartile (Q₁), third quartile (Q₃) of the above data were reported, and the Shapiro-Wilk and Wilcoxon tests were used to analyze the differences (α=.05).

RESULTS

Under occlusal force, the median (Q₁, Q₃) centroid displacements of posterior teeth ranged from 61 (52, 101) μm to 146 (80, 186) μm; the functional cusp vertex displacements ranged from 82 (62, 117) μm to 146 (98, 189) μm, and the long axis deflections ranged from 0.45 (0.25, 0.87) degrees to 1.03 (0.52, 1.41) degrees. Mandibular second premolars displaced lingually, mesially, and apically; mandibular second molars displaced distally and apically; and maxillary second premolars and second molars displaced lingually and apically.

CONCLUSIONS

A digital method taking implant-supported single crowns as the reference was used to demonstrate physiological posterior-tooth displacement under habitual occlusal force.

Effect of a novel interocclusal recording method on occlusal accuracy of implant-supported fixed prostheses: A randomized clinical trial

OBJECTIVES

To investigate the effect of a novel interocclusal recording method on the occlusal accuracy of implant-supported fixed prostheses for partially dentate patients with distal extension.

MATERIALS AND METHODS

Twenty patients with two or more adjacent teeth missing in the distal extension and scheduled to receive implant-supported fixed prostheses were enrolled. Two interocclusal recording methods were used: placing polyvinyl siloxane (PVS) on the interocclusal recording caps (test), and placing PVS on healing abutments (control). The intraoral occlusal contacts in maximal intercuspal position (MIP) were compared with those in the mounted casts to calculate sensitivity and positive predictive value (PPV). Then, patients were randomly allocated into two groups to determine which interocclusal record would be used. The implant prostheses' evaluations mainly included occlusal adjustment height, volume, and time, occlusal contact score based on articulating paper examination. Paired-samples t-test, Mann-Whitney U test, and least squares regression analyzed the statistic differences.

RESULTS

The test method had higher sensitivity to detect intraoral occlusal contacts than the control method (p = .002), but similar PPV (p = .10). During the prostheses' evaluations, the occlusal adjustment height in the test group was significantly lower than that in the control group [99.4 (53.2, 134.2) vs. 159.0 (82.3, 247.8) μm, p = .03], while the occlusal contact score before adjustment was higher (p = .006). The groups had similar occlusal adjustment volume and time.

CONCLUSIONS

The novel interocclusal recording method for implant-supported fixed prostheses was more accurate and could reduce the occlusal adjustment.

In vivo evaluation of the reliability and validity of three digital occlusion analysis methods

OBJECTIVES

The reliability and validity of three digital occlusion analysis methods was evaluated in vivo.

METHODS

The three method evalueated were:scanning of articulating paper marks (SA), dental prescale occlusal analysis system (DP) and a virtual occlusion constructed method (VO). A conventional silicone transmission method (ST) was used as the standard for comparison. Each of the 20 enroled human subjects was tested with the four methods. Retest of each method was performed at 2-week intervals. Occlusal contact area (OCA) and occlusal contact numbers (OCN) were calculated for analyses. For reliability evaluation, intraclass correlation coefficients (ICC) of the OCA and OCN values obtained from each method were compared. For validity evaluation, Pearson correlations coefficients, paired t-tests, regression analysis and Bland-Altman analysis were examined.

RESULTS

The ICC values of OCA and OCN were in the order: ST>SA>DP>VO. The highest OCA and OCN values were found ST while the lowest values were obtained from DP. Paired t-test identified a significant difference when OCA values obtained from the three digital methods were compared with ST, and between the OCN values of DP and ST. Pearson correlation showed high coefficients between ST and three digital methods (0.583-0.885 for OCA; 0.779-0.836 for OCN). A significant linear correlation was found between the results from ST and those from SA or VO. Bland-Altman analysis showed good agreement between OCN values of SA and ST, and between those of VO and ST.

CONCLUSIONS

The three digital occlusal analysis methods showed good reliability and validity for in vivo clinical application.

CLINICAL SIGNIFICANCE

The three digital occlusion analysis systems examined demonstrate good potential in in vivo quantitative analysis, with good reliability and validity. The use of these analytical methods should facilitate digital workflow in clinical practice.

Accuracy and precision of intraoral scanners for shade matching: A systematic review

STATEMENT OF PROBLEM

The use of intraoral scanners is rising in prosthetic dentistry; however, systematic analysis of their accuracy and precision for shade matching is scarce.

PURPOSE

The purpose of this systematic review was to evaluate the accuracy and precision of intraoral scanners for shade matching.

MATERIAL AND METHODS

In addition to a manual search, an electronic systematic search was conducted on MEDLINE/PubMed, EMBASE, Web of Science, Cochrane, and Scopus databases. English-language original studies published between January 1, 2010 and March 1, 2022 with intraoral or digital scanners were chosen based on the keywords of tooth color or shade selection or determination, color or shade matching, accuracy, validity, or trueness, and precision, repeatability, or reproducibility as inclusive criteria. Two reviewers independently performed the literature search, selected the studies, collected the data from the studies included, and evaluated the quality of the studies included using a quality assessment method and the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies. A third reviewer resolved disagreements.

RESULTS

A total of 17 articles concerning the shade matching accuracy and precision of intraoral scanners were selected and reviewed. Among them, 4 articles evaluated only accuracy, 4 articles assessed only precision, and 9 articles investigated both accuracy and precision. Ten articles reported low levels of shade matching accuracy for intraoral scanners, while 11 articles reported high levels of shade matching precision for intraoral scanners.

CONCLUSIONS

Based on the current literature, intraoral scanners show acceptable precision but unacceptable accuracy for shade matching.

Accuracy of intraoral scanners for static virtual articulation: A systematic review and meta-analysis of multiple outcomes

STATEMENT OF PROBLEM

Static virtual articulation with intraoral scanners (IOSs) can eliminate the human errors related to conventional articulation methods and enhance accuracy. A systematic review and meta-analysis based on multiple accuracy outcomes can combine the available literature and provide an evidence-based conclusion.

PURPOSE

The purpose of this systematic review and meta-analysis was to investigate whether static virtual articulation with IOSs has acceptable accuracy for completely dentate and partially edentulous patients.

MATERIAL AND METHODS

An electronic search was conducted on the PubMed, Web of Science, and Scopus databases. In addition, a manual search through reference lists of selected articles was performed. Clinical and in vitro studies evaluating the accuracy of static virtual articulation with IOSs based on diagnostic accuracy, trueness, precision, and occlusion of fabricated fixed restorations were included. The pooled results included sensitivity, specificity, positive likelihood ratio (+LR), negative likelihood ratio (-LR), diagnostic odds ratios (DORs), mean values, and 95% confidence intervals (CIs). Results were presented as forest plots. The summary receiver operator characteristic (SROC) was displayed to summarize the diagnostic test performance.

RESULTS

The initial search resulted in a total of 5061 articles, of which 29 articles were included in the analysis. The virtual interocclusal records (VIRs) with IOSs showed acceptable pooled results for diagnostic accuracy (sensitivity: 0.76; specificity: 0.80; DOR: 14.77, area under the SROC (AUC): 0.87; cut off point Q∗: 80; +LR: 3.66; -LR: 0.31). The pooled data for trueness and precision were within the acceptable limits. The pooled mean (95% CI) for trueness based on linear deviations was 243.53 (144.90, 342.17). The pooled mean (95% CI) for precision based on 3D deviation of articulated models was 54.97 (43.49, 66.46). In addition, the included studies reported accurate occlusion for fixed restorations fabricated by using VIRs with IOSs. Moreover, most of the studies on trueness based on virtual occlusal contact area reported acceptable accuracy.

CONCLUSIONS

VIRs with IOSs had acceptable accuracy for static virtual articulation.

Morphological design of occlusal wear facets for the mandibular first molar crown using different bite registration methods

PURPOSE

To compare the accuracy of occlusal wear facet morphology designed using different bite registration methods for mandibular first molar crowns.

MATERIALS AND METHODS

The posterior teeth and intraoral intercuspal occlusions of 12 participants were scanned. The abutment shape of the mandibular first molars for complete crowns was virtually designed, and the anatomic coping design method was used to design crowns. In the anatomic coping design, digital wax patterns were constructed by elevating the wear facets on the original surface of first molars and then adjusting the facets with 2 types of virtual occlusions determined by buccal bite registration (BBR) or segmented tooth registration (STR) methods, where the displacement of teeth under bite force was considered (STR) or not (BBR). The occlusal distance between the original wear facets and the antagonists as well as 3D deviations between the facets on the designed crowns and on the surfaces of the original teeth were measured. Paired-samples t-test was used to analyze the results (α = .05).

RESULTS

Regarding occlusal distance, the mean 3D deviation and the root mean square (RMS) values of BBR were greater than those of the STR groups (P<.001 and P = .008). The mean 3D deviations of the crowns of the BBR and STR groups were 0.19 ±0.04 mm and 0.14 ±0.06 mm, respectively and the RMS values were 0.22 ±0.03 mm and 0.18 ±0.04 mm (P<.001), respectively.

CONCLUSIONS

The morphology of occlusal wear facets of mandibular first molar crowns designed with the occlusion constructed using the segmented tooth registration method are more coincident with the original morphology. This article is protected by copyright. All rights reserved.

Artificial intelligence-designed single molar dental prostheses: A protocol of prospective experimental study

BACKGROUND

Dental prostheses, which aim to replace missing teeth and to restore patients' appearance and oral functions, should be biomimetic and thus adopt the occlusal morphology and three-dimensional (3D) position of healthy natural teeth. Since the teeth of an individual subject are controlled by the same set of genes (genotype) and are exposed to mostly identical oral environment (phenotype), the occlusal morphology and 3D position of teeth of an individual patient are inter-related. It is hypothesized that artificial intelligence (AI) can automate the design of single-tooth dental prostheses after learning the features of the remaining dentition.

MATERIALS AND METHODS

This article describes the protocol of a prospective experimental study, which aims to train and to validate the AI system for design of single molar dental prostheses. Maxillary and mandibular dentate teeth models will be collected and digitized from at least 250 volunteers. The (original) digitized maxillary teeth models will be duplicated and processed by removal of right maxillary first molars (FDI tooth 16). Teeth models will be randomly divided into training and validation sets. At least 200 training sets of the original and the processed digitalized teeth models will be input into 3D Generative Adversarial Network (GAN) for training. Among the validation sets, tooth 16 will be generated by AI on 50 processed models and the morphology and 3D position of AI-generated tooth will be compared to that of the natural tooth in the original maxillary teeth model. The use of different GAN algorithms and the need of antagonist mandibular teeth model will be investigated. Results will be reported following the CONSORT-AI.