Interocclusal Registration Research Articles

Dimensional stability and surface hardness of inter-occlusal recording materials

It is important to choose the appropriate interocclusal registration material for precise articulation and successful dental prosthesis fabrication. 3 types of interocclusal registration materials: Bite registration wax, polyvinyl siloxane bite registration paste and Bisacryl-based bite registration paste were evaluated for dimensional stability and surface hardness at 4 different time intervals. One way ANOVA test, multiple Post Hoc Tukey HSD test and nonparametric test were performed. Bisacryl-based bite registration material exhibited better dimensional stability and surface hardness than polyvinyl siloxane and bite registration wax at all 4 time intervals. Thus dimensional stability and surface hardness of interocclusal registration material was influenced by both the type of material and the time duration.

Verifying the seating of a 3D-printed removable die using elastomeric matrices: A dental technique.

Computer-aided design and computer-aided manufacturing systems enable digital designing and 3-dimensional (3D) printing of definitive casts with removable dies. However, the fit of the removable dies should be without interferences for their accurate positioning in the cast. Given that the accuracy of additive manufacturing depends on design- and manufacturing-related factors, verifying the accuracy of the position of 3D-printed removable dies in their cast is essential to fabricate positionally accurate definitive prostheses, which would enable minimal or no laboratory and clinical adjustments. This dental technique article presents a straightforward approach to verify the seating of a 3D-printed removable die by using verification matrices made of a polyvinylsiloxane interocclusal registration material.

Evaluation of the accuracy of a fully digital method of measuring sagittal condylar inclination.

This clinical study aimed to evaluate the accuracy of a fully digital technique for measuring sagittal condylar inclination (SCI), as well as validating whether differences existed between the left and right SCI values of the same participant, to provide a reference for clinical practice. Ten participants with good occlusal relationship and normal temporomandibular joint were recruited. Three methods were used to measure the SCI values of the participants, namely, A (mechanical facebow transferring and mechanical articulator-based measuring method with physical protrusive interocclusal registration), B (face scan-based virtual facebow and virtual articulator-based measuring method with digital protrusive interocclusal registration), and C (jaw motion tracking system-based measuring method). With the group subjected to methods A and C as the control, the SCI values obtained by the three methods were statistically analyzed. The left and right SCI values of the same participant were also compared. The left and right SCI values measured by method A were 41.70°±7.09° and 42.80°±8.62°, those by method B were 35.09°±12.49° and 37.63°±12.10°, and those by method C were 39.43°±8.72° and 38.45°±6.91°. No significant difference existed among the SCI values measured by the three methods (P>0.05). Meanwhile, no statistical difference existed between the SCI values on the left and right sides of the same participant (P>0.05). The accuracy of the virtual facebow and digital protrusive occlusal registration based SCI measuring method was the same as that of mechanical facebow based and jaw motion tracking system-based methods. The SCI values on the left and right sides of the same participant were similar. Clinically, an appropriate SCI measurement and setting strategy can be selected based on the actual situations.

USE OF LITHIUM DISILICATE VENEERS AND CROWNS IN ELDERLY PATIENTS:CASE REPORT

Introduction: Dental planning is fundamental in complex rehabilitations, restoring function and aesthetics through fixed metal-free restorations. Objectives: The objective of this study was to report an aesthetic and functional biological approach to a complex clinical case, restoring function and aesthetics, reestablishing the vertical dimension of occlusion by replacing tooth loss and an integrative review of the literature. Case report: Patient GEF, 70 years old, male, was admitted to the Dental Prosthesis clinic - Funorte, and his main complaint was “my teeth are small and worn out”. After undergoing clinical evaluation and carrying out complementary imaging exams (panoramic radiography), the following plan was proposed: upper wax-up; lower removable partial denture (RPD) – increase and restoration of the vertical dimension of occlusion (DVO); single crowns made on dental elements 14, 15, 21, 22, 23, 24 and 25 and Fixed Partial Prosthesis with 3 elements on teeth (11 to 13) Installation of fiberglass posts on elements 13 and 14; Filling and preparation core for full crown and inter-occlusal registration, impression with dense addition silicone followed by fluid addition silicone, wax try-in and cementation. Conclusion: Dental planning is essential to achieve favorable results, increasing OVD can be carried out successfully, as long as there is correct diagnosis and planning, the use of metal free prostheses have excellent aesthetic properties, which allows achieving a more natural result .

A novel method for testing accuracy of bite registration using intraoral scanners.

The evidence on the accuracy of bite registration using intraoral scanners is sparse. This study aimed to develop a new method for evaluating bite registration accuracy using intraoral scanners. Two different types of models were used; 10 stone models and 10 with acrylic resin teeth. A triangular frame with cylindrical posts at each apex (one anterior and two posteriors) was digitally designed and manufactured using three-dimensional (3D) printing. Such a structure was fitted in the lingual space of each maxillary and mandibular model so that, in occlusion, the posts would contact their opposing counterparts, enforcing a small interocclusal gap between the two arches. This ensured no tooth interference and full contact between opposing posts. Bite registration accuracy was evaluated by measuring the distance between opposing posts, with small values indicating high-accuracy. Three intraoral scanners were used: Medit i500, Primescan, and Trios 4. Viewbox software was used to measure the distance between opposing posts and compute roll and pitch. The average maximum error in interocclusal registration exceeded 50 μm. Roll and pitch orientation errors ranged above 0.1 degrees, implying an additional interocclusal error of around 40 μm or more. The models with acrylic teeth exhibited higher errors. A method that avoids the need for reference hardware and the imprecision of locating reference points on tooth surfaces, and offers simplicity in the assessment of bite registration with an intraoral scanner, was developed. These results suggest that intraoral scanners may exhibit clinically significant errors in reproducing the interocclusal relationships.

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)

AimThe 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 methodsIn 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. ResultsIn 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. ConclusionOur 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.

Comparison accuracy of digital and analog method using milled occlusal splints.

This clinical trial aims to compare the accuracy of interocclusal registration in centric relation taken with polyvinyl siloxane and intraoral scanner (IOS) with the fabrication of occlusal devices. Thirty-one participants were included in the trial registered at ClinicalTrials.gov (NCT05317182) receiving two different occlusal devices from two different workflows. One workflow was performed using polyvinyl siloxane impression material and the other with IOS. Every splint was scanned before and after the occlusal adjustments to compare the volumetric changes using the Root Mean Square deviation (RMS). Furthermore, three evaluators assessed the 3D comparison using color maps in a Visual Analog Scale (VAS). The average values of RMS were higher for the analog approach (0.01 ± 0.067) than the digital approach (0.065 ± 0.035). However, the differences were not statistically significant (p < 0.063) between the two impression techniques. For the semiquantitative analysis performed by blinded evaluators, differences in VAS values between the impression for the digital (2.08 ± 2.4) and analog (3.80 ± 3.3) technique were statistically significant. The three evaluators agreed in more than 90% of the qualitative dichotomous evaluation. Digital impressions did not show inferior accuracy compared to conventional impressions when assessed using quantitative measurements. This clinical trial provided evidence on registering interocclusal relationship at increased vertical dimension with fully digital workflow for complete arch prosthesis.

Accuracy comparison of bilateral versus complete arch interocclusal registration scans for virtual articulation

Statement of problemAlternatives to the bilateral interocclusal registration scanning technique to improve virtual articulation have not been fully investigated. PurposeThe purpose of this in vitro study was to compare the accuracy of virtually articulating digital casts by using bilateral interocclusal registration scans versus a complete arch interocclusal scan. Material and methodsA set of maxillary and mandibular reference casts were hand-articulated and mounted on an articulator. The mounted reference casts were scanned, and the maxillomandibular relationship record was scanned 15 times using 2 different scanning techniques, the bilateral interocclusal registration scan (BIRS) and complete arch interocclusal registration scan (CIRS), with an intraoral scanner. The generated files were transferred to a virtual articulator, and each set of scanned casts was articulated using BIRS and CIRS. The virtually articulated casts were saved as a set and transferred to a 3-dimensional (3D) analysis program. The scanned casts were set in the same coordinate system as the reference cast and overlaid on top of the reference cast for analysis. Two anterior and 2 posterior points were selected to determine points of comparison between the reference cast and test casts virtually articulated with BIRS and CIRS. The mean discrepancy between the 2 test groups and the anterior and posterior mean discrepancy within each group were tested for significance by using the Mann-Whitney U test (α=.05). ResultsA significant difference was found between the virtual articulation accuracy of BIRS and CIRS (P<.001). The mean deviation for BIRS was 0.053 ±0.051 mm and that for CIRS was 0.265 ±0.241 mm. Furthermore, significant differences were found between the anterior and posterior deviations in both BIRS (P=.020) and CIRS (P<.001). The mean deviation for BIRS was 0.034 ±0.026 mm in the anterior and 0.073 ±0.062 mm in the posterior. The mean deviation for CIRS was 0.146 ±0.108 mm anteriorly and 0.385 ±0.277 mm posteriorly. ConclusionsBIRS was more accurate than CIRS for virtual articulation. Moreover, the alignment accuracy of anterior and posterior sites for both BIRS and CIRS exhibited significant differences, with the anterior alignment exhibiting better accuracy in relation to the reference cast.

Accuracy of optical interocclusal registration using an intraoral scanner.

This study aimed to clarify the effect of occlusal force on appropriate optical interocclusal registration in clinical practice, considering periodontal ligament and jawbone deformation. Forty participants with natural, healthy dentition were enrolled (19 men and 21 women; mean age, 27.7 ± 2.0 years). A TRIOS3 intraoral scanner was used to scan the right lateral first premolar to the second molar areas of the upper and lower jaws. During scanning for interocclusal registration, participants were instructed to "bite normally," "bite lightly," and "bite strongly" to obtain data for the three occlusal patterns. The standard triangulated language (STL) data for each occlusion condition were superimposed using the appropriate software, following which the tooth displacement was calculated. The conventional method was also used to record the occlusal contact area for a silicone model using a dental contact analyzer. Tooth displacement was significantly lower for the strong-bite condition than for the weak-bite condition (0.018 mm vs. 0.028 mm, P<0.05). As the occlusal force increased, the occlusal contact area also increased, and significant differences were observed among the different occlusal conditions (P<0.05). Occlusal contact area changed depending on the bite force when using the silicone impression or optical intraoral scanning methods. Moreover, using optical impression methods in "strong bite force" may reduce the deviation and allow for stable interocclusal registration.

Comparison Between Interocclusal Registration Using Silicone Bite Registration Material and Intraoral Scanner on Clenching Strength.

To clarify the influence of clenching strength on interocclusal registration using an intraoral scanner (IOS). The study includes eight volunteers as subjects, and the two experimental conditions were light clenching (LC) and 40% maximum voluntary clenching (MVC). Conventional silicone bite registration and an IOS were used for comparison. Occlusal contact areas (OCAs) for different clenching strengths were compared, along with variation of measured values (VMVs) between recording methods. Significant differences were observed between conditions on OCA and between methods on VMV. Clenching strength influenced interocclusal registration using IOS.

Evaluation of dimensional stability, compressive resistance, and detail reproduction of thermoplastic resin (BDIMPRESS), elastomeric and composite bite registration material: An in vitro study.

The fabrication of an accurate prosthesis depends mainly on precise recording of the maxillo-mandibular relationship of the patient and transferring it to the articulator. BDIMPRESS is a new thermoplastic material that has been proposed as a potential material to be used as an inter-occlusal registration, but there has been no literature evidence regarding its application as a bite registration. The main purpose of this study is to evaluate and compare the dimensional stability, detail reproduction, and compressive resistance of new interocclusal recording material with other two commonly used materials. In Vitro Comparative study. The study was conducted according to ADA Specification standards of testing for dimensional stability, detail reproduction and compressive resistance. Specimens were prepared for three different materials (Thermoplastic resin, Polyvinyl siloxane, and Bis- acrylic) with 12 samples each. One way ANOVA was done for statistical analysis. Polyvinyl siloxane material was dimensionally stable (mean at 1 hr: 24.928 mm; 24 hrs: 24.919 mm & 48 hrs: 24.912 mm) followed by Bis- acrylic material (mean at 1 hr: 24.851 mm; 24 hrs: 24.825 mm & 48 hrs: 24.815 mm). On one way ANOVA, strong significance was observed between groups (P = 0.00). Thermoplastic resin showed higher amount of detail reproduction with 10 (out of 12 samples) samples showing satisfactory results. While bis- acrylic material showed the least compressive resistance (Strain %: 0.484%; Displacement- 0.0990mm). One-way ANOVA showed presence of significance between the groups (P = 0.024). Polyvinyl siloxane showed superior dimensional stability, thermoplastic resin showed better detail reproduction and bis- acrylic showed high resistance to compression over other materials.

Comparison of accuracy in digital and conventional cross-mounting

Statement of problemThe use of digital interocclusal registration scans for virtual articulation and mounting has been studied extensively; however, the accuracy of the cross-mounting procedures in a digital workflow is not well understood. PurposeThe purpose of this in vitro study was to compare the accuracy of digital and conventional cross-mounting by measuring the 3-dimensional deviation at each step of sequential cross-mounting. Material and methodsA set of reference casts and complete arch interim restorations was prepared for complete arch complete-coverage restorations, hand-articulated, and mounted in an articulator. The reference casts were then scanned with and without the interim restorations to generate 4 reference casts for cross-mounting. For the conventional group, 15 sets of the 4 casts were printed. Polyvinyl siloxane interocclusal registration records were made of the reference casts for each set, and casts were sequentially cross-mounted. For the digital workflow, 15 sets of bilateral interocclusal registration scans were made of the mounted reference casts and used to align the cast scans. Three-dimensional deviations at 2 anterior and 2 posterior points were recorded between the experimental mountings and the reference casts on each set of casts. Nonpaired t test and analysis of variance (ANOVA) were used to compare the average discrepancy between the 2 groups, and the pooled anterior versus posterior discrepancies were compared (α=.05). ResultsA significant difference was found between conventional and digital cross-mounting procedures (P<.001), but no significant difference was found in either group, conventional (P=.116) or digital (P=.987), at each step of the sequential mountings. The mean ±standard deviation at the final set of related casts in the conventional workflow was 201.6 ±137.0 μm and that in the digital group was 50.3 ±47.5 μm, with a significant difference between anterior and posterior deviations in the digital group (P=.028), but not in the conventional group (P=.143). The mean ±standard deviation anterior conventional deviation was 175.6 ±119.2 μm and that in the digital group was 36.9 ±30.9 μm. The mean ±standard deviation posterior conventional deviation was 227.6 ±50.2 μm and that in the digital group was 63.7 ±57.2 μm. ConclusionsDigital cross-mounting was more accurate than conventional cross-mounting, although increased deviation was found in the anterior region compared with the posterior region.

In vivo precision of digital static interocclusal registration for full arch and quadrant arch scans: a randomized controlled clinical trial

BackgroundClinical studies comparing the accuracy of digital and conventional records for static interocclusal registration are lacking. Therefore, the purpose of this clinical study was to assess the precision of digital interocclusal registration compared to conventional registration for full arch and quadrant arch conditions.MethodsNine individuals with complete natural dentition were enrolled in this study. Each participant received digital scans, conventional impressions, and static interocclusal records according to the following groups: group DF, full arch digital scans and bilateral buccal scans with Medit i700 intraoral scanner (IOS); group DQ, quadrant arch digital scans and unilateral buccal scans with Medit i700 IOS; group CF, full arch polyvinyl siloxane (PVS) impressions and PVS interocclusal records; group CQ, quadrant arch PVS impressions and PVS interocclusal records. For group CF and group CQ, the impressions were poured, mounted with the silicone bites, scanned with a laboratory scanner, and articulated virtually with buccal scans with the laboratory scanner. In each group, each participant received three interocclusal records to repeat the virtual articulation three times and the articulated models were saved as STL files. The STL files were imported into a 3D-processing software to calculate the discrepancies between repeated measures using best-fit-alignment method. The significance between the study groups was calculated with two-tailed paired t-test at P < 0.05.ResultsFor full arch, group DF showed significantly better precision with a mean value of 31 ± 19 µm compared to 204 ± 81 µm for group CF (P = 0.0003). Similarly, for quadrant arch, group DQ showed significantly better precision with a mean value of 18 ± 6 µm compared to 255 ± 136 µm for group CQ (P = 0.0009). No significant difference in precision was found between quadrant arch and full arch when the digital or the conventional method was used.ConclusionsThe digital approach had significantly better precision for static interocclusal registration compared to the conventional method in both full and quadrant arch situations.Trial Registry This clinical trial was registered on 06/07/2022 in the Pan African Clinical Trial Registry database, the number for the registry is PACTR202207648490275.

Remontagem clínica e ajuste oclusal de próteses totais convencionais em articulador semiajustável

The polymerization process of total dentures causes dimensional changes, making it necessary to remounting these prostheses in a semi-adjustable articulator (ASA) to perform the occlusal adjustment. The objective of this study is to report a clinical case of oral rehabilitation with conventional full dentures, which was performed by the clinical remounting of the prostheses in ASA to perform the occlusal adjustment. A 72 years old male patient sought dental care at the Polyclinic of the State University of Amazonas. After anamnesis, extra and intraoral clinical examinations were indicated for conventional full dentures. After anatomical and functional impressions, working models were obtained, on which orientation plans were made. From the individualization of the upper orientation plane, registration of the facial arch and determination of intermaxillary relations, the models were assembled in ASA. After selection, assembly and aesthetic and functional testing of artificial teeth, the prostheses were polymerized, finishing and polishing. During the installation of the prostheses, there were few occlusal contacts and an anterior open bite. With the prostheses positioned on the edges, the facial arch was recorded to remounting the upper prosthesis in ASA and interocclusal registration in the central relation position for remounting of the lower prosthesis. The occlusal adjustment was performed by means of selective wear to obtain the correct centric and eccentric occlusal contacts. Clinical remounting of total prostheses in ASA is an efficient procedure for performing occlusal adjustment and obtaining bilateral balanced occlusion.

Three-dimensional analysis of the outcome of different scanning strategies in virtual interocclusal registration.

The purpose of this in vitro study was to assess whether scanning strategies of virtual interocclusal record (VIR) affect the accuracy of VIR during intraoral scanning. Five pairs of reference cubes were added to the digital upper and lower dentitions of a volunteer, which were printed into resin casts. Subsequently, the resin casts were articulated in the maximal intercuspal position in a mechanical articulator and scanned with an industrial computed tomography system, of which the VIR was served as a reference VIR. The investigated VIR of the upper and lower jaws of the resin master cast were recorded with an intraoral scanner according to 9 designed scanning strategies. Then, the deviation between the investigated VIRs and reference VIR were analyzed, which were measured by the deviation of the distances of six selected reference points on the upper reference cubes in each digital cast to the XY-plane between the investigated VIRs and reference VIR. For the deviation in the right posterior dentitions, RP group (only scanning of right posterior dentitions) showed the smallest deviation. Besides, BP group (scanning of bilateral posterior dentitions) showed the smallest deviation in the left posterior dentitions. Moreover, LP group (scanning of left posterior dentitions) showed the smallest deviation in the anterior dentitions. For the deviation of full dental arches, BP group showed the smallest deviation. Different scanning strategies of VIR can influence the accuracy of alignment of virtual dental casts. Appropriate scanning strategies of VIR should be selected for different regions of interest and edentulous situations.

Accuracy and dimension stability of scannable versus conventional interocclusal registration materials: An in vitro study

Statement of problemScientific data to support scannable and computer-aided design and computer-aided manufacturing (CAD-CAM)-compatible interocclusal registration materials are lacking. PurposeThe purpose of this in vitro study was to evaluate the ability of different registration materials (conventional versus scannable) to record maxillary-mandibular relationships and compare the dimensional stability of these records after storage times of 1 hour and 48 hours. Material and methodsSix groups of interocclusal registration materials were tested: 3 conventional (Registrado X-tra, Futar D Fast, and O-Bite) and 3 scannable (Registrado Scan, Futar Cut & Trim Fast, and O-Bite Scan). Eight registrations were made for each group by using a custom-made device with a dial gauge to measure vertical discrepancies. Records were stored at room temperature, and discrepancies measured after 1 hour and 48 hours. The data were statistically analyzed with the Wilcoxon test with respect to time and the Kruskal-Wallis test with respect to materials, followed by the Mann-Whitney test with the Bonferroni-Holm correction (α=.05). ResultsThe median vertical discrepancies ranged from -2 μm (FS) to 11 μm (O-Bite) after 1 hour and from 3 μm (Futar Cut & Trim Fast) to 13 μm (Registrado X-tra and O-Bite) after 48 hours. A statistically significant difference (P<.001) was found between the results after 1 hour and 48 hours for all materials. All scannable interocclusal registration materials showed significantly lower vertical discrepancies than the corresponding conventional materials after 1 hour and 48 hours (P<.05). ConclusionsAll registration materials showed vertical discrepancies that might be clinically acceptable. Vertical discrepancies increased after 48 hours of storage for all materials but were still clinically acceptable.

3D Virtual Patient Representation for Guiding a Maxillary Overdenture Fabrication: A Dental Technique.

This report describes a technique to obtain a 3D virtual representation of a maxillary edentulous patient guided by an additively manufactured intraoral scan body. The intraoral scan body incorporated a custom tray and occlusion rim which facilitated the acquiring of a digital definitive cast, maxillary occlusion rim position, interocclusal registration, and guided the integration of the facial scans. The technique simplified the design and manufacturing of the maxillary overdenture.

Additively manufactured scan body for transferring a virtual 3-dimensional representation to a digital articulator for completely edentulous patients

A technique is described for obtaining a virtual 3-dimensional representation of completely edentulous patients with the virtual definitive casts mounted on the virtual articulator. An additively manufactured intraoral scan body was developed to record the definitive maxillary and mandibular casts and gothic arch interocclusal registration. The intraoral scan body guided the integration of the digital definitive casts and facial scans to obtain the virtual 3-dimensional patient’s representation and facilitated the transfer of the definitive casts to the virtual articulator.

Three-dimensional analysis of the accuracy of conventional and completely digital interocclusal registration methods

Statement of problemCompared with the frequent investigations into the accuracy of digital intraoral scans, studies analyzing digital determinations of jaw relationships based on intraoral scans are scarce. PurposeThe purpose of this in vitro study was to present an optical 3-dimensional method for analyzing deviations in static occlusion and to compare the accuracy of conventional and digital interocclusal registrations. Material and methodsA Frasaco jaw model was duplicated, articulated, and scanned with a high-precision industrial scanner, and the data were stored in a virtual standard tessellation language (STL) format, which served as the reference model. Fifteen paired mandibular and maxillary models were scanned with a digital intraoral scanner in the completely digital workflow (IOS group). Forty-five paired gypsum casts were poured from polyvinyl siloxane (PVS) impressions and associated with 2 different PVS registration materials. These casts were digitized with a laboratory scanner and grouped as follows (n=15/group): PVS group, conventional Futar D interocclusal record; sPVS group, conventional Futar Scan interocclusal record; and the AIR group, partially digital antagonist scan of the Futar Scan interocclusal record. The axes (X, Y, Z, and XYZ) of each paired model were aligned to those of the reference model by 3-dimensional superimposition, and deviations were calculated. To determine the ideal zero position, a best-fit over the mandibular teeth between the reference model and the actual model was estimated. Next, a second best-fit was determined between the maxillary models to determine the actual position of the mandibular model. The different registration methods were compared with the Mann–Whitney U test (α=.05). ResultsIn the IOS group, the interocclusal registration caused a mandibular deviation of 0.05 ±0.04 mm (mean ±standard deviation). This fit was better than those of conventional registrations with inserted interocclusal registration materials (PVS group and sPVS group), which caused mean z-axis deviations of 0.41 ±0.46 mm and 0.44 ±0.32 mm (P<.001), with the deviations leading to elevation of the mandibular model. The partially digital workflow with a scannable registration material (AIR group) showed significantly larger deviations in the x-axis (0.15 ±0.08 mm; P=.042) compared with the IOS group. No significant difference was observed in the total deviation between the IOS and the AIR groups. Both groups showed significantly smaller deviations than the conventional registration methods (P<.001 for the IOS group and P=.023 for the AIR group). ConclusionsIn comparison with maxillary and mandibular alignment using conventional interocclusal registration materials, digital interocclusal registrations showed greater accuracy in evaluating complete jaw models and can be recommended for clinical use. Additionally, the partially digital workflow with an antagonist scan of the interocclusal record provided acceptable results.

Assessment of Sagittal Condylar Guidance with Protrusive Inter-occlusal Method, Panoramic Radiographs, and Lateral Cephalogram: A Comparative Study

Condylar guidance can be determined using the clinical and radiographic methods. The present study was conducted to determine condylar guidance using the protrusive interocclusal wax method, panoramic radiographs, and lateral cephalogram. The aim of the study was to compare the correlation between sagittal condylar guidance with protrusive interocclusal method, panoramic radiographs, and lateral cephalogram. The present study was conducted on 82 dentulous subjects (males 41, females 41). In all subjects, interocclusal registration values and condylar guidance values were measured using panoramic radiographs and lateral cephalograms. The mean ± SD protrusive interocclusal registration value on the left side was 34.01 ± 1.2 mm and 34.08 ± 1.4 mm on the right side. The panoramic radiographs showed 35.12 ± 1.6 mm on the left side and 35.16 ± 1.7 mm on the right side. The mean ± SD protrusive interocclusal registration values on the left side was 34.01 ± 1.2 mm on the left side and 34.08 ± 1.4 mm on the right side. Lateral cephalogram showed 34.35 ± 1.3 mm on the left side and 34.67 ± 1.6 mm on the right side. There was a significant difference between the methods (p < 0.05). Sagittal condylar guidance can be evaluated using protrusive interocclusal method. Along with it, other methods such as panoramic radiographs and lateral cephalogram may also be used for recording condylar guidance. Lateral cephalogram and panoramic radiographs may be reliable in determining condylar guidance, which can be used in orthodontic treatment planning.