Maxillary Cast Research Articles

Evaluation of the Distortion of Essix Retainer Formed From Biostar Machine Using Intraoral Digital Scans: An In Vitro Study.

Introduction Retention is essential to prevent unwanted tooth movement due to growth changes, to allow the gingival and periodontal tissues affected by orthodontic treatment to realign, and to stabilize teeth that have been moved to potentially unstable positions, thus reducing the risk of relapse. This study aimed to evaluate the distortion of Essix retainers over time to enhance their retention and stability. Methods Patients who visited the Department of Orthodontics and Dentofacial Orthopedics at Ranjeet Deshmukh Dental College & Research Centre, Nagpur, India, after completing their orthodontic treatment were included in the study, according to the established inclusion and exclusion criteria. A total of 26 patients participated. Each patient received an Essix retainer fabricated from a Duran+ Biostar round sheet (1 mm thickness) using a Biostar machine based on their post-debonded maxillary cast. The patients were instructed on the correct insertion and removal of the Essix retainer. The inner surface of the retainers was scanned at one month, three months, and six months using an intraoral digital scanner. These scans were analyzed and compared for distortion at different time intervals using Medit software. Results The Essix retainers exhibited varying degrees of distortion at different time intervals. Notably, distortion was more significant in the posterior region compared to the anterior region. Additionally, distortion increased over time, with the least amount observed at one month and progressively worsening by the sixth month. Specifically, the average distortion in the posterior region ranged from 0.133 mm after the first month to 0.304 mm after six months. In contrast, the average distortion in the anterior region was lower, ranging from 0.057 mm at one month to 0.068 mm at six months. Conclusions Distortion was more pronounced on the posterior surface of the Essix retainer compared to the anterior region.

A Comparative Evaluation of Real-Time Guided Dynamic Navigation and Conventional Techniques for Post Space Preparation During Post Endodontic Management: An In Vitro Study.

The three-dimensional (3D) dynamic navigation system (DNS; Navident, ClaroNav Technology, Toronto, ON) is a revolutionary technique in endodontics that offers superior precision and efficiency compared to existing techniques for post space preparation. The aim is to evaluate and contrast the efficacy and efficiency of the DNS with conventional post space preparation techniques. This assessment considers severalparameters, notably canal deviation (global coronal and apical deviation and angular deflection), duration of the procedure, and total volumetric loss of instrumented root canal and volumetric loss of instrumented root canal above 4 mm from the apex. Freshly extracted maxillary central incisors were chosen for this study. A total sample size of 60 (n) was included. The extracted teeth samples were divided into two groups: 3D DNS (group I; n = 30)and conventional techniques (group II; n = 30). The samples were taken, and 50% of the crown structure was reduced for post space preparation to ensure standardization between thetwo groups. The samples were root canal-treated and mounted in a 3D-printed maxillary cast. Preoperative micro-computed tomography (micro-CT) and cone-beam computed tomography (CBCT) were taken for both groups.For group I, post space preparation was conducted with the DNS, which provided comprehensive guidance. The procedure was stopped when post space preparation was 4 mm short of the apex, as indicated in the system display. For group II, post space preparation was done without the guidance of DNS. Time taken for the procedure was assessed using a timer; canal deviation was evaluated using CBCT analysis, and volumetric loss was estimated using micro-CT analysis. The dynamic navigation group achieves significantly more precise outcomes in post space preparation than the conventional technique. The DNS group has significantly lesser global coronal and apical deviation and angular deflection compared to the conventional group (p < 0.05). The DNS group has reduced the volumetric loss of instrumented root canals compared to the conventional group (p < 0.05). Furthermore, the DNS group requires significantlyless time than the conventional method, with a mean difference of about 10.567 minutes (p < 0.05). Implementing dynamic navigation improves precision in post space preparation, with a notable reduction in canal deviation and volumetric loss and a decrease in procedure time compared to the conventional method.

Homemade CAD-CAM surgical guide for palatal mini-screw insertion for maxillary molar distalization providing anchorage. A two times original protocol

Temporary Anchorage Devices have revolutionized our approach to anchorage management. However, their placement may carry risks, such as root perforation, damage to the periodontal ligament, buccal-nasal communication, etc. The aim of this article is to describe an original protocol in two times for the placement of a palatal mini-screw through guided surgery using a guide created by Computer-Aided Design and Manufacturing (CAD/CAM) followed by the transfer of placement information to the laboratory for the fabrication of a Custom Medical Device (CMD) for distalization. A two-stage protocol is described and illustrated step by step. Phase 1 comprises 7 steps (including superimposition of maxillary cast and profile teleradiography, surgical tray design), followed by phase 2, which involves 3 final steps (including production of impression for laboratory, production of laboratory model with transfer of mini-screw position). Although the position of the mini screws remains precise, a discrepancy between the planning and the intraoral situation exists. The addition of a second step therefore enables the distalization appliance to be fitted precisely and without pitfalls. Finally, this protocol ensures safe placement, making work easier for the practitioner and, ultimately, for the patient. In a two-stage process, the placement of palatal mini screws through guided surgery using a guide created by CAD/CAM followed by the transfer of this information to the laboratory for the fabrication of a CMD for distalization proves to be a relevant approach.

An overview of the different digital facebow methods for transferring the maxillary cast into the virtual articulator.

The purposes of this study were to classify the described digital facebow techniques for transferring the maxillary cast into the semi-adjustable virtual articulator based on the digital data acquisition technology used and to review the reported accuracy values of the different digital facebow methods described. Digital data acquisition technologies, including digital photographs, facial scanners, cone beam computed tomography (CBCT) imaging, and jaw tracking systems, can be used to transfer the maxillary cast into the virtual articulator. The reported techniques are reviewed, as well as the reported accuracy values of the different digital facebow methods. Digital photographs can be used to transfer the maxillary cast into the virtual articulator using the true horizontal reference plane, but limited studies have assessed the accuracy of this method. Facial scanning and CBCT techniques can be used to transfer the maxillary cast into the virtual articulator, in which the most frequently selected references planes are the Frankfort horizontal, axis orbital, and true horizontal planes. Studies analyzing the accuracy of the maxillary cast transfer by using facial scanning and CBCT techniques are restricted. Lastly, optical jaw trackers can be selected for transferring the maxillary cast into the virtual articulator by using the axis orbital or true horizontal planes, yet the accuracy of these systems is unknown. Digital data acquisition technologies, including digital photographs, facial scanning methods, CBCTs, and optical jaw tracking systems, can be used to transfer the maxillary cast into the virtual articulator. Studies are needed to assess the accuracy of these digital data acquisition technologies for transferring the maxillary cast into the virtual articulator.

Influence of base designs on the manufacturing accuracy of vat-polymerized diagnostic casts using two different technologies

Statement of problemDiagnostic casts can incorporate different base designs and be manufactured using different vat-polymerization technologies. However, the influence of the interrelation between the base design and the 3D printing technology on the casts' final accuracy remains unclear. PurposeThe purpose of this in vitro study was to assess the influence of different base designs of 3D printed casts on the accuracy of 2 vat-polymerization technologies. Material and methodsA digital maxillary cast was obtained and used to generate 3 different base designs: solid (S group), honeycombed (HC group), and hollow (H group). The HC and H groups were subdivided based on the wall thickness of the cast design, resulting in 2 subgroups with thicknesses of 1 mm (HC1 and H1) and 2 mm (HC2 and H2) (N=100, n=10). Eleven reference cubes were added to each specimen for subsequent measurements. Specimens were manufactured by using 2 vat-polymerization 3D printers: Nextdent 5100 (ND group) and Sonic Mini 4K (SM4K group) and a resin material suitable for both 3D printers (Nextdent Model 2.0). A coordinate measuring machine quantified the linear and 3-dimensional discrepancies between the digital cast and each reference specimen. Trueness was defined as the average absolute dimensional discrepancy between the virtual cast and the specimens produced through additive manufacturing (AM), while precision was delineated as the standard deviation in dimensional discrepancies between the digital cast and the AM specimens. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U pairwise comparison tests (α=.05). ResultsFor the NextDent group the trueness ranged from 21.83 µm to 28.35 µm, and the precision ranged from 17.82 µm to 37.70 µm. For the Phrozen group, the trueness ranged from 45.15 µm to 64.51 µm, and the precision ranged from 33.51 µm to 48.92 µm. The Kruskal-Wallis test showed significant differences on the x-, y-, and z-axes and in the 3D discrepancy (all P<.001). On the x-axis, the Mann-Whitney U test showed significant differences for the Phrozen group between the H-2 and H-1 groups (P=.001), H-2 and S groups (P<.001), and HC-2 and S groups (P=.012). On the y-axis, significant differences were found in the Phrozen group between the H-2 and H-1 groups (P=.001), the H-2 and S, H-1 and HC-1, and HC-1 and S groups (P<.001), the H-1 and HC-2 groups (P=.007), and the HC-2 and S groups (P=.009). The NextDent group exhibited significant differences, particularly among the HC-1 and H-2 groups (P=.004), H-1 (P=.020), and HC-2 (P=.001) groups; and on the z-axis significant differences were found in the Phrozen group between the H-2 and H-1 and S groups and the HC-2 group and H-1 and S groups (both P<.001). In the NextDent group, significant differences were found between the H-2 and HC-2 (P=.047) and HC-1 (P=.028) groups. For the 3D discrepancy analysis, significant differences were found in the Phrozen group between the H-2 and H-1 and S groups (P<.001), the H-1 and HC-2 groups (P=.001), the S and HC-1 and HC-2 groups (P<.001), and the H-1 and HC-1 groups (P=.002). In the NextDent group, significant differences were observed between the H-2 and HC-1 groups (P=.012). ConclusionsThe accuracy of digital casts depends on the manufacturing trinomial and base design of the casts. The honeycomb and hollow based designs provided the highest accuracy in the NextDent and Phrozen groups respectively for the material polymer tested. All specimens fell in the clinically acceptable range.

Dimensional Stability of Additively Manufactured Diagnostic Maxillary Casts Fabricated with Different Model Resins.

To evaluate the effect of model resin type and time interval on the dimensional stability of additively manufactured diagnostic casts. Ten irreversible hydrocolloid impressions and 10 impressions from an intraoral scanner were made from a reference maxillary stone cast, which was also digitized with a laboratory scanner. Conventional impressions were poured in type III stone (SC), while digital impressions were used to additively manufacture casts with a nanographene-reinforced model resin (GP) or a model resin (DM). All casts were digitized with the same laboratory scanner 1 day (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4) after fabrication. Cast scans were superimposed over the reference cast scan to evaluate dimensional stability. Data were analyzed with Bonferroni-corrected repeated measures ANOVA (α = .05). The interaction between the main factors (material type and time interval) affected anterior teeth deviations, while the individual main factors affected anterior teeth and entire-cast deviations (P ≤ .008). Within anterior teeth, DM had the lowest deviations at T3, and GP mostly had lower values at T2 and lower deviations at T3 than at T0 (P ≤ .041). SC had the highest pooled anterior teeth deviations, and GP had the highest pooled entire cast deviations (P < .001). T3 had lower pooled anterior teeth deviations than at T0, T1, and T4, and higher pooled entire cast deviations than T1 were demonstrated (P ≤ .027). The trueness of nanographene-reinforced casts was either similar to or higher than that of other casts. Dimensional changes were acceptable during the course of 1 month.

Clinical evaluation of three different anterior reference points on protrusive condylar guidance angle using a semi adjustable articulator and lateral cephalogram

Background: Studies had shown that different anterior reference points can mount the maxillary cast in variable position in the articulator which may affect the protrusive condylar guidance angle on setting the semi adjustable articulator. So there is a need for search of reliable anterior reference point in orienting the maxillary cast on the articulation for accurate prosthesis fabrication. Aim: The aim of this study was to determine the effect of 3 different anterior reference points Orbitale, Orbitale minus 7mm, 36mm from the incisal edge of maxillary central or lateral incisor on the protrusive condylar guidance values registered on Hanau wide vue articulator and compare it to the protrusive condylar guidance angle obtained from lateral Cephalometric tracings. Materials and methods: A total of 30 healthy human subjects were randomly selected for this study from volunteer dental students. Orbitale, Orbitale minus 7mm, 36mm from the maxillary incisal edge of the subjects were the three anterior reference points used for facebow transfer using Hanau springbow. With the help of protrusive records, articulation was done in Hanau wide vue articulator using this record and condylar inclination values were noted on right side and left side.Three sets of lateral cephalometric radiographs were taken in maximum intercuspation and protrusive position, traced manually and values tabulated for all 30 subjects. Results: Mean value of orbitale is highest and mean value of 36mm from the maxillary incisal edge is lowest. Conclusion: Orbitale can be used as a reliable anterior reference point in facebow transfer using hanau wide vue articulator.

Evaluating the Impact of Scan Body Angulation and Geometric Attachments on the Accuracy of Complete-Arch Digital Implant Impressions: A Comparison of Two Intraoral Scanners.

To investigate the effects of scan body (SB) angulation and geometric attachments on the deviations of complete-arch digital implant impressions obtained using intraoral scanners (IOSs), in relation to the gold-standard desktop scanner. Two intraoral scanners (iTero and Omnicam), two scan body angulations (0 degrees and 30 degrees), and geometric attachments (GAs) for the SBs were investigated. SBs were attached to an edentulous maxillary cast with the following implant analogs: parallel 0-degree at positions #13, #23, and #26, and 30-degree posteriorly tilted at position #16. The cast was digitized using a reference desktop scanner, followed by ten consecutive digital scans using each IOS (five scans with GAs and five without GAs, n = 20). Meshes obtained from the IOS scans were superimposed on the master reference mesh. Linear distance and 3D surface deviations from the reference mesh were calculated. A three-way multivariate analysis of variance (MANOVA) was employed to assess the effects of angulation, IOS type, and GAs on the combined dependent variables (α = 0.05). No significant three-way interaction was observed between IOS type, SB angulation, and GAs for combined deviations from the reference scan (p = 0.56). Simple main effect analysis revealed that iTero exhibited significantly lower mean 3D surface and linear deviations than Omnicam (p<0.05). Additionally, the use of GAs significantly reduced deviations (p<0.001), with mean deviation reductions for both scanners ranging from 26-33 micrometers (μm) for 3D deviations and 15-21μm for linear distance deviations. No differences were found between angled and parallel SBs regarding 3D surface and linear distance deviations (p≥0.05). iTero demonstrated significantly smaller deviations, and the use of GAs led to significantly reduced distance and 3D surface deviations. SB angulations did not impact scan deviations. This article is protected by copyright. All rights reserved.

Correlation Between Maxillary Anterior Teeth and Common Facial Measurements.

The symmetry between maxillary anterior teeth and the face holds significant importance. This study assessed and analyzed the relationship between facial parameters and anterior teeth in the maxillary arch of male and female subjects. Specifically, individual width and combined width (CW) measurements of the maxillary anterior teeth were investigated. This study involved a total of 150 dentate Yemeni subjects (74 men and 76 women), whose ages ranged from 18 years old to 30 years old. A maxillary cast was created, and two digital photographs of the face of each subject were taken and analyzed. Digital calipers and AutoCAD were used to gather measurement data of the dental parameters (intercanthal distance [ICD], interpupillary distance [IPD], interalar width [IAW], intercommissural width [ICW], and bizygomatic width [BZW]) and facial parameters (profile distance). Significant correlations were found for the following: IPD and width of six maxillary anterior teeth of each of the study subjects; ICD and their central incisors; and BZW and their canine width measurements. In contrast, IAW and ICW were not correlated with all tooth measurements. Linear regression findings showed that the CW measurement of the four incisors was significantly correlated with all facial parameter measurements, excluding the ICW and IAW in females and the IAW, ICW, and profile distance in males. The IPD and ICD of males and females may be used to determine their CW measurements. The BZW and IPD of males can be used to take precise anthropological measurements of the width of the central canines and incisors. Meanwhile, the IPD distance of females can be used to assess the central and lateral incisor widths.

In vitro study of the accuracy and efficiency of wireless intraoral scanners at various battery levels

ObjectivesTo determine the trueness and precision of 2 wireless intraoral scanners (IOSs) under various battery levels, and assess scanning efficiency. MethodsA maxillary cast with 4 metal spheres attached was fabricated. Two wireless IOSs (TRIOS 3 and TRIOS 4) were evaluated under 3 battery levels (1–30%, 31–60%, and 61–100%; n = 30). Six horizontal distances and 1 vertical distance were measured between 4 spherical centers and 1 generated plane. The distance deviations were determined with a coordinate-measuring machine data set. Kruskal-Wallis and Levene tests were used to analyze trueness and precision. Scan time and the number of three-dimensional (3D) images captured were analyzed by using a 2-way analysis of variance. ResultsIn terms of trueness and precision, no significant differences were found at various battery levels over the majority of the measured distances. TRIOS 4 demonstrated better trueness than TRIOS 3 for cross-arch scan. The 61–100% battery level resulted in the shortest scan time and the least number of 3D images captured (p < 0.001). Scan time and number of 3D images captured were strongly correlated for TRIOS 3 (r = 0.66) and TRIOS 4 (r = 0.89). ConclusionsChanges in battery level had no impact on the trueness and precision of TRIOS 3 and TRIOS 4. High battery level IOSs resulted in faster scans and fewer 3D images captured with less storage space. TRIOS 4 scanned faster, captured fewer images, and demonstrated better trueness than TRIOS 3. Clinical significanceAlthough all battery levels of wireless IOSs provide comparable trueness and precision, a wireless IOS with a high battery level is more time efficient than one with a low battery level in complete-arch scan.

Influence of interdental spaces and the palate on the accuracy of maxillary scans acquired using different intraoral scanners.

To assess the influence of interdental spaces and scanning the palate on the accuracy of maxillary scans acquired using three intraoral scanners (IOSs). A virtual completely dentate maxillary cast without interdental spaces was obtained and modified to create 1, 2, and 3mm of interdental spacing between the anterior teeth. These three files (reference standard tessellation language files) were used to print three reference casts. The reference casts were scanned using three IOSs: TRIOS4, iTero Element 5D, and Aoralscan2. Three groups were created based on the interdental spaces: 0, 1, 2, and 3mm (n = 10). The groups were subdivided into two subgroups: no palate (NP subgroup) and palate (P subgroup). The reference STL files were used to measure the discrepancy with the experimental scans by calculating the root mean square (RMS) error. Three-way analysis of variance (ANOVA) and post hoc Tukey pairwise comparison tests were used to analyze trueness. The Levene test was used to analyze precision (α = 0.05). Trueness ranged from 91 to 139μm and precision ranged from 5 to 23μm among the subgroups tested. A significant correlation was found between IOS*group (p<0.001) and IOS*subgroup ( p<0.001). Tukey test showed significant trueness differences among the interdental spaces tested (p<0.001). The 1- and 2-mm groups obtained better trueness than the 0- and 3-mm groups (p<0.001). An 11μm mean trueness discrepancy was measured among the different interdental space groups tested. The P subgroups demonstrated significantly higher trueness when compared to the NP subgroups (p<0.001). The discrepancy between the maxillary scans with and without the palate was 4μm. Significant precision discrepancies were found (p = 0.008), with the iTero group showing the lowest precision. Interdental spaces and incorporation of the palate on maxillary intraoral scans influenced trueness and precision of the three IOSs tested. However, the scanning discrepancy measured may be of no clinical relevance.

Evaluation of Distortion in the Posterior Palatal Seal Area of Maxillary Cast by Different Adaptation Techniques of Denture Bases.

To evaluate and compare the amount of distortion in the posterior palatal seal area in V-shaped and U-shaped palatal form of maxillary cast by different adaptation techniques of maxillary denture bases. A total of 60 stone casts were made, out of which 30 identical stone casts of U-shaped palatal form and 30 identical stone casts of V-shaped palatal form of maxillary casts were prepared. The 30 stone casts of U-shaped palatal form and 30 stone casts of V-shaped palatal forms were divided into three groups for measurements to be done. Data were statistically analyzed by using two-way analysis of variance (ANOVA) without replication. Discrepancies of fit of dentures on U-shaped casts and V-shaped casts of Groups 1, 2, and 3 in transverse and sagittal sections were measured, and comparative statistical analysis between Group 1&2, Group 1&3, and Group 2&3 was done for statistical significant values. Discrepancy in the central region was maximum, and the anchoring methods Group 2 and Group 3 produced a significantly better adaptation than the conventional method (Group 1). The adaptations for V-shaped palate were better when compared with U-shaped palate in the central region.

Rehabilitation of Maxillary defect using Removable Maxillary Cast Partial Denture Hollow Prosthesis for managing Mucomycosis patient: A Clinical Case Report

&#x0D; Introduction: Mucormycosis is the fungal infection which especially affects immunocompromised patients. Case Report: In this case report, prosthetic rehabilitation of maxillary defect due to past mucormycosis in an uncontrolled diabetic patient was discussed by means of lightweight prosthesis by attaching a hollow occlusal shim to cast partial denture framework as absence of alveolar ridge on the defect side tends to increase the weight of the prosthesis which would have compromised the retention of the prosthesis. Conclusion: This technique is simple, economical and less time-consuming.

Comparison of denture base adaptation between additive and conventional fabrication techniques.

This in vitro study compared the adaptation of denture bases fabricated by injection molding (IM), compression molding (CM), liquid crystal display (LCD), and digital light processing (DLP) techniques. A definitive maxillary cast was duplicated using a silicone mold to create 40 gypsum casts that were laser scanned before any fabrication procedures were initiated. For the DLP and LCD groups, 20 denture bases (10 in each group) were virtually designed and manufactured referring to the digitalized data. For the CM and IM groups, 20 denture bases (10 in each group) were molded using gypsum models. A total of 40 gypsum models and their corresponding denture bases were scanned. The scanned intaglio surface of each denture base was superimposed on the scanned reference cast to compare the degree of tissue surface adaptation. The three-dimensional surface deviations of the total intaglio surface, denture border apex, palatal vault, and crest of the ridge were evaluated on the basis of the best fit algorithm technique using inspection software. The data were statistically analyzed using one-way ANOVA and Tukey's multiple comparison test (α=0.05). According to the superimposing results, for the total intaglio surface, the lowest deviation was present on the injection-molded group and the highest deviation occurred on the LCD group. For the palatal vault, the lowest deviation was present on the DLP group and the highest deviation occurred in the compression molded group. For the crest of the ridge, the lowest deviation was present in the injection-molded group and the highest deviation occurred in the LCD group. For the denture border apex, the lowest deviation was present in the DLP group and the highest deviation occurred in the LCD group. Maxillary denture bases fabricated using DLP and IM techniques showed higher surface adaptation than the bases fabricated using LCD and CM techniques. Among the conventional techniques, higher compatible dentures can be produced with IM; among the additive techniques, higher compatible dentures can be produced with DLP.

Differences in maxillomandibular relationship recorded at centric relation when using a conventional method, four intraoral scanners, and a jaw tracking system: A clinical study

Statement of problemDigital systems including intraoral scanners (IOSs) and optical jaw tracking systems can be used to acquire the maxillomandibular relationship at the centric relation (CR). However, the discrepancy of the maxillomandibular relationship recorded at the CR position when using digital methods remains uncertain. PurposeThe purpose of this clinical study was to compare the accuracy of the maxillomandibular relationship recorded at the CR position using a conventional procedure, 4 different IOSs, and an optical jaw tracking system. Material and methodsA completely dentate volunteer was selected. A Kois deprogrammer (KD) was fabricated. Six groups were created based on the technique used to obtain diagnostic casts and record the maxillomandibular relationship at the CR position: conventional procedures (CNV group), 4 IOS groups: TRIOS4 (TRIOS4 group), iTero Element 5D (iTero group), i700 wireless (i700 group), Primescan (Primescan group), and a jaw tracking system (Modjaw) (Modjaw group) (n=10). In the CNV group, conventional diagnostic stone casts were obtained. A facebow record was used to mount the maxillary cast on an articulator (Panadent). The KD was used to obtain a CR record for mounting the mandibular cast, and the mounted casts were digitized by using a scanner (T710) to acquire the reference scans. In the TRIOS group, intraoral scans were obtained and duplicated 10 times. The KD was used to obtain a bilateral virtual occlusal record at the CR position. To acquire the specimens of the iTero, i700, and Primescan groups, the procedures in the TRIOS4 group were followed, but with the corresponding IOS. In the Modjaw group, the KD was used to record and export the maxillomandibular relationship at the CR position. Articulated virtual casts of each group were exported. Thirty-six interlandmark linear measurements were computed on both the reference and experimental scans. The distances obtained on the reference scan were used to calculate the discrepancies with the distances obtained on each experimental scan. The data were analyzed by using 1-way ANOVA followed by the pairwise comparison Tukey tests (α=.05). ResultsThe trueness and precision of the maxillomandibular relationship record were significantly affected by the technique used (P<.001). The maxillomandibular relationship trueness values from high to low were iTero (0.14 ±0.09 mm), followed by the Modjaw (0.20 ±0.04 mm) and the TRIOS4 (0.22 ±0.09 mm) groups. However, the iTero, Modjaw, and TRIOS4 groups were not significantly different from each other (P>.05). The i700 group obtained the lowest trueness and precision values (0.40 ±0.22 mm) of all groups tested, followed by the Primescan grop (0.26±0.13 mm); however, the i700 and Primescan groups had significantly lower trueness and precision than only the iTero group (P<.05). ConclusionsThe trueness and precision of the maxillomandibular relationship recorded at the CR position were influenced by the different digital techniques tested.

Effect of implant scan body geometric modifications on the trueness and scanning time of complete arch intraoral implant digital scans: An in vitro study

Statement of problemThe effect of the surface geometry of implant scan bodies (ISBs) on the accuracy and scanning time of complete arch implant digital scans remains uncertain. PurposeThe purpose of this in vitro study was to evaluate whether geometric modifications on implant scan bodies (nonmodified, subtractively modified, and additively modified ISBs) affect the trueness and scanning time of complete arch intraoral implant digital scans. Material and methodsA completely edentulous maxillary cast with 2 anterior parallel and two 17-degree posteriorly tilted implant abutment analogs was prepared. A digitized reference was created from this cast with polyetheretherketone (PEEK) (CARES Mono Scanbody for screw-retained abutment) ISBs by using a desktop scanner (E3). Three different groups were created: nonmodified (NM group), subtractively modified (SM group), and additively modified (AM group). For the NM group, no modifications were made to the ISBs. For the SM group, 4 round-shaped grooves were created on the buccal, lingual, mesial, and distal sides. For the AM group, PEEK beads were printed and cemented on the same areas of the ISB of the SM group. Fifteen consecutive scans were captured with an intraoral scanner (TRIOS 3) for each group, and the scanning time was recorded. By using a metrology software program, scans of each group were superimposed on the reference file to determine the 3D surface, linear, and angular position discrepancies of each ISB. Repeated-measures analyses of variance followed by univariate analysis and Bonferroni multiple comparison tests were performed to analyze the data (α=.05). To compare the mean time among groups, 1-way analysis of variance was performed followed by the Tukey post hoc tests. ResultsSignificant 3D surface, linear, and angular position discrepancies were found when measuring trueness among the NM, SM, and AM groups (P<.001). Discrepancies in 3D surface deviation were highest for the AM group (0.266 ±0.030 mm), and the lowest mean angular deviation values were for the SM group (0.993 ±0.062 degrees). However, the mean scanning time was not significantly different among the groups tested (P=.237). ConclusionsFor complete arch intraoral implant digital scans, subtractive modifications on ISBs enhanced scanning trueness, while additive modifications on ISBs decreased scanning trueness. However, implant scan body geometric modifications did not affect scanning time.

Scanning accuracy with splinted and unsplinted implant scan bodies for the edentulous arch atimplant level: an in vitro study.

Accuracy of completely edentulous arch scanning with implant scan bodies has not been completely validated for intraoral scanners. For desktop laboratory scanners validations were found in the literature. The aim of this in vitro study was to compare the dimensional accuracy of scanning with splinted and unsplinted scan bodies on a completely edentulous maxillary arch with 6 implants. A maxillary edentulous master cast with 6 implants was used as control for all implant level impressions. 6 implants were digitally planned and placed at different angulation of 0, 0 17° and 30°. A contact coordinate measuring machine (CMM) was used to generate baseline linear measurements of the master cast. Four test groups included: 2 intraoral scanners Trios (3shape, Copenhagen, Denmark) and True Definition (3M ESPE, St Paul, MN), one industrial scanner Atos (Core optical 3D scanner) and one conventional impression group scanned with laboratory scanner Dental Wings 7 Series. Each scan recording was made with splinted and unsplinted scan bodies. Digital datasets of all measurements were compared with the CMM baseline values using PolyWorks® InnovMetric Software in order to assess the linear and angular deviations and determine the accuracy of complete arch digital impression. Factorial ANOVA showed significant effect with splinting, scanner type, inter-implant distance and implant angulation for linear deviations. Splinted scan bodies revealed elevated linear and angular deviation values for all scanners with significantly highest deviations for True Definition scanner. Significant correlation was found between inter-implant distance and linear deviation (r =0.45, P =<0.001) with increased linear deviations among all scanners, regardless of splinting. ( P <0.05). Significant effect on accuracy was seen for angular deviation with splinting, scanner type and implant angulation; significant difference was found between 0° and 30° implant angulation ( P =0.035) with more deviation with 30° implant angulation. The accuracy of the complete arch implant digital impression using splinted scan bodies was significantly reduced for measurements that crossed the arch midline. The digital impression technique using a broad splint design to connect scan bodies was not found to improve the scan accuracy for intraoral scanners.

Evaluation of Sagittal Inclination of Occlusal Plane and Horizontal Condylar Guidance Using Various Anterior Reference Points on Arcon and Nonarcon Articulators.

Aim:The aim of the study was to determine the effect of different anterior reference points during facebow transfer, on sagittal inclination of occlusal plane (SIOP) and horizontal condylar guidance (HCG) values obtained on arcon and nonarcon articulators.Materials and Methods:Facebow records of 25 participants were made and transferred to Hanau Wide-Vue (WV) and Hanau H2 (H2) articulators using conventional indirect transfer (CIT), superior annular groove (SAG), and inferior annular groove (IAG) as anterior reference points. Maxillary casts were mounted on each articulator followed by mandibular mountings. Protrusive interocclusal record was used to determine HCG, and SIOP was measured as an angle between the occlusal plane of mounted maxillary cast and upper member of the articulator. Both, HCG and SIOP were measured on a digital lateral cephalogram and the values obtained were compared with previously determined values from both the articulators. Intergroup comparison was done by analysis of variance and pair-wise comparison by Tukey post hoc test.Results:Values of SIOP significantly (P = 0.00) changed on both the articulators when CIT, SAG, and IAG were the anterior reference points. The ratio of SIOP and HCG on both articulators was comparable to that of the cephalogram for CIT, IAG, but it was substantially low for SAG.Conclusions:The variation of anterior reference point changes the value of SIOP recorded on Hanau WV and H2 articulators; however, it had no effect on HCG values recorded on both the articulators. The angle between SIOP and HCG changed with variations in superior-inferior position of the mountings on both articulators.

Comparative evaluation of sulcus/ vestibular depth by intraoral examination and on master cast/denture in completely edentulous cases

Context: Residual ridge resorption(RRR) affect the patient’s satisfaction with complete denture by decreasing the sulcus / vestibular depth, Aims: The aim of this study is to find the correlation between difference in sulcus / vestibular depth by intraoral examination and on master cast/ old denture with patient’s satisfaction from complete denture. Settings and Design: The study included old denture wearer and complete denture prosthesis made by different operators in the college. Methods and Material: The vestibular sulcus depths at 7 different sites in edentulous maxilla and 12 different sites in edentulous mandible and respective flange height in maxillary and mandibular denture were measured. Prevalidated questionnaire was used to measure the satisfaction of patients with denture. Statistical analysis used: Pearson correlation was done to find the correlation between satisfaction score and difference in sulcus / vestibular depth. Results: The difference in sulcus depth in maxilla with maxillary cast and mandible with mandibular master cast/ denture showed medium to large negative correlation with p value 0.01. The increase in difference will lead to decrease in satisfaction score of patients.

Implant-retained overdenture delivery in 2 visits with a digital workflow

The conventional method of fabricating implant-retained overdentures involves multiple steps and patient visits. However, the duplication of existing complete dentures could decrease the number of visits and increase patient satisfaction. An existing maxillary implant-retained overdenture was replaced for a 78-year-old man; the existing implant-retained overdenture and his face were scanned at the first visit. The scanned intaglio image was inverted to obtain a virtual maxillary cast and used to fabricate the metal framework of the replacement implant-retained overdenture. Prefabricated artificial teeth were arranged on a 3-dimensional trial denture created from the scan data of the existing implant-retained overdenture. The replacement implant-retained overdenture was fabricated on the metal framework by using the injection molding technique. By using these digital techniques, a stable and esthetic implant-retained overdenture was delivered in 2 visits.