A single procedure for the registration of maxillo-mandibular relationships and alignment of intraoral scans of edentulous maxillary and mandibular arches

A method to improve positioning of denture teeth on denture bases for CAD-CAM complete dentures: A dental technique

In the digital workflow of complete denture fabrication, one solution for producing computer-aided design and computer-aided manufacturing dentures has been to mill the denture teeth and base separately and then bond them together. The correct bonding of the denture teeth and base is important to reproduce the designed occlusion in the definitive prosthesis. A novel technique is described to assist in the accurate positioning of denture teeth on the denture base by constructing auxiliary positioning slots on the denture base and auxiliary positioning posts on the denture teeth. The technique can assist in accurately assembling CAD-CAM milled complete dentures and may shorten chairside time by reducing clinical occlusal adjustment.

Effect of Different Intraoral Scanners on the Accuracy of Bite Registration in Edentulous Maxillary and Mandibular Arches

OBJECTIVES

The objective of this study was to use in vitro models to examine the bite registration accuracy of four different intraoral scanners (IOS) for edentulous maxillary and mandibular arches. The objective was to assess the trueness and precision of the IOS and determine if there were significant differences between them.

METHODS

An Asiga Max UV 3D printer was used to print maxillary and mandibular edentulous models based on the shape of Frasaco models (artificial dental arch models). Four dental implants were placed symmetrically in both models using Straumann BLT RC implants. Digital impressions were taken with Primescan, Trios 3, Trios 4, and Medit i500 intraoral scanners (n = 10 for each IOS). Digital bite registrations were made, and scanning data was exported in STL format. The accuracy of the interarch distance (the distance between the metrological spheres attached to the mandibular and maxillary models) was estimated for each IOS.

RESULTS

The results showed significant differences in trueness and precision between different IOS (p <.05), except Medit i500 and Trios 3 (p >.05). Primescan provided the most accurate results, followed by Medit i500, Trios 3, and Trios 4, respectively.

CONCLUSIONS

within the limitations of this study, the IOS type affects the accuracy of interocclusal bite registration in in vitro design. Only Primescan achieved clinically acceptable accuracy for the interocclusal recording of edentulous arches.

CLINICAL RELEVANCE

The comparison of the accuracy of bite registration between different intraoral scanners will help increase the efficiency of the clinical application of digitalized interarch registration.

Accuracy of Intraoral Scanner for Recording Completely Edentulous Arches-A Systematic Review

Scanning edentulous arches during complete denture fabrication is a crucial step; however, the quality of the resulting digital scan is still questionable. The purpose of this study is to systematically review studies (both clinical and in vitro) and determine whether intraoral scanners have clinically acceptable accuracy when recording completely edentulous arches for the fabrication of removable complete dentures. An electronic search in medical databases like PubMed, Scopus, and Web of Science (WOS), using a combination of relevant keywords, retrieved 334 articles. After full-text evaluation, twelve articles fulfilled the inclusion criteria for this review (eight clinical studies and four in vitro studies). A quality analysis of the included studies was carried out using the QUADAS-2 tool. The accuracy values varied between different intraoral scanners. Different regions of the edentulous arches showed differences in trueness and precision values in both in vitro and clinical studies. Peripheral borders, the inner seal, and poorly traceable structures like the soft palate showed maximum discrepancies. The accuracy of intraoral scanners in recording clear anatomic landmarks like hard tissues with attached mucosa was comparable to conventional edentulous arch impressions. However, higher discrepancies were recorded when digitizing mobile and poorly traceable structures. Intraoral scanners can be used to digitize denture-bearing areas, but the interpretation of the peripheral border and the soft palate should be carefully carried out.

Cast-free fabrication of a digital removable partial denture with a polyetheretherketone framework

Digital workflows for removable partial dentures have enabled new machinable framework materials, including polyetheretherketone (PEEK). In addition, all denture components can be designed and manufactured digitally. Nonetheless, physical casts are still required for assembly of the components. The adoption of a cast-free fabrication procedure may enhance benefits, including a reduced number of procedures, faster processing, and reduced material waste. The purpose of this technical report was to demonstrate a workflow for the fabrication of a removable partial denture with a PEEK framework, milled teeth, and milled flanges, which uses intraoral scanning and no physical casts.

Effect of additional reference objects on accuracy of five intraoral scanners in partially and completely edentulous jaws: An in vitro study

STATEMENT OF PROBLEM

The effect of additional reference objects on the accuracy of different intraoral scanners for partially and completely edentulous patients has not been investigated sufficiently.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of an additional reference object in the form of additional artificial landmarks on the trueness and precision of different intraoral scanners in partially and completely edentulous areas.

MATERIAL AND METHODS

Partially and completely edentulous models with 2 and 4 implants (BLT, RC, Institut Straumann AG), respectively, were used in the study. For the digital scan, scan bodies (CARES Mono Scanbody) were attached, and reference data obtained by using industrial scanners. Ten digital scans of the same model were made with each intraoral scanner: PRIMESCAN, TRIOS 3, TRIOS 4, Carestream 3600, and Medit. Then, additional artificial landmarks were attached, and 10 more intraoral scans were made with each device. Computer-aided design files of the scan bodies were aligned to obtain 3-dimensional surfaces with reference and test scanners. Trueness and precision of distance, angulations, and vertical shift between scan bodies were estimated. The Mann-Whitney Wilcoxon or Student 2-sample t test was applied to estimate statistically significant differences between groups (α=.05).

RESULTS

In the partially edentulous model, distance trueness mean ±standard deviation values ranged from -46.7 ±15.4 μm (TRIOS 3) to 392.1 ±314.3 μm (Medit) in models without additional artificial landmarks. When additional artificial landmarks were applied, trueness of distance mean ±standard deviation values ranged between -35 ±13 μm (TRIOS 4) and 117.7 ±232.3 μm (CARESTREAM). Trueness mean ±standard deviation values of angulation varied from -0.0 ±0.5 degrees (CARESTREAM) to 0.2 ±0.0 degrees (PRIMESCAN) without additional artificial landmarks and from 0.0 ±0.2 degrees (TRIOS 3) to 0.4 ±0.5 degrees (CARESTREAM) with additional artificial landmarks. Vertical shift trueness measurements varied from -108 ±47.1 μm (TRIOS 4) to 107.2 ±103.5 μm (Medit) without additional artificial landmarks and from -15.0 ±45.0 μm (CARESTREAM) to -86.9 ±42.1 μm (TRIOS 4) with additional artificial landmarks. The additional artificial landmark technique improved the trueness of all measured parameters for the 5 tested intraoral scanners. No statistically significant differences were found among models with or without additional artificial landmarks, except for Medit in all parameters and PRIMESCAN in angle measurements (P<.05). The best precision for distance was found with TRIOS 3 and with PRIMESCAN for angulation and vertical shift. Larger deviations were observed in the completely edentulous situation. The effect of additional artificial landmarks was limited when the accuracy parameters of digital scans were considered.

CONCLUSIONS

Scans with and without additional artificial landmarks of partially edentulous conditions scanned by any of the intraoral scanners tested did not influence precision and trueness, except for Medit i500 in the distance and vertical shift parameters and CARESTREAM3600 in vertical shift. Precision and trueness of digital scans of completely edentulous areas were affected, except for Medit i500 for distance, PRIMESCAN and TRIOS 4 for angle, and all systems except TRIOS 4 for vertical shift precision.

Current Status of Digital Complete Dentures Technology

Fabrication of complete dentures (CDs) utilizing computer-aided design and computer-aided manufacturing (CAD/CAM) methods has attracted a lot of attention. The purpose of this paper was to summarize current knowledge about digital CDs and the relevant technology, and to present the application of the new technology in a dental geriatrics case. Initially, some of the challenges regarding digitization of the oral mucosa as a supporting surface of the CDs’ intaglio surface are listed. Next, a brief introduction of the CAD software capabilities regarding CDs is presented. The latest CAM additive and subtractive techniques for CDs are following. Subsequently, the consecutive steps for the construction of a digital CD as part of the prosthodontic treatment of a 90-year-old ambulative female patient are presented. Finally, some considerations about the digital workflow in CD manufacturing are discussed. In conclusion, the new digital technology has clear advantages; however, implementation requires careful planning. The digital workflow is applicable and versatile.

A systematic review of digital removable partial dentures. Part I: Clinical evidence, digital impression, and maxillomandibular relationship record

PURPOSE

This study comprehensively reviewed the current status of digital workflows in fabricating removable partial dentures (RPDs) using evidence from clinical trials and case reports.

STUDY SELECTION

We performed a systematic review of the literature on the materials and fabrication of RPDs using digital technologies published in online databases from 1980 to 2020. We selected eligible articles from the search results, retrieved information on digital RPDs from these, and conducted a qualitative analysis. We report evidence from clinical papers and case reports, digital impression-taking methods, and maxillomandibular relationship (MMR) records.

RESULTS

A case report electronically published in 2019 introduced a clasp-retained RPD fabricated via a full-digital workflow without a gypsum definitive cast. Computer-aided design and computer-aided manufacturing of double-crown-retained RPDs with nonmetal materials were described in some case reports. Intraoral scanners were used to obtain digital impressions and MMR records in the fabrication of digital RPDs, which have potential advantages for reducing the number of clinical appointments and simplifying laboratory procedures. Evidence from clinical trials is scarce; a randomized controlled trial reported higher patient satisfaction with digital clasp-retained RPDs than with conventional RPDs.

CONCLUSIONS

Full-digital RPDs can be fabricated without a gypsum definitive cast. However, the indication for full-digital RPDs is limited to cases with Kennedy Class III/IV partially edentulous arches with several missing teeth. Challenges in digital impression-taking and MMR recording remain to be solved to extend these indications. More evidence from clinical trials is required to evaluate the efficacy and usefulness of digital R PDs.

Digital Immediate Complete Denture for a Patient with Rhabdomyosarcoma: A Clinical Report

Fabricating an immediate complete denture can be very challenging in some clinical situations. This clinical report describes a digital workflow to fabricate a printed maxillary immediate complete denture for a patient with a severely compromised maxilla. Digital data obtained by using an intraoral scanner was utilized to reconstruct the three-dimensional (3D) image of the jaws at the desirable vertical dimension of occlusion. After performing the virtual teeth extraction and alveoloplasty, the denture base and teeth were designed. The resulting data were exported to a 3D printer for denture fabrication and the 3D printed (additively manufactured) denture was successfully inserted immediately after the surgery. After initial healing and confirmation of good retention and function, a new printed denture was fabricated by digitally duplicating the relined denture maintaining the same teeth positions but adjusting the base to a new intraoral scan of the healed ridge.

Using existing interim complete dentures as an aid for an interocclusal record to align edentulous intraoral scans for implant-retained overdentures

This technique describes a workflow to align the maxillary and mandibular edentulous intraoral scans in the computer-aided design and computer-aided manufacturing (CAD-CAM) software program for the fabrication of CAD-CAM implant-retained overdentures. Using the patient's existing and clinically satisfactory interim complete dentures as an aid for the interocclusal record, this technique provides a convenient option for aligning edentulous intraoral scans without the need for an additional clinical appointment, record base, or maxillomandibular tracing device.

Digital maxillomandibular relationship registration for an edentulous maxilla: A dental technique

Recording the maxillomandibular relationship in a patient with an edentulous arch can be challenging in a completely digital workflow. A technique is presented that uses a scan of an existing removable prosthesis to align intraoral scans of the arches.

Integrating intraoral, perioral, and facial scans into the design of digital dentures

Digital technologies offer the opportunity to integrate facial scans into the design of digital dentures and provide a beneficial 3D preview and simulation of the tooth arrangement for both treatment planning and communication. The presented technique describes a procedure of merging and aligning the intraoral scans of edentulous arches, the scans of the perioral area, and the scan of the nose made by using an intraoral scanner, as well as facial scans made by using a mobile phone. Thus, a digital patient can be obtained and used to optimize individual tooth arrangement during the design of the digital denture.