Influence of different scan body design features and intraoral scanners on the congruence between scan body meshes and library files: An in vitro study.

STATEMENT OF PROBLEM: Implant scan bodies (ISBs) present with a variety of features, including diverse design geometries and manufacturing materials. How these features influence the congruence between the clinically obtained mesh file and the software-based library file of the scan body during the alignment stage within the computer-aided design (CAD) software program is unclear. It is also uncertain how these features influence the scanning accuracy of different scanners. PURPOSE: The purpose of this in vitro study was to investigate how various scan body shapes manufactured from different materials influence the scanning accuracy of 6 intraoral scanners (IOSs) and 1 desktop scanner. MATERIAL AND METHODS: A 3-dimensionally (3D) printed cast fitted with 4 different implant analogs and their corresponding scan bodies (Straumann Cares RN Mono; Straumann, MIS V3 SP; MIS, Paltop SP; Paltop and TV70; TRI) was scanned using 6 intraoral scanners (Primescan; Dentsply Sirona, TRIOS 3; 3Shape A/S, TRIOS 5; 3Shape A/S, Medit i-700; Medit, Fussen S6000; Fussen, and Runyes 3DS; Runyes) and 1 desktop scanner (7series; Dental Wings). A metrology mesh comparison software program was used for analysis. Inferences were drawn using a univariate repeated measures 2-way ANOVA. Post hoc analysis was conducted with pairwise Bonferroni tests (α=.05). RESULTS: A significant 2-way interaction was found between scanner model and scan body model, (F [5.518, 49.659]=36.251, P<.001). The mean absolute deviation for the different scanners ranged between 21 µm and 35 µm across all scan bodies, but the model of the scan body influenced the deviation of the scanner. The mean absolute deviation for the different scan bodies ranged from 19 µm to 46 µm across all scanners, but the model of the scanner influenced the deviation of the scan body. CONCLUSIONS: Regarding implant scan body features, a design with a less complex shape and fewer sharp line angles and a design with a cylindrical shape exhibited statistically significantly higher congruence between the clinical mesh and the software library files. Regarding intraoral scanners, Primescan had a statistically significantly lower mean absolute deviation compared with that of the other scanners across all scan bodies tested.

A comprehensive review and update on the current state of computer-assisted rehabilitation in implant dentistry.

AIM: This paper provides a comprehensive review of the established concepts and newer developments related to computer-assisted implant rehabilitation. METHODS: Two independent researchers searched the English literature published to 31st December 2023 in the PubMed/Medline database for primary and secondary research and related publications on computer-assisted implant planning, computer-assisted implant placement and computer-assisted implant restoration. RESULTS: A total of 58,923 papers were identified, 198 relevant papers were read in full text and 110 studies were finally included. Computer-assisted implant rehabilitation was found to result in more precise implant positioning than freehand placement. Advantages include reduced trauma and surgery time; disadvantages include reduced primary implant stability and higher cost. CONCLUSION: Computer-assisted surgery is particularly indicated in cases of critical anatomy, but may encounter limitations in terms of cost, restricted mouth opening, visibility and adjustment of the surgical guides and the need for prior familiarisation with the procedure. Nonetheless, this surgical technique reduces the post-implant placement complication rate.

The current state of computer assisted orthognathic surgery: A narrative review.

OBJECTIVES: Since cone beam computed tomography (CBCT) became available, research in the field of computer assisted orthognathic surgery (CAOS) is constantly on the rising. It is the purpose of the present paper to describe the use of the available digital technology in the workflow of CAOS and to provide insight on the advantages and limitations arising from the use of both hardware and software. STUDY SELECTION, DATA AND SOURCES: Systematic reviews, randomised controlled trials, prospective and retrospective clinical studies, case series and reports were consulted with search terms having been entered into PubMed, Google Scholar and the Cochrane database. RESULTS: There is evidence that supports the use of CAOS, which is based on the lack of time-consuming preparatory steps, more accurate treatment planning and overall, better surgical results. On the contrary, there is also evidence of increased need for training and of higher costs. CONCLUSIONS: The workflow of CAOS involves the acquisition of data which are manipulated to provide the virtual patient, the treatment planning with the appropriate software and the actual preparations for surgery. In case of a non-dynamically guided procedure, it also includes the 3d printing of surgical wafers, osteotomy guides and templates. Even though the native environment for any given surgical treatment planning is three-dimensional, several hurdles seem to impede the universal acceptance of CAOS amongst clinicians. CLINICAL SIGNIFICANCE: CAOS is a much desired yet sparsely employed practice for the correction of congenital, developmental or acquired pathologies in the dentomaxillofacial region. This paper addresses the small details in CAOS workflow towards an effective practice, and describes the advantages and limitations of the software and hardware currently in use.

Influence of different material substrates on the accuracy of 3 intraoral scanners: A single-blinded in vitro study.

PURPOSE: To compare the accuracy of three commercially available intraoral scanners when imaging various dental material substrates. MATERIALS AND METHODS: A maxillary dentate typodont model with 11 different dental material substrates was prepared and scanned using three intraoral scanners (TRIOS 3, 3Shape; CS 3600, Carestream; and Emerald S, Planmeca). The model was further scanned with a laboratory scanner (7series, Dental Wings) for reference. Files were exported in standard tessellation language format and inserted into a metrology 3D mesh software (CloudCompare). RESULTS: In terms of influence of different substrates on IOS trueness, a significant effect on the performance of TRIOS 3 and Emerald S was revealed. Concerning the accuracy of different intraoral scanners when scanning more translucent and reflective materials, pairwise comparisons revealed significant differences among scanners. In terms of complete-arch trueness and precision, pairwise comparisons revealed that TRIOS 3 had significantly higher trueness and precision compared to CS3600 and Emerald S. The complete-arch trueness and precision of CS3600 and Emerald S did not differ significantly. CONCLUSIONS: Dental material substrates influenced the accuracy of all three tested scanners. The full metal crown exhibited significantly lower trueness compared to other substrates across all three scanners. For the high-translucency substrate group, TRIOS 3 exhibited significantly higher trueness compared to CS 3600. Polished and unpolished class II amalgam restorations of similar dimensions did not exhibit significant differences in trueness regardless of intraoral scanner. In terms of complete-arch accuracy, TRIOS 3 had significantly higher trueness and precision compared to CS 3600 and Emerald S. All three scanners exhibited complete-arch average accuracy below 100 µm.

Complete Digital Restoration: Implant-Supported Prosthesis Using Rapid Prototyping and a Model-Free Approach.

This report presents a completely digital workflow utilizing digital intraoral scanning, rapid prototyping techniques, and a monolithic final restoration. A complete fixed prosthesis supported by six implants was used to replace a patient's periodontally compromised mandibular natural dentition. A staged approach was used in which a series of milled and 3D-printed provisional restorations were fabricated to help the patient transition to the dental implant rehabilitation. This cast-free approach allowed for increased patient comfort and greater time efficiency in clinical steps, as each provisional was digitally preplanned and readily available to the clinician before each step.

The direct digital workflow in fixed implant prosthodontics: a narrative review.

BACKGROUND: The purpose of this narrative review was to examine the applicability of IOS procedures regarding single and multiple fixed implant restorations. Clinical outcomes for monolithic zirconia and lithium disilicate restorations produced through a direct digital workflow were reported. METHODS: A MEDLINE (Pubmed) search of the relevant English-language literature spanning from January 1st 2015 until March 31st 2020 was conducted. In vitro studies comparing digital implant impression accuracy by different IOS devices or in vitro studies examining differences in accuracy between digital and conventional impression procedures were included. Also, RCTs, clinical trials and case series on the success and/or survival of monolithic zirconia and lithium disilicate restorations on implants, manufactured completely digitally were included. In vitro and in vivo studies reporting on restorations produced through an indirect digital workflow, case reports and non-English language articles were excluded. The aim was to investigate the accuracy of IOS for single and multiple fixed implant restorations compared to the conventional impression methods and report on the variables that influence it. Finally, this study aimed to report on the survival and success of fixed implant-retained restorations fabricated using the direct digital workflow. RESULTS: For the single and short-span implant sites, IOS accuracy was high and the deviations in the position of the virtual implant fell within the acceptable clinical limits. In the complete edentulous arch with multiple implants, no consensus regarding the superiority of the conventional, splinted, custom tray impression procedure compared to the IOS impression was identified. Moreover, complete-arch IOS impressions were more accurate than conventional, non-splinted, open or close tray impressions. Factors related to scanbody design as well as scanner generation, scanning range and interimplant distance were found to influence complete-arch scanning accuracy. Single implant-retained monolithic restorations exhibited high success and survival rates and minor complications for short to medium follow-up periods. CONCLUSIONS: The vast majority of identified studies were in vitro and this limited their clinical significance. Nevertheless, intraoral scanning exhibited high accuracy both for single and multiple implant restorations. Available literature on single-implant monolithic restorations manufactured through a complete digital workflow shows promising results for a follow-up of 3-5 years.

Use of CBCT and Low-Cost Additive Manufacturing in Implant Surgical Guide Fabrication

The use of dental implants to restore oral form and function has transformed the dental treatment of both partially and fully edentulous patients. With the advent of cone-beam computed tomography (CBCT) imaging technology in 1998 followed by its establishment at the beginning of the new century as the imaging modality of choice in implant treatment, 2-dimensional treatment planning was abruptly supplemented by the much-cherished third dimension. Additive manufacturing, ie, the fabrication of an object by adding material layer by layer, was pioneered in the early 1980s and has become readily available and relatively affordable over the past few years. Although computer-guided planning of treatment is gaining ground in implant therapy, freehand placement of the fixtures remains the standard of care. Time and cost considerations and lack of proper training throughout the steps involved are factors in why clinicians have been reluctant to adopt computer-guided placement of implants. The purpose of this article is to offer guidance to dental clinicians who favor freehand implant placement to facilitate their transition to computer-guided implantology with the use of static surgical guides.

A comparison of accuracy of 3 intraoral scanners: A single-blinded in vitro study.

STATEMENT OF PROBLEM: Measuring both the trueness and precision of an intraoral scanner (IOS) will provide a thorough understanding of its accuracy. PURPOSE: The purpose of this in vitro study was to measure the complete-arch trueness and precision of 3 commercially available intraoral scanners equipped with the latest software version and compare them by using a laboratory scanner as reference. MATERIAL AND METHODS: Nineteen maxillary and 19 mandibular completely dentate stone casts previously acquired from 19 patients by using a polyvinyl siloxane (PVS) dual mix impression and stock trays were scanned with 3 intraoral scanners (TRIOS 3; 3Shape A/S, i500; Medit, and Emerald; Planmeca) using their latest software versions. The same casts were also scanned with a laboratory scanner (E3; 3Shape A/S) that served as the reference scanner. Files were exported in standard tessellation language (STL) format and inserted into a metrology 3D mesh comparison software program (CloudCompare). RESULTS: In terms of trueness, a significant difference was found among the scanners (F (2.37)=239.7, P<.001). Planmeca Emerald had significantly lower trueness values than either the Medit i500 (P<.001) or the 3Shape A/S TRIOS 3 (P<.001). No significant difference in trueness was found between the Medit i500 and the 3Shape A/S TRIOS 3 scanner (P=.365). In terms of precision, a significant difference was found among the scanners (F (2.89)=301.2, P<.001). The 3Shape A/S TRIOS 3 scanner was significantly more precise than the other scanners (P<.001 for both the Medit i500 and Planmeca Emerald). The Planmeca scanner was significantly more precise than the Medit i500 scanner (P<.001). Concerning the ability of the scanners to reproduce the files of the reference scanner without overestimation or underestimation, the Medit i500 produced files that significantly underestimated the reference scanner's files (t (37)=-12.4, P<.001). The other scanners did not significantly either underestimate or overestimate the files of the standard (t (37)=-1.91, P=.062 for the TRIOS 3 and t (37)=1.64, P=.101 for the Planmeca) CONCLUSIONS: With regard to completely dentate arch trueness, the Planmeca Emerald IOS had statistically lower trueness. With regard to complete dentate arch precision, the 3Shape A/S TRIOS 3 IOS was the statistically more precise scanner. With regard to reference scanner file estimation, the Medit i500 IOS produced files that significantly underestimated the reference scanner files. All 3 tested scanners exhibited a completely dentate arch average accuracy below 100 µm in vitro.

Using the surgical guide for impression-free digital bite registration in the edentulous maxilla-a technical note.

Studies reporting on the application of digital bite registration for fully edentulous patients rehabilitated with dental implants are scarce. This article describes a technique for intraoral digital registration of the occlusal vertical dimension in a fully edentulous maxilla to be rehabilitated with a fixed implant prosthesis. Following fully guided placement of six maxillary implants, the surgical stent duplicating the existing upper full denture was securely fixed on two anterior implants and sectioned along the center line of the hard palate. An intraoral scanner was used for the digital impression of the maxilla and dentate mandible. The occlusal vertical dimension was registered on each side using the contralateral part of the surgical guide along with the scanbodies on each side. The procedure allowed for the precise digital mounting of the digitized jaws. The maxilla was restored with a full-arch implant-supported prosthesis.

Rehabilitation of a maxillectomy patient using intraoral scanning impression technology and a computer-aided design/computer-aided manufacturing fabricated obturator prosthesis: A clinical report.

Rehabilitation of a partially dentate postmaxillectomy patient using a novel approach is presented in this report. The patient was referred to our practice by the oral and maxillofacial surgery department of the local general hospital for the evaluation and prosthetic treatment planning. He had undergone biopsy for a lesion located in the right quadrant of his maxilla and was scheduled for a hemimaxillectomy for removal of a squamous cell carcinoma. A surgical obturator was prepared for placement at the time of ablative surgery. Following completion of adjuvant radiotherapy and chemotherapy, a digital intraoral impression of the remaining maxilla and mandible was obtained, and a computer-aided design/computer-aided manufacturing obturator removable partial denture utilizing a selective laser melting -produced metal framework was fabricated and delivered to the patient to restore function and esthetics. The need for conventional impression was eliminated leading to a reduction of necessary appointments and more comfort to the patient.

The use of cone beam computed tomography and three dimensional printing technology in the restoration of a maxillectomy patient using a dental implant retained obturator.

This case report presents an alternative method for fabricating an obturator for patients that develop xerostomia and mild trismus following radiation to the Head and Neck region. Multiple initial impression stages are avoided leading to less irritation to soft tissues and less discomfort to the patient. A 69-year-old male patient was referred to our dental practice by the Maxillofacial Surgery Department of the local General Hospital. The patient had undergone a right maxillectomy for removal of a Squamous Cell Carcinoma 2 weeks prior. Four endosseous dental implants were placed in the remaining upper jaw and 2 implants were inserted into the canine region of his edentulous mandible 3 weeks after ablative surgery. Five months following completion of radiotherapy and chemotherapy, a cone beam computed tomography of the maxilla was obtained, and a three dimensional model was constructed using an appropriate resin. Using the model as the detailed primary cast, a custom acrylic special tray was fabricated for the final impression of the remaining maxilla and the maxillary defect. An implant retained maxillary obturator and an implant retained mandibular overdenture were constructed to restore patient's speech, mastication and deglutition. The method presented here can limit the impression stages needed for construction of a maxillary obturator prosthesis to a single impression procedure advocating a partial digital workflow process. This can be very beneficial to the patient suffering from postradiation side-effects such as trismus, mucositis, and xerostomia.

The influence of interimplant distance and attachment type on the retention characteristics of mandibular overdentures on 2 implants: 6-month fatigue retention values.

This in vitro study evaluated the 6-month fatigue retention provided by 5 paired overdenture attachments placed at 3 different interimplant distances (19, 23, and 29 mm). Mean fatigue retention was calculated for each attachment type and compared with the retention produced by the other attachments tested and the initial retention values published earlier. Interimplant distance was found to play a significant role only in the retention of the Hader bar with red and yellow clips. A significant reduction in retention values was observed for 4 of 5 attachment types.

The influence of interimplant distance and attachment type on the retention characteristics of mandibular overdentures on 2 implants: initial retention values.

PURPOSE: This in vitro study aimed to investigate the influence of (1) the interimplant distance and (2) the type of attachment on the retention of mandibular overdentures on 2 implants. MATERIALS AND METHODS: Three stone casts were fabricated, each with 2 implant analogues embedded at distances of 19, 23, and 29 mm apart. Three different interchangeable mandibular overdenture attachments were secured onto the analogues: Hader bars, ball abutments, and stainless steel keepers for new generation neodymium-iron-boron magnets. In total, 45 groups of paired attachments were tested for initial vertical peak tensile load at the 3 interimplant distances. RESULTS: Interimplant (interclip) distance played a significant role only in the retention produced by the Hader bar/red clip configuration. At 19 and 23 mm, the ball/socket attachments were statistically more retentive than the yellow clips, white clips, and magnets, but not compared to the red clips. At 29 mm, the ball abutments showed statistical superiority compared with all other attachments. Mean clinical intercanine distance for conventional full dentures was 22.88 mm. CONCLUSION: Interimplant distance can affect the initial retention of mandibular overdentures on 2 implants depending on the type of attachment used. For a predetermined interimplant distance, attachment performance varies greatly.

Systematic review of the evidence supporting intra-oral maxillofacial prosthodontic care.

The literature on maxillofacial prosthodontics may be considered to be dominated by articles describing case reports or case series. Prospective, well-controlled clinical trials are scarce owing to the inherent difficulty of performing such trials in patients suffering from oral cancer. The aim of this study was to perform a systematic review of the literature relating to intra-oral maxillofacial prosthodontics based on the principles of evidence-based dentistry. A detailed report of the findings is presented and critically assessed and a discussion of the outcome in respect to the various confounding factors is carried out. Finally, suggestions for future research in the field of maxillofacial prosthodontics are made.