Accuracy of impression methods through the comparison of 3D deviation between implant fixtures.

AIM: To compare the accuracy of three impression methods by comparing the distance between the reference points of the implant fixture, especially in curved maxillary anterior teeth. MATERIALS AND METHODS: Implant fixtures were placed in the maxillary central incisor and canine regions. A maxillary master cast was made using a model scanner and 3D printer. Ten impressions were taken from the three experimental groups constructed (group P: pick-up impression coping; group I: scan body with an intraoral scanner; group B: bite impression coping). The distance between the reference points, the angle between the scan bodies, and displacement of the 3D surface area were measured. RESULTS: The distances between the reference points were significantly different between groups I and B in the maxillary incisors, and between group P and the other two groups in the maxillary canines. Group P had the least amount of displacement in both fixtures. Both fixtures showed the highest displacement in group B. Displacement of the 3D surface area in the maxillary incisors showed no significant difference between the groups. There was a significant difference in the maxillary canines between groups P and I. CONCLUSIONS: In the present study, all three implant impression methods showed changes in the position and angle of the fixture compared with the master cast. The highest accuracy was shown by the impression method using the pick-up impression coping, but the impression method using the intraoral scanner also showed clinically acceptable accuracy. It should be noted that errors may occur when taking impressions using a bite impression coping.

User experience of and satisfaction with computer-aided design software when designing dental prostheses: A multicenter survey study.

AIM: The current study aimed to compare the responses and satisfaction reported by users with varying levels of experience when using different types of computer-aided design (CAD) software programs to design crowns. MATERIALS AND METHODS: A questionnaire was used to evaluate user responses to five domains (software visibility, 3Dscanned data preparation, crown design and adjustment, finish line registration, and overall experience) of various CAD software programs. The study included 50 undergraduate dental students (inexperienced group) and 50 dentists or dental technicians from two hospitals (experienced group). The participants used four different CAD software programs (Meshmixer, Exocad, BlueSkyPlan, and Dentbird) to design crowns and recorded the features using the questionnaire. Statistical analyses included one-way and two-way analysis of variance (ANOVA) tests to compare scores and verify the interaction between user response and experience. RESULT: User evaluation scores in the domains of software visibility and 3D-scanned data preparation varied between software programs (P < 0.001), with Exocad being favored by the experienced group. When evaluating crown design and finish line registration, Dentbird and Exocad scored significantly higher than the other software in both groups as they offered automation of the process using deep learning (P < 0.001). Two-way ANOVA showed that prior experience of using CAD significantly affected the users' responses to all queries (P < 0.001). CONCLUSION: User response and satisfaction varied with the type of CAD software used to design dental prostheses, with prior experience of using CAD playing a significant role. Automation of design functions can enhance user satisfaction with the software.

Deep learning and explainable artificial intelligence for investigating dental professionals' satisfaction with CAD software performance.

PURPOSE: This study aimed to examine the satisfaction of dental professionals, including dental students, dentists, and dental technicians, with computer-aided design (CAD) software performance using deep learning (DL) and explainable artificial intelligence (XAI)-based behavioral analysis concepts. MATERIALS AND METHODS: This study involved 436 dental professionals with diverse CAD experiences to assess their satisfaction with various dental CAD software programs. Through exploratory factor analysis, latent factors affecting user satisfaction were extracted from the observed variables. A multilayer perceptron artificial neural network (MLP-ANN) model was developed along with permutation feature importance analysis (PFIA) and the Shapley additive explanation (Shapley) method to gain XAI-based insights into individual factors' significance and contributions. RESULTS: The MLP-ANN model outperformed a standard logistic linear regression model, demonstrating high accuracy (95%), precision (84%), and recall rates (84%) in capturing complex psychological problems related to human attitudes. PFIA revealed that design adjustability was the most important factor impacting dental CAD software users' satisfaction. XAI analysis highlighted the positive impacts of features supporting the finish line and crown design, while the number of design steps and installation time had negative impacts. Notably, finish-line design-related features and the number of design steps emerged as the most significant factors. CONCLUSIONS: This study sheds light on the factors influencing dental professionals' decisions in using and selecting CAD software. This approach can serve as a proof-of-concept for applying DL-XAI-based behavioral analysis in dentistry and medicine, facilitating informed software selection and development.

Assessment of the fit of lithium disilicate crowns at various locations fabricated by three different methods using the triple-scan protocol.

AIM: The present study aimed to evaluate the marginal and internal fit of lithium disilicate crowns at various locations. MATERIALS AND METHODS: A typodont maxillary left first molar was prepared for a lithium disilicate crown, scanned, and a master die fabricated. Three groups were created according to fabrication method (n = 10): conventional impression and press method (group C); scanning of definitive cast and milling method (group D); and intraoral scanning and milling method (group I). Assessment was performed using the triple-scan protocol. At the buccopalatal and mesiodistal sections, the absolute marginal discrepancy (AMD), marginal gap (MG), axial internal gap (AI), and line angle internal gap (LI) were measured. One-way analysis of variance (ANOVA) and post hoc Tukey HSD tests were used for statistical analysis (α = 0.05). RESULTS: AMD values were significantly lower in group C than in groups D and I (P < 0.05). MG values in group C were significantly lower than those in the buccal and distal areas in group D and all areas in group I (P < 0.05). AI values in the buccal and palatal areas in group D were significantly lower than those in the mesial and distal areas in group D and all areas in groups C and I (P < 0.05). LI values were significantly lower in group C than in groups D and I (P < 0.05). CONCLUSION: All three methods were clinically acceptable except for the marginal fit of the intraoral scanning and milling method, which was on the borderline of a clinically acceptable fit. (Int J Comput Dent 2023;26(1): 37-0; doi: 10.3290/j.ijcd.b3818305).

Virtual diagnostics and guided tooth preparation for the minimally invasive rehabilitation of a patient with extensive tooth wear: A validation of a digital workflow.

The recent evolution of digital technologies in dentistry has enabled virtual 3D diagnostic analysis of a dentition before treatment, allowing for virtual, minimally invasive treatment planning. In this report, an extensively worn dentition was 3D virtual analyzed at an increased vertical dimension of occlusion. Virtual waxing (exocad DentalCAD; Exocad) and subsequent analysis of the need for minimally invasive preparations were performed. Areas of each tooth without adequate clearance for the minimal thickness of a definitive restoration (set at 1.5 mm in the software), including the amount of tooth substance to be removed (GOM Inspect; GOM), were visualized in color. A preparation guide was virtually designed according to this diagnostic plan (3-matic; Materialise) and 3D printed (Connex3 Objet260; Stratasys) from resin (VeroMagenta RGD851; Stratasys). The teeth were minimally prepared using the guide, and the amount of preparation was validated by superimposing the scan of the prepared model on the initial scan and comparing it with the diagnostic plan.

Setting the Sagittal Condylar Inclination on a Virtual Articulator Using Intraoral Scan of Protrusive Interocclusal Position and Cone Beam Computed Tomography.

The articulator is a prerequisite device for the analysis of occlusion and prosthodontic treatment, and it is required to simulate patient jaw movements. This article describes the technique to obtain sagittal condylar inclination (SCI) using cone beam computed tomography (CBCT) data and intraoral scan of the protrusive interocclusal position. The SCI can be used on a virtual articulator in a computer-aided design software, and it can assist in the fabrication of prosthesis which is harmonious with the mandibular movement of individual patient.

Combining Conventional Impressions and Intraoral Scans: A Technique for the Treatment of Complete Denture Patients with Flabby Tissue.

The conventional method for impressions of flabby tissue uses modified trays and highly flowable materials, but mucostatic impressions are difficult to achieve due to the viscous and the elastic natures of impression materials. In this report, a technique is presented in which conventional impression and intraoral scanning for a fully edentulous patient with flabby tissue are combined. The definitive impression was obtained by applying appropriate pressure to each tissue area, and the denture can be maintained passively and stable at rest and during function.

A simplified method for evaluating the 3-dimensional cement space of dental prostheses by using a digital scanner.

Evaluating the cement space of various dental prostheses is important because it is related to the stability and retention of the prosthesis. However, a method for evaluating an overall cement space is complex. The purpose of this technique was to simplify the evaluation of prosthesis cement space by using a digital scanner. The form and thickness of the cement space could be simply recognized in any section the clinician or dental researcher wishes. Moreover, the cement space of several dental prostheses for the same abutment could also be precisely evaluated by superimposition. The method can be applied to various prosthodontic treatments.

Piezoelectric Trapezoidal Osteotomy for the Retrieval of a Displaced Dental Implant in the Osteoporotic Mandibular Body.

A female patient in her mid-seventies was referred to our department for the removal of a displaced implant within the right posterior mandible. A trapezoidal window was made using a piezoelectric device. The implant was extracted, and the osteotomized window was replaced without fixation. Caution should be exercised during implant placement in patients with osteoporosis because of the risk of implant displacement. Displaced implants can be easily retrieved by piezoelectric trapezoidal osteotomy.

Comparative Analysis of Screw Loosening With Prefabricated Abutments and Customized CAD/CAM Abutments.

PURPOSE: The aim of this study was to determine the stability of computer-aided design and manufacturing (CAD/CAM) and prefabricated abutment by measuring removal torque before and after cyclic loading. MATERIALS AND METHODS: Three types of fixture and 2 types of abutments were used. Removable torque was measured after cyclic loading for 5000 cycles between 25 and 250 N for each group. The same procedure was performed twice. RESULTS: First, removal torque values (Newton centimeter) were measured for stock versus custom abutments as follows: group 1: 27.17 versus 26.67, group 2: 26.27 versus 26.33, and group 3: 37.33 versus 36.67. Second removal torque values (Newton centimeter) were also measured: group 1: 23 versus 23.5, group 2: 22.5 versus 22.33, and group 3: 32.67 versus 32.5. There was no significant difference between the stock and custom abutments in either the first or second removal torque values and also no significant difference among initial tightening torque, first or second removal torque (P > 0.05). CONCLUSION: With precise control of CAD/CAM abutments, good screw joint stability can be achieved.

Fabricating a tooth- and implant-supported maxillary obturator for a patient after maxillectomy with computer-guided surgery and CAD/CAM technology: A clinical report.

An obturator prosthesis with insufficient retention and support may be improved with implant placement. However, implant surgery in patients after maxillary tumor resection can be complicated because of limited visibility and anatomic complexity. Therefore, computer-guided surgery can be advantageous even for experienced surgeons. In this clinical report, the use of computer-guided surgery is described for implant placement using a bone-supported surgical template for a patient with maxillary defects. The prosthetic procedure was facilitated and simplified by using computer-aided design/computer-aided manufacture (CAD/CAM) technology. Oral function and phonetics were restored using a tooth- and implant-supported obturator prosthesis. No clinical symptoms and no radiographic signs of significant bone loss around the implants were found at a 3-year follow-up. The treatment approach presented here can be a viable option for patients with insufficient remaining zygomatic bone after a hemimaxillectomy.

Osteoblastic and osteoclastic differentiation on SLA and hydrophilic modified SLA titanium surfaces.

PURPOSE: We evaluated the activities of both osteoblastic and osteoclastic differentiation on sandblasted/acid etched (SLA), hydrophilic SLA surfaces (modSLA) and pretreatment titanium (PT). MATERIAL AND METHODS: The osteoblastic differentiation was evaluated by alkaline phosphatase analysis and Alizarin Red S staining, and the expression of bone-related proteins, alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), osteopontin (OPN), and osteocalcin (OCN), was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR). Primary mice monocytes were expanded and differentiated in the presence of macrophage-colony stimulating factor (M-CSF), and osteoclastic differentiation was evaluated by actin ring formation assay and tartrate-resistant acid phosphatase (TRAP) activity assay. Real-time PCR tests were performed to investigate the expression of gene mRNA expression levels in osteoclast cells. RESULT: Differentiation of osteoblasts in the Alizarin Red S test staining and ALP assay was significantly increased in the modSLA surface. The preceding results were supported by the result of RT-PCR for the expression of Runx2, OPN, and OCN. As for osteoclastic activity, differentiated osteoclasts rarely existed on the SLA and modSLA surface with actin ring. The results of real-time PCR and TRAP activity supported the preceding results. CONCLUSION: It may be concluded that the modSLA surface promotes osteogenic effect and prevents osteoclastic differentiation. Promotion of osteoblastic proliferation after a short-term cell culture might be responsible for stimulated bone regeneration implying that early loading may be possible. Also, the anti-osteoclastic effect of the modSLA surface may contribute to maintenance of the marginal bone level of dental implants, implying long-term stability would be provided by this surface technology. The modSLA surface may not only make early loading possible but possibly reduce marginal bone loss during the maintenance phase.

Accurate transfer of soft tissue morphology with interim prosthesis to definitive cast.

With conventional fixed dental prostheses, the interim restoration is a valuable diagnostic tool in the evaluation of esthetics and function. To achieve predictable definitive esthetic results, information about the subgingival and the supragingival contour of a properly designed restoration should be communicated to the dental laboratory technician. The technique described enables the accurate transfer of the soft tissue morphology developed with an interim prosthesis to the definitive cast. This modified definitive cast allows the dental laboratory technician to fabricate a restoration with an emergence profile identical to that of the interim prosthesis.

Prosthetic rehabilitation of a cleidocranial dysplasia patient with vertical maxillofacial deficiency: a clinical report.

Cleidocranial dysplasia (CCD) is a rare congenital disorder characterized by skeletal and dental anomalies. This clinical report describes the prosthodontic approach to treating a CCD patient who presented with decreased facial height and relative mandibular protrusion due to maxillary hypoplasia after orthodontic treatment. Functional and esthetic rehabilitation was achieved using telescopic detachable prostheses in the maxilla and osseointegrated implants and metal-ceramic fixed dental prostheses in the mandible. These treatment approaches precluded the need for orthognathic surgical correction and presented a favorable prognosis during the 5-year observation period.

Revised evaluation objectives of the Korean Dentist Clinical Skill Test: a survey study and focus group interviews

PURPOSE: This study aimed to propose a revision of the evaluation objectives of the Korean Dentist Clinical Skill Test by analyzing the opinions of those involved in the examination after a review of those objectives. METHODS: The clinical skill test objectives were reviewed based on the national-level dental practitioner competencies, dental school educational competencies, and the third dental practitioner job analysis. Current and former examinees were surveyed about their perceptions of the evaluation objectives. The validity of 22 evaluation objectives and overlapping perceptions based on area of specialty were surveyed on a 5-point Likert scale by professors who participated in the clinical skill test and dental school faculty members. Additionally, focus group interviews were conducted with experts on the examination. RESULTS: It was necessary to consider including competency assessments for "emergency rescue skills" and "planning and performing prosthetic treatment." There were no significant differences between current and former examinees in their perceptions of the clinical skill test's objectives. The professors who participated in the examination and dental school faculty members recognized that most of the objectives were valid. However, some responses stated that "oromaxillofacial cranial nerve examination," "temporomandibular disorder palpation test," and "space management for primary and mixed dentition" were unfeasible evaluation objectives and overlapped with dental specialty areas. CONCLUSION: When revising the Korean Dentist Clinical Skill Test's objectives, it is advisable to consider incorporating competency assessments related to "emergency rescue skills" and "planning and performing prosthetic treatment."

Prosthetic rehabilitation of a patient with unilateral dislocated condyle fracture after treatment with a mandibular repositioning splint: a clinical report.

This clinical report describes the use of a mandibular repositioning splint and the subsequent prosthodontic treatment of a unilateral dislocated condyle fracture for a patient whose injury resulted in significant mandibular deviation and malocclusion. The use of a mandibular repositioning splint considerably reduced the mandibular deviation, and a stable mandibular position was maintained with the definitive prosthesis.

The effects of mouthguards on the athletic ability of professional golfers.

The purpose of this study was to determine the effect of stabilization splints and mouthguards on the athletic ability of professional golfers. For this study, eight professional golfers with a mean age of 20.5 were selected. These participants performed four trials of 10 driver swings and 10 putts with or without a stabilization splint (control group) or mouthguard. For the 4th trial, the splints were adjusted using a simple blind test so that the participants were unaware of the unilateral molar contact. The drive distance, club head speed, initial ball speed, and putting accuracy were compared and analyzed before and after the application of equal bilateral molar occlusion. When the bilateral molar occlusion was applied using a mouthguard or stabilization splint, the club head speed and driving distance in the presence of the oral appliances were significantly increased compared with those without the presence of either appliance (P < 0.05). Alternatively, the initial ball speed and putting accuracy in the presence of these appliances were increased compared with those without the presence of an appliance; however, this effect was not statistically significant. When the mouthguards or stabilization splints were adjusted to result in unilateral molar occlusion, the club head speed and driving distance in the presence of the appliances were significantly decreased compared with those that were obtained without these appliances (P < 0.05). The initial ball speed and the putting accuracy were not affected by the use of the appliances. No difference was observed in the effectiveness of the stabilization splint and mouthguard when bilateral molar occlusion was performed. The occlusion stability that results from stabilization splints and mouthguards is thought to increase the club head speed and driving distance in professional golf players.

Clinical outcome of narrow diameter dental implants: a 3-year retrospective study.

BACKGROUND: This study aimed to analyze the clinical outcome and complications of narrow-diameter dental implants (NDIs) (diameter ≤3.5 mm). METHODS: The 274 NDIs that met the selection criteria from 2013 to 2018 were included in the retrospective study, and the survival rates (SVR) were compared. Mechanical complications included screw loosening and fractures of the implant components, such as the implant fixture, abutment, and prosthesis. In addition, marginal bone loss (MBL) was measured immediately after surgery and 1 year after loading. RESULTS: The 3-year cumulative SVR was 92.4%. Nineteen fixtures failed during the follow-up. The failure rate was significantly higher (OR=4.573, p<0.05) in smokers and was significantly higher in osteoporosis patients (OR=3.420, p<0.05). The vertical and horizontal values of MBL were 0.33±0.32 mm and 0.18±0.17 mm, respectively. Mechanical complications included screw loosening (5.5%) and porcelain fracture (2.2%), but no fractures of the fixture or components were observed. The choice of titanium and zirconium (TiZr) alloy implant was significantly more frequent in the posterior region. Bone graft was significantly more frequently done in the anterior region. CONCLUSIONS: According to the high SVR and stability of NDIs, the findings of the study suggest that NDIs may be a replacement for regular diameter dental implants (RDIs) and the use of TiZr alloy could extend the indication of NDIs. In the esthetic area, contour augmentation may be a reason for increasing the frequency of bone grafts.

The prosthetic rehabilitation of a panfacial fracture patient after reduction: a clinical report.

Panfacial fractures involve trauma to the lower, middle, and upper facial bones and often require a team approach for management. Early and complete restoration of preinjury facial contours and function should be the goal of the oral and maxillofacial surgeon and the prosthodontist. When the intraoral landmarks are lost, overall facial anatomic landmarks can be used to restore the oral cavity. A patient with complex clinical panfacial fractures, including a vertically and horizontally malpositioned native alveolar bone and severe facial asymmetry, is presented. A functional and esthetic rehabilitation was successfully accomplished by using a partial removable dental prosthesis retained with telescopic crowns and magnetic attachments in the maxilla and osseointegrated implants to support a definitive dental prosthesis in the mandible.

The effects of enamel matrix derivative on the proliferation and differentiation of human mesenchymal stem cells.

PURPOSE: This study was designed to investigate the effect of enamel derivative matrix (EMD) on the proliferation, mineralization, and differentiation of human mesenchymal stem cells (hMSCs). MATERIAL AND METHODS: For the proliferation assay, water-soluble tetrazolium salt-8 tests were carried out after culturing for 24 and 48 h. For the evaluation of mineralization, Alizarin red S (ARS) tests were performed after 21 days of culturing in an osteogenic medium. In order to investigate some of the bone-related proteins, namely type I collagen (Col I A2), bone sialoprotein (BSP), and bone gamma-carboxyglutamate (Gla) protein (BGLAP, osteocalcin), real-time polymerase chain reaction (RT-PCR) tests were carried out after 2, 3, and 4 weeks of culturing, respectively. RESULTS: The activity of proliferation and mineralization increased significantly depending on the concentration of EMD (P<0.05). In the control group, the expression of Col I A2 decreased, but EMD enhanced its expression over time and was correlated to the concentration. The amount of expression of BSP in this group increased over time, but EMD strikingly suppressed its expression in the fourth week. As well, the amount of expression of BGLAP increased as the culture duration lengthened in the control group. However, the expression of BGLAP was suppressed in the experimental group with EMD. CONCLUSION: Within the limits of this study, EMD enhanced the proliferation of hMSCs. After evaluation with ARS staining, EMD seemed to enhance mineralization, and the RT-PCR test revealed that EMD promoted early-stage osteoblast differentiation by enhancing Col I A2 expression, but exerted an inhibitory effect on the mineralization by lowering the gene expression of BSP and BGLAP. Mineralized nodules formed with EMD may be composed of substances other than normal bone. Because most of the organic matrix of bone is type I collagen, which acts as the mineralization site, bone or bone-like mineralized mass might have been formed in spite of the different components of the non-collagenous proteins.