Fabrication of complete denture using 3D printing:a case report / 대한치과보철학회지

Recently with the advance in digital dentistry, the fabrication of dentures using computer-aided design and computer-aided manufacturing (CAD-CAM) is on the rise. The denture designed through a CAD software can be produced in a 3-dimensional manufacturing process. This process includes a subtractive processing method such as milling and an additive processing method such as 3D printing and in which it can be applied efficiently in more complex structures. In this case, complete dentures were fabricated using Stereolithography (SLA)-based 3D printing to shorten the production time and interval of visits in patient with physical disabilities due to cerebral infarction. For definitive impression, the existing interim denture was digitally replicated and used as an individual tray. The definitive impression obtained with polyvinyl siloxane impression material was including information about the inclination and length of the maxillary anterior teeth, vertical dimension, and centric relation. In addition, facial scan data with interim denture was obtained so that it can be used as a reference in determination of the occlusal plane and in arrangement of artificial teeth during laboratory work. Artificial teeth were arranged through a CAD program, and a gingival festooning was performed. The definitive dentures were printed by SLA-based 3D printer using a FDA-approved liquid photocurable resin. The denture showed adequate retention, support, and stability, and results were satisfied functionally and aesthetically.

Perceptions and attitudes of dental hygienists toward radiation safety and protection in the Republic of Korea

To investigate the perceptions and attitudes of dental hygienists toward radiation safety management in Korea. A total of 800 dental hygienists were randomly selected for an anonymous survey, and 203 of them participated. The questionnaire items included the following: sex, career period, type of installed radiographic equipment, recognition of the diagnostic reference level (DRL), participation in radiation safety education, and attitudes toward radiation protection for both patients and dental hygienists. The participants were divided into two groups according to their years of experience (< 10 years versus ≥ 10 years). The difference between the groups was investigated according to frequency distribution. Fisher’s exact test or Pearson’s chi-square (χ2 ) test was used as appropriate. A regression analysis was performed to investigate the impact of wearing a thyroid collar for personnel protection during patient radiation exposure. The types of installed radiographic equipment included panoramic radiography (96.1%), cephalometric radiography (76.9%), intraoral radiography (72.9%), and cone-beam computed tomography (69.5%). Significant differences were observed in the learning pathway for the DRL (Fisher’s exact test, p < 0.05), satisfaction with radiation safety education (Pearson’s χ2 test = 5.3975, Pr = 0.02), and use of personnel radiation monitoring systems (Pearson’s χ 2 test = 18.1233, Pr = 0.000) between the groups. Significant differences were also observed in personnel protection using a thyroid collar and patient protection during panoramic radiography (odds ratio = 14.2). Dental hygienists with more than 10 years of experience were more satisfied with radiation safety education and more interested in radiation monitoring. Considering career experience, customized, continuous, and effective radiation safety management education should be provided.

Complete denture rehabilitation of edentulous patient with severe alveolar bone resorption using mandibular suction denture with closed mouth technique: a clinical report

When it comes to treat patient with loss of vestibule, conventional denture impression have limitation which can cause problems of excessive border extension. Suction denture with closed mouth technique which was introduced to solve this problem, forms negative pressure being sealed denture flanges by mobile mucosa when the patient swallows and chews. Also, it can decrease patient's visiting time by taking impression and gothic arch tracing at once. In this case, considering patient's chief complain which is a loose fit of present lower denture, suction dentures with closed mouth technique was planned.

Fabrication of complete denture using Centric tray and closed mouth technique for edentulous patient / 대한치과보철학회지

Conventional denture impression techniques have limitations for edentulous patients with severe alveolar bone resorption and can cause problems from excessive border extension. Especially when a patient has movable tissue it is difficult to make accurate impression, thus might interrupt stable seating of complete denture. Fabrication of complete denture using closed mouth technique for edentulous patient with severe ridge resorption is thought to provide better stability and retention. In this case, an 86-year-old patient had both edentulous jaws with epulis fissuratum on maxillary anterior ridge and severe mandibular ridge resorption. Thus, tentative vertical dimension was determined by using Centric tray and individual tray attached with gothic arch tracer was fabricated. Complete denture was fabricated using closed mouth technique and the patient was satisfied with better stability and retention of the complete denture.

The accuracy evaluation of digital surgical stents according to supported type / 대한치과보철학회지

PURPOSE: The purpose of this study is to evaluate the accuracy of surgical stent according to the supported type. MATERIALS AND METHODS: 5 sets of dental models which have tooth supported edentulous area and tooth-tissue supported edentulous area were made. Dental model were scanned with model scanner, and CBCT was taken. CT data and model scan data were overlapped using In2Guide software, implant were virtually planned in the software. Surgical stents are fabricated by 3D printing. The implant fixture were installed using the surgical stent, CBCT were retaken. CBCT before surgery and after surgery were overlapped, and the differences (angle difference, coronal difference, apical difference) were evaluated using statistical analysis. RESULTS: In the assessment of the accuracy of surgical guides according to arch type, there are no statistically significant differences between maxilla and mandible. In the case of support type, tooth supported stents showed lower angle difference and length difference than tooth-tissue supported stents, which are statistically significant. CONCLUSION: Arch type does not affect the accuracy of surgical stents. But tooth support stents are more accurate than tooth-tissue support stents in the case of angle and length difference.

The accuracy of a 3D printing surgical guide determined by CBCT and model analysis

PURPOSE: The aim of this clinical study was to assess the accuracy of the implants placed using a universal digital surgical guide. MATERIALS AND METHODS: Among 17 patients, 28 posterior implants were included in this study. The digital image of the soft tissue acquired from cast scan and hard tissue from CBCT have been superimposed and planned the location, length, diameter of the implant fixture. Then digital surgical guides were created using 3D printer. Each of angle deviations, coronal, apical, depth deviations of planned and actually placed implants were calculated using CBCT scans and casts. To compare implant positioning errors by CBCT scans and plaster casts, data were analyzed with independent samples t-test. RESULTS: The results of the implant positioning errors calculated by CBCT and casts were as follows. The means for CBCT analyses were: angle deviation: 4.74 ± 2.06°, coronal deviation: 1.37 ± 0.80 mm, and apical deviation: 1.77 ± 0.86 mm. The means for cast analyses were: angle deviation: 2.43 ± 1.13°, coronal deviation: 0.82 ± 0.44 mm, apical deviation: 1.19 ± 0.46 mm, and depth deviation: 0.03 ± 0.65 mm. There were statistically significant differences between the deviations of CBCT scans and cast. CONCLUSION: The model analysis showed lower deviation value comparing the CBCT analysis. The angle and length deviation value of the universal digital guide stent were accepted clinically.

Restoration of partial removable dental prosthesis after fabricating of surveyed crowns utilizing electronic surveying: a case report

Adoption of CAD/CAM milling in dentistry has allowed production of more analytic and precise prosthesis. Such precision enables definite path of insertion and undercut to be provided in removable partial denture especially when designing a surveyed crown on an abutment tooth. This case is about the production of surveyed crown with proper path of insertion utilizing CAD/CAM electronic surveying method on a patient with edentulous maxilla. Resulting removable partial denture fit well and showed acceptable stability and retention with no clinical problem.

Full mouth rehabilitation of a patient with difficulties in guiding centric relation: A case report / 대한치과보철학회지

The Gothic arch tracing method using a Gothic arch tracer which is one of the centric relation recording methods can reproduce mandibular movement more accurately by describing the path of mandibular curvilinear motion. This case reports that we have satisfactory results by recording reproducible centric relation using a gothic arch tracing method in a patient who has difficulty to induce centric relation by operator due to parafunctional movement.

Complete denture fabricated by Jiro Abe's method for edentulous patient with severe alveolar ridge resorption: a case report / 대한치과보철학회지

Fabrication of complete denture by Jiro Abe's method was introduced that enhance the retention and stability of denture by sealing around the denture border with mucous membrane to make negative pressure at the inner surface of denture base when swallowing or occlusion. In this case, taking impression and fabricating complete denture by the Jiro Abe's method for an edentulous patient with severe mandibular alveolar bone resorption allowed us to obtain clinically enhance stability of denture and improve satisfaction of patient.