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Trueness and precision of an intraoral scanner in digitally copying complete dentures

Gavras, Joanna Nicolette; Abdullah, Johari Yap; Choi, Mijin; Turkyilmaz, Ilser
Background/purpose: The ability to save a digital copy of a fabricated denture is poignant for large dental institutions. The purpose of this study was to evaluate the trueness and precision of an intraoral scanner (IOS) in its ability to digitally duplicate a complete denture (CD) and evaluate the possible effects of file resolution reduction on different exported media types. Materials and methods: A desktop scanner was used to scan a complete mandibular denture and utilized as the control file. An IOS was used to scan the same denture and exported into both standard triangular language (STL) and polygon (PLY) file types and stored for additional analysis. The different file types at original resolution were compared to the desktop scan (DS100) to evaluate the accuracy of the IOS. Then the STL (Groups S100, S75, S50, S25) and PLY (Groups P100, P75, P50, P25) files were reduced in their resolutions to evaluate any statistical discrepancies in the volumetric analysis of the scan using the Hausdorff distance (HD) and dice similarity coefficient (DSC). Results: When compared to the desktop scan (14888.40 mm3), the measured volume of the exported STL (Group S100: 15236.45 ± 114.67 mm3) and PLY (Group P100: 15231.71 ± 97.12 mm3) files from the IOS produced a similarity of 98.34% and 98.39% respectively. The similarity of the IOS files at different resolutions ranged from 99.99% to 99.96%. Conclusion: We conclude that the IOS used in this study demonstrates very high trueness and precision when digitally duplicating complete dentures.
ISSN: 1991-7902
CID: 5425912

In vitro comparison of physical characteristics of milled versus printed zirconia discs

Giugliano, Thomas S.; Zhang, Yu; Janal, Malvin N.; Lim, Chek Hai; Smith, Ruby M.; Choi, Mijin
Purpose: The purpose of this study was to compare the dimensional accuracy, translucency, and biaxial flexural strength of milled zirconia (MZ) versus 3D-printed zirconia (PZ) discs. Materials & Methods: A circular disc measuring 14.0 mm in diameter and 1.20 mm in thickness was designed using computer-aided design (CAD) software. The resulting standard tessellation language (STL) file was used both as a control and to fabricate 36 zirconia (3Y-TZP) disc specimens (n = 36): 18 were milled (group MZ) and 18 were 3D-printed (group PZ). The diameter and thickness of each disc were measured using a digital caliper. Translucency was evaluated using a calibrated dental colorimeter. The flexural strength was determined using the piston-on-three-ball biaxial flexure test. All measurements were done by one blinded examiner. The statistical significance level was set to α = 0.05. Results: The MZ discs had significantly more accurate dimensions than the PZ discs in both diameter and thickness when compared to the control CAD software-designed disc. The MZ discs exhibited significantly higher translucency (translucency parameter (TP) = 16.95 ±0.36 vs. 9.24 ±1.98) and biaxial flexural strength (996.16 ±137.37 MPa vs. 845.75 ±266.16 MPa) than the PZ discs. Finally, MZ possessed a significantly higher Weibull modulus relative to PZ. Conclusions: The results showed that the milled specimens achieved better dimensional accuracy and were more translucent, stronger, and less prone to failure than printed specimens.
ISSN: 1059-941x
CID: 5616382

Digital Analysis of the Dimensional Change Of an Irreversible Hydrocolloid Impression Material (Alginate) with Varying Storage Times

Ibrahem, Fatemah; Giugliano, Thomas; Ruff, Ryan Richard; Choi, Mijin
AIM/UNASSIGNED:The aim of this study was to digitally measure the dimensional changes in an irreversible hydrocolloid impression material (alginate) resulting from varying storage times under optimal storage conditions. MATERIALS AND METHODS/UNASSIGNED:A single type V dental stone control cast was used to make 25 alginate impressions using perforated stock trays. The impressions were randomly assigned into five groups of five samples each (n=5 per group) with varying storage times: Group 1, poured at 15 minutes; Group 2, poured at one hour; Group 3, poured at 24 hours (one day); Group 4, poured at 72 hours (three days); Group 5, poured at 168 hours (seven days). All impressions were stored in sealed Ziploc® plastic bags with a wet paper towel (100% relative humidity) at room temperature and stored according to the assigned group storage times. All impressions were poured in type V dental stone according to the manufacturer's instructions. The casts were scanned with a digital 3D desktop scanner and saved as electronic stereolithography (.stl) files. Each .stl file of the scanned casts were superimposed on the .stl file of the control cast using Geomagic® Control X™ software. Three preselected fixed comparison measuring points (CMP) on each cast were compared to the control cast. Point one (CMP1) was on the midfacial surface of central incisor. Point two (CMP2) and point three (CMP3) were on the mesiobuccal proximal marginal ridge areas of third molars. The discrepancies between the files at each point were analysed with colour maps, and quantified (Table 1). The tolerance was set at ±10μm. CMP scores were analysed using one-way analysis of variance (ANOVA) and Kruskal-Wallis (K-W) non-parametric H tests. RESULTS/UNASSIGNED:= 3.62, p = 0.46). CONCLUSIONS/UNASSIGNED:Under optimal storage conditions, there were no significant dimensional changes in casts poured from alginate up to seven days.
PMID: 36533371
ISSN: 2050-1684
CID: 5394532

In vitro shear bond strength of 2 resin cements to zirconia and lithium disilicate: An in vitro study

Woo, Evelyn Seungmin; Goldstein, Gary; Choi, Mijin; Bromage, Timothy G
STATEMENT OF PROBLEM/BACKGROUND:) or glazed material will affect the shear bond strength (SBS) of different resin cements. PURPOSE/OBJECTIVE: ceramic, both glazed and nonglazed, and a lithium disilicate (LDS) ceramic. MATERIAL AND METHODS/METHODS:plates at the appropriate layer, and 2 cylinders were luted to each LDS plate. The specimens were stored in a moist environment for 24 hours at 37 °C. The SBS test was performed with a universal testing machine. Visual inspections of the debonded surfaces were compared under magnification. The data were analyzed with a 2-way ANOVA and a subsequent Student t test (α=0.05). RESULTS:. CONCLUSIONS: cubic and tetragonal layers, the DPRC had higher bond strengths to the nonglazed surfaces.
PMID: 32354421
ISSN: 1097-6841
CID: 4412772

Management of Amelogenesis Imperfecta in Adolescent Patients: Clinical Report

Ortiz, Liliana; Pereira, Ann Marie; Jahangiri, Leila; Choi, Mijin
The oral rehabilitation of adolescent patients with amelogenesis imperfecta (AI) is complex due to the presence of mixed dentition with altered eruption sequence. In this manuscript, the interdisciplinary treatment approach for adolescent patients with AI is discussed. The types and timing of treatments at various stages of growth are described through a literature review on this topic. AI is an inherited condition that disturbs the development of the enamel structure. Because of the presence of mixed dentition, definitive treatment options often have to be delayed until eruption of permanent dentition is complete, requiring careful treatment coordination and proper sequencing between different dental disciplines starting at a young age. Adolescent patients require prosthodontic treatment design that can be adapted to the changes in arch shapes, sizes, interarch relationship, and esthetic needs. AI patients are often challenged with both excessive and limited restorative spaces within the same arch due to the abnormal growth patterns, enamel structure, tooth size, and tooth shape. Therefore, careful determination of the required restorative space is critical to ensure optimal prognosis. This clinical report discusses treatment recommendations, timing of various treatment modalities, and involvement of appropriate interdisciplinary teams for managing adolescent patients. This article is protected by copyright. All rights reserved.
PMID: 31054208
ISSN: 1532-849x
CID: 3915792

Defining centric relation

Wiens, Jonathan P; Goldstein, Gary R; Andrawis, Mark; Choi, Mijin; Priebe, Jennifer W
STATEMENT OF PROBLEM/BACKGROUND:Multiple definitions of centric relation (CR) have evolved over time that may have created confusion or impeded understanding. A recent attempt to achieve a singular definition by surveying the members of the Academy of Prosthodontics (AP) did not achieve majority consensus. PURPOSE/OBJECTIVE:The purpose of this study was to identify those aspects or attributes within the existing definitions of CR in which there was agreement or disagreement among the members of the AP. MATERIAL AND METHODS/METHODS:After pretesting and institutional review board approval, a second survey of the AP membership was performed using both email and postal mail survey methods of contact. The CR Attributes Survey separated and stratified the previous definitions of CR into 5 domains: spatial relationship, condylar position, articular disks, mandibular movement, and recording. Each domain attribute was evaluated by agree-uncertain-disagree assessments. Also recorded were demographics, perception of scientific evidence, and open comments. RESULTS:Of the total 146 fellows, 100 completed the survey for an overall response rate of 68.5%. The query completion rate ranged from 96% to 98%. The CR Attributes Survey revealed those components within each domain in which there was strong agreement, disagreement, or uncertainty. The survey assessment of those queries with a moderate to strong agreement were that CR is a "spatial relationship" that is (1) a clinically determined relationship of the mandible to the maxilla, (2) a repeatable position, (3) is independent of tooth contact, and (4) is a physiologic position. Relative to "disks," the condyles articulate with the thinnest avascular intermediate zone of their respective disks; however, there is a lack of sufficient evidence to determine the position of the disks and the condyles. Relative to "mandibular movement," CR is (1) a starting point for vertical, lateral, or protrusive movements, (2) is where the individual can make to and from lateral movements, and (3) is restricted to pure rotary movement about a transverse horizontal axis. Relative to "recording CR" (1) it can be determined in patients without pain or derangement of the temporomandibular joints (TMJs), (2) but may not be recordable in the presence of dysfunction of the masticatory system, or (3) due to the neuromuscular influence or proprioception from the dentition, (4) is a clinical useful repeatable reference position for mounting casts, or (5) for developing a functional treatment occlusion, (6) at an established vertical dimension, and (7) may vary slightly by recording method. CONCLUSIONS:The CR Attributes Survey revealed a majority agreement or consensus for various CR attributes that should be considered for defining the term 'centric relation.' In contrast, those CR attributes with a plurality agreement, disagreement, or uncertainty outcomes should be considered for exclusion. The evaluated weakness of these latter attributes indicates the need for further research and reassessment.
PMID: 29526300
ISSN: 1097-6841
CID: 3040702

A survey to determine agreement regarding the definition of centric relation

Goldstein, Gary; Andrawis, Mark; Choi, Mijin; Wiens, Jonathan; Janal, Malvin N
STATEMENT OF PROBLEM: The definition of centric relation (CR) has been both controversial and divisive, with little consensus. PURPOSE: The purpose of this study was to determine whether agreement can be reached on a definition for CR among the Fellows of the Academy of Prosthodontics, the organization that writes the Glossary of Prosthodontic Terms. MATERIAL AND METHODS: A survey of the Fellows of the Academy of Prosthodontics was conducted at the organization's annual business meeting. RESULTS: Of the 83 eligible Fellows in attendance, 72 responded to the survey, a response rate of 86%. Of those, the 5 responders who did not indicate a preferred definition and the 2 that chose 2 definitions were censored, yielding an analyzable sample of 65 for the definitions. The most common definition received 19 votes, the next 16, and the third 13, with the other 6 definitions receiving from 2 to 5 votes. Some of the variability in definition depended on the era of training. CONCLUSIONS: Disagreement and confusion continues regarding the definition of centric relation. Some of this disagreement can be explained by training era.
PMID: 27765398
ISSN: 1097-6841
CID: 2280262

Mandibular fibular graft reconstruction with CAD/CAM technology: A clinical report and literature review

Mehra, Mamta; Somohano, Tanya; Choi, Mijin
This clinical report describes the treatment of a partially dentate patient who presented with dental implants placed in a reconstructed fibula graft in the mandible. A complete mouth rehabilitation with a maxillary complete denture and a mandibular implant-supported fixed complete denture was fabricated with computer-aided design and computer-aided machining technology.
PMID: 26372630
ISSN: 1097-6841
CID: 1779532

Restoration Of The Compromised Occlusion: Case Reports Using A Two Phased Approach

Chapter by: MacGregor, Kimberly J; Boonsiriphant, Piriya; Lopes, Ana S; Hirsch, Joel A; Choi, Mijin
in: Clinical & Educational Scholarship Showcase by
[New York NY : NYU College of Dentistry. NYU Academy of Distinguished Educators], 2015
pp. 27-27
ISBN: n/a
CID: 1873322

leInterventions for missing teeth: Removable prostheses for the edentulous mandible [Review]

Jahangiri, Leila; Choi, Mijin; Moghadam, Marjan; Jawad, Sarra
ISSN: 1361-6137
CID: 2113342