Comparison of internal adaptation of removable partial denture metal frameworks made by lost wax technique and printing technique of pattern using CAD / 대한치과보철학회지

Lost wax technique of casting wax patterns has been used principally to make metal frameworks of removable partial dentures. Since the development of digital technology and CAD, metal frameworks can be built through digital surveying and framework designing. Many cases proved that resin patterns made by CAD printing method were well adapted to internal oral structure and final metal frameworks also showed good internal adaptation as well. The metal frameworks of a removable partial denture were made by both lost wax technique and CAD technique and were applied to a patient with severe alveolar bone loss. Using CAD data and fit checker, internal adaptation of both metal frameworks were evaluated by comparing the gap between surveyed crown and its structure. This study is to prove that metal frameworks by both techniques showed adaptation that can be applied in clinical field.

Oral rehabilitation that transit from optimized provisional through continuous re-evaluation to definitive prosthesis using CAD/CAM system: A case report / 대한치과보철학회지

Prosthetic decision-making is complex because of various factors, and involves a combination of the individual dentist's interpretation of the objective clinical data and his or her interaction with the patient. Increasing therapeutic options and emerging outcome data demand the constant re-evaluation of our decision-making process. In this case, fixed prosthetic restorations were selected as a treatment method to reconstruct the occlusal plane of a patient with disharmonious occlusal plane. And the occlusal plane was re-established by establishing a treatment plan through diagnostic wax-up. Provisional restorations obtained by continuous re-evaluation for a sufficient period of time was replicated to definitive restorations using CAD/CAM technology. The results were satisfactory when they were observed through clinical follow-up for 3 months after the end of treatment.

Effect of coloring agent on the color of zirconia / 대한치과보철학회지

PURPOSE: The aim of this study was to evaluate the effect of two types of coloring agents and the number of application on the color of zirconia. MATERIALS AND METHODS: Monolithic zirconia specimens (15.7 mm × 15.7 mm × 2.0 mm) (n = 33) was prepared and divided into 11 groups. Each experimental group was coded as a1-a5, w1-w5 according to the type of coloring agent and number of application. Specimens with no coloring agent applied were set as control group. The color difference of specimen was measured by using double-beam spectrophotometer, and calculated color difference (ΔE*(ab)), translucency parameter (TP). All data was analyzed with two-way ANOVA, multiple comparison Schéffe test, Pearson correlation and linear regression analysis. RESULTS: As the number of application increased, values of CIE L* was decreased, but values of CIE b* was increased in both coloring agents. However, there was no significant difference on values of translucency parameter. The color difference range of each group was 0.87 ΔE*(ab) to 9.43 ΔE*(ab). CONCLUSION: In this study, type of coloring agent and the number of application did not affect the color difference of zirconia.

Full-mouth rehabilitation of skeletal anterior open bite with severely decayed dentition: A case report / 대한치과보철학회지

The open bite malocclusion is a common clinical entity and has multifactorial causes. Development of effective treatment plan and management is dependent on proper diagnosis. The skeletal open bite patient requires a coordinated orthodontic and orthognathic surgical approach to achieve stable occlusion, acceptable esthetics, and improved function. But in case of open bite with severely decayed dentition, restoration in the entire dentition is necessary. Using the facial analysis and diagnostic wax-up, the most effective treatment was prosthetic rehabilitation. The provisional restorations were fabricated to satisfy esthetic and functional requirements, which result in the uniformly distributed occlusal force, anterior and canine guidance. The inter-arch relationship, labio-dental harmony, and the soft tissue aspect, which is important to estimate the longevity were evaluated. Definitive restorations of monolithic zirconia were made by replicating provisional restorations by using the latest CAD/CAM technology. They were delivered to the patient and clinical follow-up observation was satisfactory.

The esthetic prosthodontic treatments in maxillary anterior area, considering the gingival margin / 대한치과보철학회지

To enhance the esthetic appearance, the maxillary anterior area is important. It is possible to improve the esthetic appearance through the treatment of maxillary anterior area, which includes altering the color, form, and arrangement of teeth. When planning these treatments, clinicians should individualize personal demands, by using the information obtained from facial, dento-labial, dental, and gingival analysis. It is essential to properly prepare the gingival structure, which includes the height of gingival margin, the location of zenith, reconstruction of the interdental papillae, emergence profile, and symmetry. Clinicians often face unfavorable condition of the gingiva and the edentulous ridge, and appropriate management of the gingival structure is needed. In this case report, the patients were treated to improve the gingival conditions surrounding maxillary anterior teeth. By using conservative treatment without surgical intervention, such as application of pink porcelain, subgingival contour modelling and modification of pontic base, satisfactory esthetic results were gained.

Prosthetic restoration of a partially edentulous patient using double crowns: a clinical report / 대한치과보철학회지

In removable dental prostheses, it is important to minimize impairment of residual tissue caused by wearing dentures. There are two factors that harm residual tissue. The first is functional load bearing of remaining teeth and alveolar ridges and the second is the effect of poor oral hygiene. Double crown retained removable dental prostheses provide rigid support, and it may reduce impairment caused by load bearing of alveolar ridges. Also, dental plaque and oral deposits, which are attached to outer crowns and dentures, can be easily managed extra-orally. In addition, it is beneficial to the health of the marginal gingiva because inner crowns have easy access for oral hygiene. In this case, double crown retained removable dental prostheses were used for the partially edentulous patient with severe residual alveolar bone resorption and poor oral hygiene, and the result was clinically satisfactory in terms of functional, esthetical, and oral hygiene aspects.

Reconstruction of implant prostheses under infraocclusion: a case report / 대한치과보철학회지

Implant has been an effective treatment option for the patients with oligodontia. However, it still remains unclear when the implant should be placed. Skeletal growth that can appear even after the growth period can lead to infraocclusion of the implant which can cause functional or esthetic complications. In order to minimize these problems, definitive restorations should be placed after the functional and esthetic rehabilitation is achieved through the use of provisional restorations. Definitive restorations made with monolithic zirconia were created by replicating provisional restorations by using the latest CAD/CAM technology. These definitive restorations were delivered to the patient and clinical observation after the treatment showed satisfactory result.

Cell attachment and proliferation of bone marrow-derived osteoblast on zirconia of various surface treatment

PURPOSE: This study was performed to characterize the effects of zirconia coated with calcium phosphate and hydroxyapatite compared to smooth zirconia after bone marrow-derived osteoblast culture. MATERIALS AND METHODS: Bone marrow-derived osteoblasts were cultured on (1) smooth zirconia, (2) zirconia coated with calcium phosphate (CaP), and (3) zirconia coated with hydroxyapatite (HA). The tetrazolium-based colorimetric assay (MTT test) was used for cell proliferation evaluation. Scanning electron microscopy (SEM) and alkaline phosphatase (ALP) activity was measured to evaluate the cellular morphology and differentiation rate. X-ray photoelectron spectroscopy (XPS) was employed for the analysis of surface chemistry. The genetic expression of the osteoblasts and dissolution behavior of the coatings were observed. Assessment of the significance level of the differences between the groups was done with analysis of variance (ANOVA). RESULTS: From the MTT assay, no significant difference between smooth and surface coated zirconia was found (P>.05). From the SEM image, cells on all three groups of discs were sporadically triangular or spread out in shape with formation of filopodia. From the ALP activity assay, the optical density of osteoblasts on smooth zirconia discs was higher than that on surface treated zirconia discs (P>.05). Most of the genes related to cell adhesion showed similar expression level between smooth and surface treated zirconia. The dissolution rate was higher with CaP than HA coating. CONCLUSION: The attachment and growth behavior of bone-marrow-derived osteoblasts cultured on smooth surface coated zirconia showed comparable results. However, the HA coating showed more time-dependent stability compared to the CaP coating.

Retentive bond strength of fiber-reinforced composite posts cemented with different surface treatments / 대한치과보철학회지

PURPOSE: This study will evaluate the effectiveness of various pretreatments when fiber-reinforced composite (FRC) post is bonded to endodontically treated tooth with resin cement. MATERIALS AND METHODS: Canal shaping of FRC post (DT Light post, Size 3, Bisco Inc., Schaumburg, IL, USA) was performed on endodontically treated premolars at 1.5 cm from CEJ. Samples were divided into 6 groups of surface treatment after conventional washing and drying to the canal. Total of 24 FRC posts were randomly divided into 6 groups of surface treatment as follows: Group C: control - no surface treatment, Group A: airborne-particle abrasion (Cojet sand, 3M ESPE), Group S: silanization (Bis-silane, Bisco Inc.), Group M: universal primer (Monobond-plus primer, Ivoclar Vivadent Inc.), Group AS: silanization after airborne-particle abrasion, Group AM: universal primer treatment after airborne-particle abrasion. Pretreated fiber posts were cemented with resin-based luting material and photo-polymerized and cut to the thickness of 1 mm. Push-out test using a universal testing machine was performed. Bonding failure strength of post dislodgement was measured and the type of bonding failure was classified. Data were analyzed with Kruskal-Wallis test and multiple comparison groups were performed using Tukey HSD value of rank test (alpha=0.05). RESULTS: Group AS showed significantly highest bonding strength. Group S, group AM, group A, and group M showed lower bonding strength in order. The control group showed the lowest bonding strength. CONCLUSION: Surface treatment with silane showed to be the most effective of the surface pretreatment methods for cementation of FRC post. Surface treatment with universal primer showed no significant difference compared with no surface treatment group as for bonding strength.

Full-mouth rehabilitation of a patient with reduced occlusal vertical dimension due to severe wear: a clinical report / 대한치과보철학회지

The loss of posterior support may cause attrition of anterior teeth, and loss of occlusal vertical dimension (OVD). The collapse of the posterior support will eventually cause the pathologic change of the TMJ and masticatory muscles, unesthetic facial appearance and decreased masticatory function. Patients with destroyed dentition need extensive prosthetic treatments. Proper diagnosis and treatment planning are necessary for the stability of the neuromuscular system and the TMJ, and esthetic and functional definitive restorations. In this case, 63 year-old male presented with decreased masticatory force and esthetic problems due to pathologic destruction of teeth structure on entire dentition. Based on assessment of OVD including intraoral findings, radiographic examination and diagnostic cast, full-mouth rehabilitation with increase of OVD was planned using fixed partial denture and removable partial denture. Diagnostic wax-up was done after 4 mm increase of OVD determined by assessment of OVD. The OVD was maintained with the overlay type removable interim prostheses for 12 weeks to ascertain his comfort and adaptation to the new OVD. After the adaptation period, second interim prostheses with tooth preparation maintaining the established OVD was delivered. After 4 weeks, final prostheses were fabricated and delivered. After 7 month follow-up period, occlusal stability is maintained. Through this procedure, satisfactory outcomes were achieved both in functional and esthetic aspects.

Full-mouth rehabilitation with pressed ceramic technique using provisional restorations / 대한치과보철학회지

With the introduction of dental implants, restoration of missing teeth with conventional fixed or removable partial dentures is being replaced with implants. Especially, with young patients, not only longevity but also esthetic factors need to be considered. Implant restorations provide long-term success functionally but, esthetic complications such as, marginal exposure due to gingival recession, loss of the papilla and dark color of metal abutments may occur. Recently, zirconia restorations with CAD/CAM technology provide functional, biocompatible and esthetic restorations possible. All-ceramic restorations using the pressed ceramic technique show better fracture toughness values than those of the conventional porcelain veneering technique. Pressed ceramic technique creates the veneer design in wax and the lost wax technique is used to create the restoration. The final contour of the restoration may be controlled during wax-up. A 22-year old female patient was restored with dental implants and zirconia restorations using the pressed ceramic technique presenting short-term but optimistic prognosis.

Analysis of occlusal contact and guidance pattern during maximal intercuspal position and protrusive movement / 대한치과보철학회지

PURPOSE: The importance of occlusal contacts of the natural dentition for durability of teeth, mandibular stabilization, and restorative dentistry is well known. The purpose of this study is to analyze the occlusal contact and guidance pattern of Koreans by evaluating the static occlusion on maximal intercuspal position and measuring dynamic occlusion during straight protrusion. MATERIALS AND METHODS: The occlusal contacts at maximal interincisal position and the occlusal guidance pattern during straight protrusion of 29 subjects were recorded with shimstock foil (Whaledent, Langenau, Germany), T-Scan III (Tekscan Inc., Boston, MA, USA), polyvinylsiloxane registration material (Genie Bite, Sultan Healthcare, Hackensack, NJ, USA) and compared. Occlusal registration procedures were repeated 3 times. The position was fixed to an upright position and the head position was fixed with the Frankfurt horizontal plane paralleling the horizontal plane. Fisher's Exact Test (R-General Public License, ver. 2.14.1) and Pearson's Test were used to assess the significance level of the differences between the experimental groups (alpha=.05). RESULTS: When using shimstock foil, T-Scan III system, and polyvinylsiloxane registration material, most of the patients showed contact on anterior, premolar, and molar teeth during maximal intercuspal position. Approximately 51% of maximal intercuspal position showed anterior contact using shimstock foil. When examining the protrusive movement using shimstock foil and T-Scan III system, guidance pattern with the central incisor was the most common. CONCLUSION: During maximal intercuspal position, there were cases in which not all of the teeth showed occlusal contact. During mandibular protrusive movements, one or more maxillary central incisors frequently joined in straight protrusion and the posterior teeth were disoccluded. Therefore, the anterior teeth protect the posterior teeth, and vice versa. Thus, mutually protected occlusion should be applied when reconstructing occlusion.

Full mouth prosthetic rehabilitation based on systemic analysis, diagnosis and treatment plan: a case report / 대한치과보철학회지

Data collection including checking the problem list and analyzing the etiology cannot be overemphasized in full mouth rehabilitation cases. It is well reported that favorable prognosis of prosthodontic treatment depends on accurate diagnosis. Seventy seven year old female patient presented with chief complaints of chewing pain on maxillary and mandibular left premolars and unesthetic existing prosthesis. Clinical evaluation, radiographic examination and cast analysis were performed to gather comprehensive data and problem lists. Treatment planning was based on collected data and related articles. Abutment evaluation, prognosis depending on various types of prosthesis, and maintenance were considered as well. Occlusal vertical dimension was increased to solve esthetic dissatisfaction and insufficient interocclusal space. Patient adaptation was verified with provisional restorations followed by diagnostic wax up. Function, esthetics and occlusal stability were verified during 8 week follow-up period. Prosthodontic reconstruction based on systemic analysis, diagnosis, and treatment plan led to satisfactory result after delivery of definitive prosthesis.

Gene expression of MC3T3-E1 osteoblastic cells on titanium and zirconia surface

PURPOSE: This study was performed to define attachment and growth behavior of osteoblast-like cells and evaluate the gene expression on zirconia compared to titanium. MATERIALS AND METHODS: MC3T3-E1 cells were cultured on (1) titanium and (2) zirconia discs. The tetrazolium-based colorimetric assay (MTT test) was used for examining the attachment of cells. Cellular morphology was examined by scanning electron microscopy (SEM) and alkaline phosphatase (ALP) activity was measured to evaluate the cell differentiation rate. Mann-Whitney test was used to assess the significance level of the differences between the experimental groups. cDNA microarray was used for comparing the 20215 gene expressions on titanium and zirconia. RESULTS: From the MTT assay, there was no significant difference between titanium and zirconia (P>.05). From the SEM image, after 4 hours of culture, cells on both discs were triangular or elongated in shape with formation of filopodia. After 24 hours of culture, cells on both discs were more flattened and well spread compared to 4 hours of culture. From the ALP activity assay, the optical density of E1 cells on titanium was slightly higher than that of E1 cells on zirconia but there was no significant difference (P>.05). Most of the genes related to cell adhesion showed similar expression level between titanium and zirconia. CONCLUSION: Zirconia showed comparable biological responses of osteoblast-like cells to titanium for a short time during cell culture period. Most of the genes related to cell adhesion and signal showed similar expression level between titanium and zirconia.

Finite element analysis of the effects of a mouthguard on stress distribution of facial bone and skull under mandibular impacts / 대한치과보철학회지

PURPOSE: The purpose of this study was to investigate the effects of a mouthguard on stress distribution under mandibular impact. MATERIALS AND METHODS: The FEM model of head consisted of skull, maxilla, mandible, articular disc, teeth, and mouthguard. The impact locations on mandible were gnathion, the center of inferior border, and the anterior edge of gonial angle. And the impact directions were vertical, oblique (45degrees), and horizontal. The impact load was 800 N for 0.1 sec. RESULTS: When vertical impact was applied, the similar stress and the distribution pattern was occurred without the relation of the mouthguard use (P>.05). The model with mouthguard was dispersed the stress to the teeth, the facial bone and the skull when the oblique (45degrees) impacts were happened. However, the stress was centralized on the teeth in the model without mouthguard (P<.05). The model with mouthguard was dispersed the stress to the teeth, the facial bone and the skull when the horizontal impacts was occurred. However, the stress was centralized on the teeth without mouthguard (P<.05). For all impact loads, stress concentrated on maxillary anterior teeth in model without mouthguard, on the contrary, the stress was low in the model with mouthguard and distributed broadly on maxillary anterior teeth, facial bone, and skull. CONCLUSION: The mouthguard was less effective at shock absorbing when vertical impact was added. However, it was approved that mouthguard absorbed the shock regarded to the oblique (45degrees) and horizontal impact by dispersing the shock to the broader areas and decreasing the stress.

A FEM study on stress distribution of tooth-supported and implant-supported overdentures retained by telescopic crowns / 대한치과보철학회지

PURPOSE: The purpose of this study was to investigate the stress distribution in mandibular implant-supported overdentures and tooth-supported overdentures with telescopic crowns. MATERIALS AND METHODS: The assumption of this study was that there were 2, 3, 4 natural teeth and implants which are located in the second premolar and canine regions in various distributed conditions. The mandible, teeth (or implants and abutments), and connectors are modeled, and analyzed with the commercial software, ANSYS Version 10.1. Stress distribution was evaluated under 150 N vertical load bilaterally on 3 experimental conditions - between canine areas, canine and 2nd premolars, 10 mm posterior to 2nd premolars. RESULTS: Overall, the case of the implant group showed more stress than the case of the teeth group in stress distribution to bone. In stress distribution to superstructures of tooth and implants, there was no significant difference between TH group and IM group and the highest stress appeared in TH-IV and IM-IV. The stress caused from bar was much higher than those of implant and tooth. TH group showed less stress than IM group in stress distribution to abutment teeth and implant. CONCLUSION: The results shows that it is crucial to make sure that distance between impact loading point and abutment tooth does not get too far apart, and if it does, it is at best to set abutment tooth on premolar tooth region. It will be necessary to conduct more experiments on effects on implants, natural teeth and bone, in order to apply these results to a clinical treatment.

Erratum: The effect of different crystallization temperature of the hydroxyapatite coating produced by ion beam-assisted deposition on anodizing-treated titanium disks on human osteosarcoma cells / 대한치과보철학회지

There has been a mistake, claimed and confirmed by all the authors of Vol 49(4), 2011, p. 333-340 issue, that first author should have been Hyun-Du Won instead of Ahran Pae.

Erratum: Finite element analysis of the effects of a mouthguard on stress distribution of facial bone and skull under mandibular impacts / 대한치과보철학회지

There has been a mistake, claimed and confirmed by all the authors of Vol 50(1), 2012, p. 1-9 issue, that first author should have been Il-Han Kim instead of Kwan-Tae Noh.

Erratum: A FEM study on stress distribution of tooth-supported and implant-supported overdentures retained by telescopic crowns / 대한치과보철학회지

There has been a mistake, claimed and confirmed by all the authors of Vol 50(1), 2012, p10-20 issue, that first author should have been Chang-Gyu Lee instead of Jang-Hyun Paek.

Clinical convergence angle and rounding radius on tooth preparation for zirconia all-ceramic crown / 대한치과보철학회지

PURPOSE: This article attempted to examine how teeth for restoration is made in a clinical practice and utilize it as future educational material of teeth formation and basic data for additional research. MATERIALS AND METHODS: This experiment investigated the models sent to milling center for production of zirconia crowns. After scanned with Lava CAD/CAM System (3M ESPE, Seefeld, Germany), they are measured on 'ImageJ (version 1.32j, National Institutes of Health, USA)' program and compared and analyzed. Convergence angle from mesio-distal surfaces and bucco-lingual surfaces of each teeth are measured. Also, bucco-lingual diameter of the region lowered as much as 0.4 mm from incisal edge in anterior teeth except canines.(This measure is defined as the Peak 0.4) The analysis of data between each group was conducted by Windows SPSS statistic program, and was proved significant on 95% confidence level by independent t-test, one-way ANOVA and multiple analysis (Sheffe test). RESULTS: The mean value of convergence angle was 18.67degrees. It is ranked as molar (26.70degrees) > premolar (16.87degrees) > anterior teeth (14.81degrees) in the order of mesio-distal convergence angle; anterior teeth (22.32degrees) > molar (20.93degrees) > premolar (15.41degrees) in the order of bucco-lingual convergence angle. The mean value of Peak 0.4 was 1.18 mm. CONCLUSION: Convergence angle of abutment of zirconia all ceramic crown has difference depending on the location in the arch. Due to the nature of production of zirconia all ceramic crown, convergence angle of abutment and line angle finishing degree can have an effect on internal suitability of restoration.