PURPOSE: The purpose of this study was to measure the tightening torque for dental implant in dental laboratory and to analyze of the effects of different tightening torque. MATERIALS AND METHODS: The tightening torque for dental implant in dental laboratory were measured by digital torque gauge. The length of abutment and analog were measured as tightening torque of manufacturer's instructions and the measured value. And the data were statically analyzed. RESULTS: The mean tightening torque of implant screw in dental laboratory was 1.563 +/- 0.332 Ncm. The external type implant system of total length were showing no significant differences but the internal type implant system had difference significant (P < 0.05) when compared with tightening torque. CONCLUSION: The implant prosthesis should be made under manufacturer's instructions especially as tightening torque of screw. For the fidelity of implant prosthesis, dental technician should learn how to use the torque gauge.
Dental Implants ; Dental Prosthesis ; Dental Technicians ; Humans ; Laboratories, Dental* ; Prostheses and Implants ; Torque*

The purpose of this study was to investgate and evaluate whether the recording information contained in the work authorization was performed properly and master casts were designed accurately according to the rationale and principles of the removable partial denture when the work authorization and the master casts were sent to the dental framework. the accurate recording of the work authorization sent to dental laboratory in Hwasun for removable partial denture framework, the normal form of the occlusal rest guiding plan of the surveyed crown using the surveyor, the location analysis of the occlusal rest seat, the design patten of the maxillary and mandibulary major connectors, the use of the surveyor on the master cast, the status of the secondary impression taken in the distal extension edentulous areas were investigated for this study. The following results were obtained : 1. In the status of the occlusal rest seat prepared in the abutment, the occlusal rest seat with normal form was 81.25%, 95.45%, that without form was 6.25%, 0.00%, respectively in Class I and Class II on the maxillary cast and the occlusal rest seat with normal form was 76.92%, 95.45%, that without form was 7.69%, 0.00% respectively in Class I and Class II on the mandibular cast. 2. In the status of the guiding plan, the guiding plan with the normal form was 79.17%, 86.36% that with abnormal form was 20.84%, 13.64% respectively in Class I and Class II on the maxillary cast and the guiding plan with normal form was 79.49%, 77.27%, that with abnormal form was 20.51%, 22.73% respectively in Class I and Class II on the mandibular cast. 3. The abutment splinting in the distal extension removable partial denture was 20.78%, 27.27%, respectively in Class I and Class II on the maxillary cast and was 25.64%, 13.64% respectively in Class I and Class II on the mandibular cast. 4. The location and form of the major connector delineated on the maxillary and mandibular master cast was 95.83%, 98.41% respectively. 5. The delineation and recording on the work authorization was incomplete as group II(73.33%), group I(14.07%), group III(12.59%) and group IV (0.00%) in investigating the contents of the work authorization. 6. Aker's clasp of the types of the direct retainer was nots used 72.22%, 74.60%, in the maxillary and mandibular casts respectively. 7. The location of the indirect retainer delineated on the maxillary and mandibular master cast was 51.43%, 50.82% respectively. 8. The types of metal used were mostly Cr-Co non-precious metal alloy and the cases using color coding on the drawing paper of work authorization were not observed. 9. The cases taking secondary impression in the distal extension removable partial denture were 45.71%, 52.46% respectively in the maxillary and mandibular master cast. 10. The delineation of tripoding or reference line on the master cast was not observed in surveying procedure.
Alloys ; Clinical Coding ; Crowns ; Denture, Partial, Removable ; Laboratories, Dental ; Splints

The dental profession is currently experiencing a technology explosion. Processes are being replaced by modern, inexpensive, and precise techniques that can be used to solve complex restorative problems. Electrical discharge machining (DEM, known as spark erosion in Europe) is a nonconventional, industrial technique that has application in dentistry. EDM may be defined as a metal removal process using a series of sparks to erode material from a workpiece in a liquid medium under carefully controlled conditions. EDM is recently adopted in the dental laboratory to fabricate precision attachments, hybrid telescope crowns, Ti-ceramic crowns. EDM has also been used to achieve a passive precision metalto-metal fit between the substructure bar and the removable superstructure and to correct the fit of implant retained restorations. in this article, a brief history and explanation of EDM is discussed and a description of the use of this process for fabricating attachments and crowns or for correcting the fit of cast restorations is presented.
Crowns ; Cytochrome P-450 CYP1A1 ; Dentistry ; Explosions ; Laboratories, Dental ; Telescopes

OBJECTIVES: To investigate the relationship between job stress and the variables associated with the organizational effectiveness of dental technicians. METHODS: The job stresses were divided into the following six components; somatization, obsessive-compulsive, interpersonal sensitivity, depression, anxiety, and hostility. The organi-zational effectiveness variables in this study included job satisfaction, occupational commitment, organizational commitment and intent to leave. The sample used in this study consisted of 248 dental technicians working in hospitals and dental laboratories. The data were collected with self-administered questionnaires between March 16 and April 29 in 2002, and the results analyzed with ANOVA and multiple regression analysis. RESULTS: Firstly, job stress of dental technicians was found to be significantly different in relation to the number of workers at the workplace and the working hours. The level of job stress was the highest when the number of workers were more than 10, or when the daily working hours were over 12. Secondly, of the six variables of job stress, five variables of somatization, interpersonal sensitivity, depression, anxiety, and hostility were found to have significant negative correlations with job satisfaction. Thirdly, all six job stress variables were found to have significant negative correlations with the occupational and organizational commitments of the dental technicians. Finally, depression was the only job stress variable found to have a significant effect on the dental technicians' intent to leave. CONCLUSIONS: The results of this study indicate that personal and organizational efforts are very important to improve the organizational effectiveness in reducing work related stress. Organizational support, especially for managing the depression of dental technicians is recommended.
Anxiety ; Dental Technicians* ; Depression ; Hostility ; Humans ; Job Satisfaction ; Laboratories, Dental ; Questionnaires

STATEMENT OF PROBLEMS: There are only a few studies available that deal with the clinical behavior of ceromer systems as potential substitutes for metal-ceramic crowns. PURPOSE: This prospective study was initiated to evaluate the clinical performance of 35 Sculpture crowns after 2 years in service. MATERIAL AND METHODS: Thirty five Sculpture crowns were placed for 20 patients (7 men and 13 women). All patients were treated by the same dentist, and all restorations were fabricated by the same dental laboratory. Crown placement involved both the anterior and posterior regions of the dental arches. Patients were evaluated by two examiner at baseline, 12, and 24 months using the CDA quality assessment system in addition to periodontal criteria. RESULTS: Of 34 crowns remaining in the study after 2 years, only one crown had experienced a marginal fracture. The crown was replaced as a result of recurrent caries. All remaining crowns were ranked as either excellent or acceptable for surface and color, anatomic form, and marginal integrity. CONCLUSION: The 2-year clinical observations and ranking with the CDA quality assessment criteria supported the conclusion that Sculpture crowns may be used in substitutes for metal- ceramic crowns.
Ceramics ; Crowns* ; Dental Arch ; Dentists ; Humans ; Laboratories, Dental ; Male ; Prospective Studies ; Sculpture*

PURPOSE: This study was performed to develop a proper self-administered survey instrument which can be used to measure psychiatric stress symptoms in Korean dental laboratory technicians, and to investigate the relationship between the symptom dimensions and stress inducing factors, such as psychological distress, stress inducing overload, work demand, work procedure and so forth in them. METHODS: Prepared questionnaires were mailed to 1,000 dental laboratory technicians who were systematically selected. There were 786 responses to the questionnaires. All the data obtained were analyzed with SAS program. RESULTS: Fifty items for the stress symptom checklist for dental technician(SCLD) were selected after a pilot test, interviews and literature reviews. Stress symptoms were classified into the following 6 categories, i.e, somatization, obsessive-compulsive, interpersonal sensitivity, depression, anxiety, and hostility symptom. Factor analysis for validity was carried out for corroboration, using the SCL-90-R as a standard. CONCLUSION: SCLD had the reasonable reliability and validity. We believe that this study provides validity and reliability for new self-report questionnaire, it will make a significant contribution to assessment of stress symptoms.
Anxiety ; Checklist ; Dental Technicians ; Depression ; Hostility ; Humans ; Laboratories, Dental* ; Postal Service ; Reproducibility of Results ; Surveys and Questionnaires

This article reviews the topic of how to identify and develop a removable partial denture (RPD) path of placement, and provides a literature review of the concept of the RPD path of placement, also known as the path of insertion. An optimal RPD path of placement, guided by mutually parallel guide planes, ensures that the RPD flanges fit intimately over edentulous ridge structures and that the framework fits intimately with guide plane surfaces, which prevents food collecting empty spaces between the intaglio surface of the framework and intraoral surfaces, and ensures that RPD clasps engage adequate numbers of tooth undercuts to ensure RPD retention. The article covers topics such as the causes of obstructions to RPD intra-oral seating, the causes of food collecting empty spaces that may exist around an RPD, and how to identify if a guide plane is parallel with the projected RPD path of placement. The article presents a method of using a surgical operating microscope, or high magnification (6-8x or greater) binocular surgical loupes telescopes, combined with co-axial illumination, to identify a preliminary path of placement for an arch. This preliminary path of placement concept may help to guide a dentist or a dental laboratory technician when surveying a master cast of the arch to develop an RPD path of placement, or in verifying that intra-oral contouring has aligned teeth surfaces optimally with the RPD path of placement. In dentistry, a well-fitting RPD reduces long-term periodontal or structural damage to abutment teeth.
Dentistry ; Dentists ; Denture, Partial, Removable* ; Dentures ; Humans ; Laboratories, Dental ; Lighting ; Prosthodontics ; Telescopes ; Tooth

The objective of this study was to characterize the mechanical properties of Y2O3-containing glass infiltrated ceramic core material, which was made by pressureless powder packing method. A pure alumina powder with a grain size of about 4micrometer was packed without pressure is silicon mold to form a bar shaped sample, and applied PVA solution as a binder. Samples were sinterd at 1350degrees C for 1 hour. After cooling, Y2O3-containing glass (SiO2, Y2O3, B2O3, Al2O3, ect) was infiltrated to the sinterd samples at 1300degrees C for 2 hours and cooled. Six different proportions Y2O3 of were used to know the effect of the mismatch of the thermal expansion coefficient between alumina powder and glass. The samples were ground to 3x3x30 mm size and polished with 1microneter diamond paste. Flexural strength, fracture toughness, hardness and other physical properties were obtained, and the fractured surface was examined with SEM and EPMA. Ten samples of each group were tested and compared with In-Ceram(TM) core materials of same size made in dental laboratory. The results were as follows : 1. The flexural strengths of group 1 and 3 were significantly not different with that of In-Ceram, but other experimental groups were lower than In-Ceram. 2. The shrinkage rate of samples was 0.42% after first firing, and 0.45% after glass infiltration. Total shrinkage rate was 0.87%. 3. After first firing, porosity rate of experimental groups was 50%, compared with 22.25% of In-Ceram. After glass infiltration, porosity rate of experimental groups was 2%, and 1% in In-Ceram. 4. There was no statistical difference in hardness between two materials tested, but in fracture toughness, group 2 and 3 were higher than In-Ceram. 5. The thermal expansion coefficients of experimental groups were varied to 4.51~5.35x10-6/degrees C according to glass composition, also the flexural strengths of samples were varied. 6. In a view of SEM, many microparticles about 0.5microneter diameter and 4microneter diameter were observed in In-Ceram. But in experimental group, the size of most particles was about 4microneter, and a little microparticles was observed. The results obtained in this study showed that the mismatch of the thermal expansion coefficients between alumina powder and infiltrated glass affect the flexural strength of alumin/glass composite. The Y2O3-containing glass infiltrated ceramic core made by powder packing method will takes less time and cost with sufficient flexural strength similar to all ceramic crown made with slip casting technique.
Aluminum Oxide* ; Ceramics ; Edible Grain ; Crowns ; Diamond ; Fires ; Fungi ; Glass* ; Hardness ; Laboratories, Dental ; Porosity ; Silicones

The purpose of this article is to introduce a new virtual orthodontic treatment (VOT) system, which can be used to construct three-dimensional (3D) virtual models, establish a 3D virtual setup, enable the placement of the virtual brackets at the predetermined position, and fabricate the transfer jig with a customized bracket base for indirect bonding (IDB) using the stereolithographic technique. A 26-year-old woman presented with anterior openbite, crowding in the upper and lower arches, and narrow and tapered upper arch, despite having an acceptable profile and balanced facial proportion. The treatment plan was rapid palatal expansion (RPE) without extraction. After 10 days of RPE, sufficient space was obtained for decrowding. After a 10-week retention period, accurate pretreatment plaster models were obtained using silicone rubber impression. IDB was performed according to the protocol of the VOT system. Crowding of the upper and lower arches was effectively resolved, and anterior openbite was corrected to normal overbite. Superimposition of the 3D virtual setup models (3D-VSM) and post-treatment 3D virtual models showed that the latter deviated only slightly from the former. Thus, the use of the VOT system helped obtain an acceptable outcome in this case of mild crowding treated without extraction. More cases should be treated using this system, and the pre- and post-treatment virtual models should be compared to obtain feedback regarding the procedure; this will support doctors and dental laboratory technicians during the learning curve.
Adult ; Crowding ; Female ; Humans ; Laboratories, Dental ; Learning Curve ; Open Bite ; Overbite ; Retention (Psychology) ; Silicone Elastomers

PURPOSE: In literature, many studies compare survival rates of different types of FPDs. Most of them compared restorations, which originated from one university, but from different clinicians. Data about restoration survival rates by only one experienced dentist are very rare. The aim of this study was to evaluate the survival rate of allceramic FPDs without the blurring effects of different clinicians. MATERIALS AND METHODS: 153 veneeredzirconia FPDs were observed for follow-up. 22 patients received 131 single crowns and 22 bridges. Because of the different bridge lengths, one unit was defined as a restored or replaced tooth. In total, 201 units were included. Only the restorations performed by the same clinician and produced in the same dental laboratory from 2011 to 2016 were included. Considered factors were defined as “type of unit”, “type of abutment”, “intraoral region”, and “vitality”. Modified UHPHS criteria were used for evaluation. Statistical analysis was performed using cox-regression. RESULTS: 189 units (94.0%) showed no kind of failure. 5 chippings (2.4%) could be corrected by intraoral polishing. 4 units (1.9%) exhibited spontaneous decementation. These polishable and recementable restorations are still in clinical use. Chippings or decementations, which lead to total failure, did not occur. One unit was completely fractured (0.5 %). Biological failures (caries, periodontitis or periimplantitis) did not occur. The statistical analysis of the factors did not reveal any significant differences. CONCLUSION: Modern all-ceramic FPDs seem to be an appropriate therapy not only for single restorations but for complex occlusal rehabilitations.
Crowns ; Dentists ; Follow-Up Studies ; Humans ; Laboratories, Dental ; Periodontitis ; Survival Rate ; Tooth