Porcelain Jacket Research Articles

Study on the difference of fault detection effect of AC leakage current live test technology under operating voltage on different insulating parts of MOA

Resistive current live test plays an important role in the technical supervision of metal oxide arrester (MOA). At the same time, there are some conditions that MOA can not find hidden dangers and defects through AC leakage current live test. This paper puts forward an assumption: the AC leakage current live test technology under operating voltage has different fault detection effects on different insulating parts of MOA. It is found that in the overall AC leakage current composition of the arrester, the resistance sheet and porcelain jacket account for a large proportion, and the proportion of FRP core insulating support rod and epoxy resin insulating cylinder is very small, so the AC leakage current test under operating voltage can effectively detect the faults on the resistance sheet and porcelain jacket, and it is difficult to detect the insulating support rod Fault on insulating cylinder (or insulating package). This study clears a blind spot of the safe operation of the arrester, provides a reference for the condition based maintenance of the arrester, and improves the operation and maintenance level of the arrester.

Editorial: Dental Ceramics: From Science and Technology to Clinical Application

Editorial: Dental Ceramics: From Science and Technology to Clinical Application

Dentist’s Perspective Regarding Usage of Different Fixed Prosthesis Removal Systems in Islamabad and Rawalpindi

Background: Crowns and multi-unit fixed partial dentures have a limited lifetime. They fail for a number of reasons. The removal of provisional crowns and bridges is generally simple, however for permanent crowns, it becomes more challenging. Careful removal of FPD can help a dentist simplify a resto or endo procedure. The aim of this article was to analyze the different methods available for the removal of crowns and bridges and their awareness among dental practitioners Study Design & location: This was a cross-sectional study based on a questionnaire. The questionnaire was filled by a total of 250 general and specialist dentists who were practicing in various individual and group-based dental practices as well as private and government setups of Islamabad and Rawalpindi. Methodology: The questionnaire comprised a total of 13 questions to find out dentists' views about the usage of different system’s available for dental crowns and FPD removal. Participants were selected by random sampling. The results were then analyzed using SPSS version 23. Frequencies, percentages of different variables used in the study were calculated to identify the co-relation among different attributes. P-value of less than or equal to 0.05 was considered statistically significant. Results: The study reflected that out of those who answered, 247 dental professionals (98.5 %) preferred using hemostats or Morrell sliding hammer or a combination of both as they offered better control of force. A small percentage (approx 2%) of dentists used diamond or carbide burs as their first preference to trim off old crowns. Clinicians rarely used laser due to its high cost and less availability and its effectiveness primarily related to Porcelain jacket/ Zirconium crowns. Conclusion: It was concluded from this study that the majority of dentists preferred Morrell type crown remover with sliding hammer due to its ease of availability, universal acceptance, simple to use and because as it offered better control of force as opposed to spring-lock type Keywords: Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure.

PENATALAKSANAAN FRAKTUR ELLIS KELAS III 11 DENGAN PULPEKTOMI DAN RESTORASI MAHKOTA PASAK

A 19-year-old male patient came to Unud Hospital with a complaint that his upper right front tooth was broken. The patient's right front toothaches when he consumes cold food or drinks and bleeds every morning. Pain still exists even if food or cold drinks are removed. Complaints felt since 7 months ago. The tooth now feels pain but is not as severe as the initial tooth fracture. Patients have consumed mefenamic acid to reduce pain. The tooth has never been treated by a dentist. The patient is now treated with pulpectomy accompanied by a fused to metal porcelain jacket crown restoration with a cast post-core. After controlling for one week after treatment, the desired result is the loss of subjective and objective complaints in the patient.

Management of Ellis Class III Fracture in Two Maxillary Incisivus

Introduction. Trauma injury in the oral cavity due to collisions can cause tooth fracture. Ellis class III fracture is a fracture of the crown with an open pulp. Teeth with exposed pulp will cause irritation of the pulp resulting in pulp inflammation (pulpitis). One visit pulpectomy and jacket crown with posts were carried out to achieve optimal dental functions. Case report. A 27-year-old male patient came to Dental Hospital of Universitas Gadjah Mada complained about his broken front teeth due to accident three days earlier. The crown of the maxillary right lateral incisor and the maxillary left central incisor with open pulp was seen. The tooth 11 was avulsion, which lost at the location of accident. The diagnosis of 12 and 21 were Ellis class III fracture. Initially an infiltration anaesthesia was done, followed by one visit root canal treatment (RCT). On the second visit, the teeth were asymptomatic, hence the jacket crown preparation and fiber post insertion were performed. On the third visit, a porcelain jacket crown was cemented into teeth 12 and 21. A week later the patient came for recall and no complaints were noted. Conclusion. One visit pulpectomy followed by restoration with porcelain crown and fiber posts can be undertaken to achieve the optimal functions of teeth, namely aesthetic, mastication, phonetics, and protection of supporting tissues function.

Dental application of glass-ceramic materials for aesthetic restoration

Porcelain is the first ceramic material to be introduced into dentistry. Porcelain jacket crown was introduced by Dr. Charles H Land in 1886, which was an excellent aesthetic dental restoration but has not been widely used due to high firing shrinkage and low tensile strength. Then metal-ceramic system, which combines the esthetic properties of ceramics and the mechanical properties of metals, was introduced and nowadays it is still used in dental clinical field. However, the metal-ceramic system has shown some problems, such as increased lightness by reflection of light at opaque layer, shadow beneath the gingival line due to the block-out of light by metal coping, exposure of metal in margin part, bond failure between metal and porcelain, oxidation of metal coping during firing the porcelain, etc. Recently, along with the advance of fabrication methods of dental ceramics, the all-ceramic restorations with high esthetic and mechanical properties has increased and gradually replaced metal-ceramic restorations. Especially, CAD/CAM technology has opened a new era in fabricating the dental ceramic restorations. This overview will take a look at the past, present and future possibility of the dental ceramic materials.

Concurrent Occurrence of Bilateral Hypodontia and Microdontia in a Nonsyndromic Paediatric Patient: A Case Report

Hypodontia is a developmental dental anomaly defined as the absence of one or more primary or permanent teeth excluding third molars. It can be associated with syndrome or nonsyndromic condition accompanied with other developmental dental anomalies like microdontia. Bilateral occurrence of hypodontia alongside microdontia is a rare condition. This case report presents a rare occurrence of bilateral hypodontia and microdontia in a nonsyndromic patient. Owing to its nonsyndromic background, other parameters like developmental delay, height, weight and body mass index are used as the predicting factors for the occurrence of hypodontia. Developmental milestones are one of the important factors in deriving the treatment plan. Treatment options in this case were directed at delaying the treatment until the eruption of the permanent successor teeth followed by the use of mini-implants for hypodontia, porcelain jacket crown for microdontia and the orthodontic treatment for final space closure.

MONOLITHIC LITHIUM-DISILICATE GLASS-CERAMIC RESTORATIONS

In a pursuit for perfect esthetic and natural appearance of restorations in contemporary dentistry, porcelain fused to metal restorations are gradually being replaced by all-ceramics. All-ceramic restorative systems are not a new concept. They were first introduced with the so-called “porcelain jacket crown” in the 1900s by Charles H.Land, fabricated with high-fusing feldspathic porcelain on platinum foil matrix. Because of the low strength of this porcelain, the failure rate was very high and they were slowly abandoned. In the last 10 years with the introduction of lithium-disilicate class ceramics IPSe.max System (Ivoclar Vivadent) with a strength of 470 MPa monolithic restorations made a big comeback. Monolithic or full-contour lithium-disilicate restorations can be stained and glazed for more natural tooth colour look. The ideal restoration shade is optimally reproduced by means of the IPS e.max Shade Navigation App. It facilitates the material selection, leads to results that feature optimum shade match and thus provides efficiency and reliability. This material has two forms: a homogeneous ingot with various degrees of translucency and opacity used with hot-pressed technology Emax Press and a pre-crystallized block used with CAD/CAM technology Emax CAD. Regarding the strength of the material, pressed lithium disilicate is 11% stronger than the CAD/CAM lithium disilicate according to Ivoclar’s 2011 scientific report. Pressable lithium disilicate restorations demonstrated a 98.4% survival rate. Machineable lithium disilicate restorations (IPS e.max CAD) demonstrated a 97.9% survival rate. The pressing technique demonstrated a significantly smaller marginal gap than the CAD/CAM technique. Some in vitro studies have pointed out that lithium disilicate monolithic crowns and FDPs, both CAD/CAM and hot-pressed, are more resistant to fatigue fracture compared to bilayered, hand veneered ones, showing higher fracture loads (1900 N), that are comparable to the metal-ceramic standard. Clinical outcomes of different IPS e.max lithium disilicate prostheses like single crowns, 3 unit bridges, veneers, inlays and onlays, both in the bilayered and monolithic forms, in a 4-year retrospective study reported: 0.91% for monolithic and 1.83% for bilayered single crowns (twice the rate of the monolithic); 4.55% for monolithic FDPs; 1.3% for monolithic and 1.53% for bilayered veneers; and 1.01% for monolithic inlays/onlays. This research supports the use of monolithic lithium disilicate restorations in everyday treatment of choice for high-strength and esthetic indirect treatments, whether for the anterior or posterior regions of the mouth. The material offers specific advantages to dentists such as the ability to provide strong and durable restorations with highly esthetic characteristics without metal. More clinical studies for the esthetic outcome of monolithic restorations are needed in the future.

Accidentally Broken Lateral Incisor Tooth at the Gingival Margin Treated by Endodontics, Cast Post and Core Finally Porcelain Jacket Crown: A Case Report

A successful treatment of a badly broken tooth in accidental case depends not only on good endodontic therapy but also on good prosthetic reconstruction of the tooth after the endodontic treatment is complete. In accidental case, sometimes it is found that there is very little or no clinical crown after root canal treatment. In such cases, additional retention & support of the restoration are difficult to achieve. In this case report endodontically treated tooth by suing cast post is discussed to achieve additional retention and supportBangladesh Journal of Dental Research and Education Vol.5(2) 2015: 73-74

A Study of Patient Satisfaction with Maxillary Anterior Teeth Restorations and Desirable Esthetic Treatment Options

Method:650 patients participated in the study , divided into 4 age groups. A structured, interviewer- guided questionnaire was used to identify patient satisfaction with their general dental appearance, cosmetic elements and desired treatments .Their maxillary anterior teeth status was classified into 4 groups: (1) Composite filling group (CFG) (2) Porcelain jacket crown group (PJCG) (3) Fixed partial denture group (FPDG) (4) Removable partial denture group (RPDG). The participants judged appearance and tooth colour using 3-point scale: dissatisfied, moderately dissatisfied and satisfied. Their desired esthetic treatment options were assessed. Results: The overall rating of satisfaction was moderate; almost 39.5% patients were completely satisfied with their dental appearance and tooth colour. A significant difference was observed for both the dental appearance and the tooth colour between different maxillary anterior teeth status groups and between different age groups (p < 0.05) .The majority of individuals with CFG and FPDG were completely satisfied, while those with PJCG and RPDG were dissatisfied with their dental appearance and tooth colour (p < 0.05). 50.9% patients wished to have their teeth whitened. Conclusion: Aesthetic attitudes towards the maxillary anterior teeth appearance and colour differed both between different age groups and different maxillary anterior teeth status groups. Dissatisfaction with tooth color,protruding teeth and unesthetic fillings were common and females were more dissatisfied than males in appearance.Tooth whitening was the most desired treatment to improve the esthetics.

From Ceramics to Ceramic Steel: Genesis

Ceramics were introduced in dentistry since the 16th century as dental porcelain, primarily for the manufacture of porcelain teeth. Improved technology saw porcelain jacket crowns, metal ceramic systems with better bonding techniques of different alloys to porcelain, bonded foil systems and then the

Cost-effectiveness of restorations

Objective To determine the relative cost-effectiveness of alternative methods for restoring large tooth substance loss in adults. Methods Long-term survival estimates and discounted costs for 245 large indirect restorations were used to calculate their incremental cost-effectiveness over 15 years when compared with direct placement Class II cusp-overlay amalgams and Class IV multisurface resin composites, placed in 100 patients from three private dental practices. Results The direct placement restorations were more cost-effective than the indirect restorations at all time intervals over the 15-year study period. The full gold crown and the ceramometal crown were the most cost-effective indirect posterior and anterior restorations respectively. The cast gold onlay and the porcelain jacket crown were the least cost-effective indirect posterior and anterior restorations respectively. Conclusions When clinically practicable, large direct placement restorations should be placed initially in preference to indirect restorations.

Long-term cost-effectiveness of single indirect restorations in selected dental practices.

To determine the relative cost-effectiveness of alternative methods for restoring large tooth substance loss in adults. Long-term survival estimates and discounted costs for 245 large indirect restorations were used to calculate their incremental cost-effectiveness over 15 years when compared with direct placement Class II cusp-overlay amalgams and Class IV multisurface resin composites, placed in 100 patients from three private dental practices. The direct placement restorations were more cost-effective than the indirect restorations at all time intervals over the 15-year study period. The full gold crown and the ceramometal crown were the most cost-effective indirect posterior and anterior restorations respectively. The cast gold onlay and the porcelain jacket crown were the least cost-effective indirect posterior and anterior restorations respectively. When clinically practicable, large direct placement restorations should be placed initially in preference to indirect restorations.

Reasons for the placement and replacement of crowns in general dental practice.

The purpose of the study was to apply established methods to survey reasons for the placement and replacement of crowns in general dental practice in the United Kingdom. One hundred and twenty-eight general dental practitioners were recruited. Participants recorded the principal reason for the provision of each initial and replacement crown they provided over a 12-week period. Overall, data were collected from 92 practitioners in respect of 1714 patients and 2164 crowns, of which 1452 (67%) were initial placements and 712 (33%) replacements. The teeth most frequently crowned were maxillary incisors (33%), with 72% of the crowns surveyed being of the porcelain bonded to metal variety. Overall 64% of the initial placement crowns were provided because of restoration failure (26%) or tooth fracture (38%). The most common reason for crown replacement was crown failure (27%). It is concluded that surveys of the type reported may provide new insights into the reasons for and pattern of provision of initial placement and replacement crowns in clinical practice. In this study the most common reason for the provision of initial placement crowns was tooth fracture. The most common reason for the replacement of crowns, notably porcelain jacket crowns, was crown fracture.

In vitro study of fracture incidence and compressive fracture load of all-ceramic crowns cemented with resin-modified glass ionomer and other luting agents

Statement of problem. Anecdotal reports based on clinical observation have recently linked resin-modified glass ionomer luting agents with postcementation fracture of all-ceramic crowns. Purpose. This study evaluated the fracture incidence of In-Ceram and VitaDur Alpha porcelain jacket all-ceramic crowns cemented with 5 luting agents (Fuji I, Fuji Plus, Vitremer, Advance, and Panavia 21) during 2 months storage in 0.8% NaCl solution. Material and methods. Fifty human maxillary premolar teeth were prepared for each ceramic system and divided into 5 subgroups of 10 teeth to be cemented with 5 luting cements. Specimens were observed for fracture lines and crack initiation at storage times up to 2 months. Incidence of fracture was analyzed with Fisher’s Exact test. Specimens that did not fracture during storage were loaded in compression to failure. Failure loads were analyzed by analysis of variance and multiple pairwise comparisons. Results. Only all-ceramic crowns cemented with Advance cement fractured during the 2-month observation period, and porcelain jacket crowns were found to fracture earlier and more frequently than In-Ceram crowns. Cracks initiated at the crown margin, and multiple crack lines were found as the time of storage increased. In-Ceram crowns were significantly stronger (140 ± 21.5 kg) than porcelain jacket crowns (98.6 ± 17.8 kg) at P <.05. For In-Ceram crowns, cement type did not influence failure load while for porcelain jacket crowns, Fuji I (110.5 kg) was significantly higher than Vitremer (86.6 kg) at P <.05. Conclusions. For the cements studied, only crowns cemented with Advance cement demonstrated fracture during 2-month storage. Results for the true resin-modified glass ionomer cements do not support anecdotal reports of fracture of all-ceramic crowns cemented with these materials. (J Prosthet Dent 1998;80:699-707.)

焼結金属を用いた陶材焼付前装冠に関する基礎的検討

Newly-developed all ceramic and metal ceramic crowns are alternatives to conventional porcelain jacket crowns (PJC) and porcelain fused to metal crowns (PFM).Two types of metal ceramic crowns, made by sintering precious metals, were investigated as to adaptation and strength in clinical applications.The results were as follows:1. The prime factors in adaptation of crowns are the method of impression used for making a duplication die with the HERATEC (HT) system, and the method of applying the bonding agent between duplication die materials and the metal of the DEGUSINT (DG) system.2. The strengths of these new metal ceramic crowns depend on the thickness of the sintered metal layer.3. The strength of the HT crown is equal to the value of PJC and is one-third that of PFM, while the strength of the DG crown is two times that of the HT crown and the PJC and 0.7 times that of PFM.4. To increase the strength of these new crowns, with the HT system, the thickness of the sintered metal layer and the mechanical strength of Au-Pd layer must be increased, and the number and the diameter of bubbles in the metal ceramic conjunction layer, should be decreased. With the DG system, it is necessary to increase the mechanical strength of the sintered metals. Thus it is necessary to investigate the sintering conditions.

The effect of cement thickness on the fracture strength of all-ceramic crowns.

The effect of increasing cement thickness on the fracture strength of aluminous porcelain jacket crowns was investigated in this study. Thirty-three aluminous porcelain jacket crowns were divided into three groups. In Group 1, only platinum foil was used to provide cement space. In Group 2 two layers and Group 3 four layers of die spacer were painted onto the metal die before impression taking. Each crown was cemented onto a metal die with zinc phosphate cement and loaded until fracture. The maximum force to break each crown was recorded. The average fracture load was 408 N for Group 1,365 N for Group 2 and 324 N for Group 3. ANOVA (SPSS) found a significant difference (p < 0.05) between groups. A Scheffe Test revealed a significant difference between Groups 1 and 3. It was concluded that increasing the cement thickness above 70 microns reduced the fracture strength of porcelain jacket crowns.

支台材料がＣｅｒａｍｉｃｓ Ｊａｃｋｅｔ Ｃｒｏｗｎの応力分布に及ぼす影響 三次元光弾性実験による応力解析

A photoelastic stress analysis technique has been conducted for many years as a test to analyze stress distribution of porcelain jacket crowns under a load. The purpose of this study was to evaluate the alteration of stress distribution on ceramic jacket crowns by each abutment material of different elasticity. On the assumption that the jacket crown consists of castable ceramics (DICOR) and three different abutment materials had metal cores (12% Au-Ag-Pd alloy), a resin core (photocuring composite resin) and a natural tooth, the crown and the abutment tooth model were made of epoxy resin. And the stress analysis of the ceramic jacket crown was studied by three-dimensional stress freezing photoelasticity experimental technique.The boundary stress in the portion with the added load reached the maximum value in all abutment teeth. The magnitude of boundary stress increased with the decrease in the elastic modulus of the abutment material. Especially, when the abutment was a resin core or a natural tooth, high boundary stress was observed around the labial cervix.

Recent Developments in Restorative Dental Ceramics

Since the introduction of porcelain jacket crowns in the early 1900s, dental ceramics have been praised for their esthetic appearance. But there's more to consider: other benefits, longevity, limitations. This review addresses major developments in modern dental ceramics and metal-ceramics.

In vitro comparison of conventional crowns and a new all-ceramic system

Thirty-three crowns of similar size and shape were constructed to fit a standard brass die. Eleven crowns were manufactured from each of the following groups of materials: metal-ceramic, aluminous porcelain and a new all-ceramic system based on a glass infiltrated alumina coping. The overall fitting accuracy of each crown was determined using a low viscosity silicone paste, prior to cementation onto brass dies with zinc phosphate cement. The average film thickness was 95,154 and 123 pin respectively. Each cemented crown was loaded to fracture. The mean load to failure of the glass infiltrated alumina crowns was significantly greater than that of the aluminous porcelain jacket crowns ( P < 0.0001), but not significantly different from the metal-ceramic crowns.