Metal-ceramic Crowns Research Articles

Comparison of Marginal Integrity and Surface Roughness of Selective Laser Melting, CAD-CAM and Digital Light Processing Manufactured Co-Cr Alloy Copings

The purpose of the present study was to evaluate the influence of fabrication techniques on the surface micro-roughness (Ra) and marginal misfit of cobalt chromium (CoCr) copings. A mandibular first molar was prepared for a metal ceramic crown. Forty metal copings were prepared and divided into groups (n = 10). Group 1, Casting-Lost wax technique (Cast-LWT), Group 2, CAD-CAM, Group 3, Selective laser melting (SLM), and Group 4, Digital light processing-Cast (DLP-Cast). Ra was measured using laser profilometry and marginal misfit was analyzed with Micro-CT. Analysis of variance (ANOVA), Tukey multiple comparison, and correlation coefficient tests were applied (p < 0.05). SLM technique showed the highest Ra (2.251 ± 0.310 μm) and the Cast-LWT group presented the lowest Ra (1.055 ± 0.184 μm). CAD-CAM copings showed statistically lower Ra compared with SLM samples (p = 0.028), but comparable Ra to DLP-Cast (p > 0.05). CoCr copings fabricated from the DLP-Cast technique demonstrated the highest marginal misfit (147.746 ± 30.306 μm) and the lowest misfit was established by SLM copings (27.193 ± 8.519 μm). The SLM technique displayed lower marginal misfit than DLP-Cast and CAD-CAM (p = 0.001), but comparable misfit to Cast-LWT copings. Ra influenced the marginal misfit in CAD-CAM, SLM, and DLP-Cast technique-fabricated copings. (p < 0.01). Marginal misfit and Ra of CoCr copings are contingent on the different fabrication techniques.

Are ceramic implant-supported single crowns clinically better than metal-ceramic implant-supported single crowns?

Data sources Data was collected from six databases (Medline, Embase, Web of Science, The Cochrane Central Register of Controlled Trials [CENTRAL], China National Knowledge Infrastructure [CNKI] and Chinese Biomedical Literature Database). Studies published in English and Chinese languages comparing ceramic and metal-ceramic implant-supported fixed dental prostheses (FDPs) were searched. The literature search was performed on studies published until 2018. Manual search of the reference lists of the identified articles was also performed to find related review articles and studies.Study selection Randomised controlled trials (RCTs), prospective and retrospective cohort studies involving the comparison of ceramic and metal-ceramic implant-supported FDPs were selected using the PICOS model for the meta-analysis. For ceramic and metal-ceramic single crowns, the survival rate, marginal adaptation, marginal bone loss, pocket probing depth, crown colour match and mucosal discolouration were assessed. The authors also included studies on survival rate of implant-supported fixed partial dental prostheses (FPDPs) in this meta-analysis.Data extraction and synthesis Two investigators independently screened the articles from the literature search and extracted and analysed data from the included studies. The quality of the included RCTs were assessed using the Cochrane collaboration tool for assessment of risk of bias. For the selected non-randomised studies, the quality and risk of bias were assessed using the Newcastle-Ottawa scale. Twenty studies were included in data synthesis.Results Of the selected 20 studies, ten were RCTs and ten were prospective or retrospective cohort studies.Conclusions The results of this study can be useful to clinicians in making decisions between ceramic and metal-ceramic implant-supported single crowns. This study concluded that the ceramic implant-supported single crown has better crown colour match over a metal-ceramic single crown, but poorer marginal adaptation, and there was no difference observed in other parameters studied (survival rate, marginal bone loss, pocket probing depth and mucosal discolouration). The conclusions on survival rate of implant-supported FPDPs needs to be further evaluated with RCTs with larger samples.

Fit of metal-ceramic crowns

Aim: To evaluate the influence of cobalt-chromium (Co-Cr) coping fabrication methods and ceramic application on the marginal and internal fit of metal-ceramic crowns. Methods: Co-Cr copings for metal-ceramic crowns were prepared by lost wax casting or CAD-CAM machining of sintered blocks. The fit was analyzed using the silicone replica technique at four assessment points: marginal gap (MG), axial wall (AW), axio-occlusal (AO) angle, and central occlusal (CO) wall. After the initial analysis, the copings were ceramic-veneered with the layering technique, and the fit was again determined. Data were statistically analyzed by paired and unpaired Student’s-t test (α=0.05). Results: Marginal and internal fit before ceramic application according to the coping manufacturing method showed significant differences only at CO (p < 0.001), with milled copings (137.98±16.71 μm) showing higher gap values than cast copings (112.86±8.57 μm). For cast copings, there were significant differences at MG (before 109.13±8.79 μm; after 102.78±7.18 μm) and CO (before 112.86±8.57 μm; after 104.07±10.63 μm) when comparing the fit before and after ceramic firing. For milled copings, there was significant difference only at AO (before 116.39±9.64 μm; after 108.54±9.26 μm). Conclusion: This study demonstrated that the coping fabrication method influenced the internal fit. Ceramic firing maintained or improved the fit of the metal-ceramic crowns. The marginal discrepancy of all restorations, before and after ceramic firing, can be considered clinically acceptable.

Evaluation of the peri-implant tissues in the esthetic zone with prefabricated titanium or zirconia abutments: A randomized controlled clinical trial with a minimum follow-up of 7 years

Statement of problemLong-term clinical studies are lacking on the influence of the type of abutment, titanium or zirconia, on peri-implant tissues. PurposeThe purpose of this randomized clinical trial was to evaluate peri-implant tissues with titanium or zirconia abutments. Material and methodsA total of 26 single-tooth implant-supported prostheses in 14 participants were analyzed. They received either a titanium abutment with a metal-ceramic crown (TAG) or a zirconia abutment with a ceramic crown (ZAG). Data were collected immediately, at 5 months, and at a minimum of 7 years after crown delivery. The success rate, plaque and bleeding indexes, bleeding on probing, white and pink esthetic scores, and the relationships of the gingival phenotype with the pink esthetic score were analyzed. Statistical analyses were conducted with the t test for paired and independent data (α=.05). ResultsThe mean follow-up time was 95.2 ±2.6 months, showing an implant success rate of 96.7%. No statistically significant differences were found between TAG and ZAG among the time intervals evaluated for plaque or bleeding indexes (P>.05). A statistically significant difference was found for peri-implant probing depths in the mid-buccal sites between the groups at all the time intervals evaluated (TAG, P=.008; ZAG, P=.021): TAG showed an increase between 5 months (3.65 ±0.93 mm) and over 7 years (4.47 ±1.32 mm); and ZAG showed a reduction (5 months=5.22 ±1.71 mm; over 7 years=4.25 ±1.28 mm) in values. For the pink (PES) and white esthetic score (WES), ZAG (PES: immediately=6.33 ±1.41; 5 months=7.44 ±1.81; over 7 years=8.25 ±1.03; WES: immediately=7.67 ±1.50; over 7 years=8.38 ±0.74) showed higher mean values than TAG (PES: immediately=5.94 ±2.35; 5 months=6.53 ±2.15; over 7 years=7.44 ±1.81; WES: immediately=7.00 ±1.17; over 7 years=8.35 ±1.27) (P<.05). Statistically significant differences were found for gingival phenotype and for PES in TAG (P=.031), and the participants with thick phenotype showed higher PES in the 3 time intervals studied. ConclusionsZirconia abutments exhibited better results than titanium abutments in terms of the peri-implant tissues. Moreover, in those with a thin phenotype, zirconia provided improved gingival esthetics.

ASSESSMENT OF ANGULAR DEVIATIONS OF THE VERTICAL SURFACES OF TEETH STUMPS OBTAINED DURING ODONTOPREPARATION FOR FIXED ORTHOPEDIC STRUCTURES (METAL-CERAMIC AND SOLID CROWNS)

Relevance. Odontoreparation is fundamental to ensure the functional efficiency, high aesthetics and durability of fixed prostheses. At present, with fixed prosthetics of defects in hard tissues of teeth and dentition, various types of artificial crowns are widely used [1][2].Purpose of the study: to determine the angular deviations of the vertical surfaces of molars, prepared by students of the 3rd year. Based on the data obtained, calculate the average value for the group and identify which surfaces of the stump are most prone to errors during odontopreparation.Materials and methods. Frasaco® phantom teeth (mandibular molars) were used as research materials. Preparation for metal-ceramic crowns was carried out according to the traditional method by thirteen third-year students of the Samara State Medical University of the Ministry of Health of Russia. In this work, 6° was taken as the optimal angle of convergence of the vertical walls (3° on each of the two opposite surfaces). During the preparation, a fissure bur d = 1.6 mm was used.Conclusion. The average time spent on preparation is quite long, which indicates an insufficient level of manual skills. The revealed phenomena of wall divergence also indicate that the preparation skills are insufficient. In addition, divergence was found mainly on the distal surface, which is explained by more difficult access and limited visibility of the prepared surface.

ASSESSMENT OF ANGULAR DEVIATIONS OF THE VERTICAL SURFACES OF TEETH STUMPS OBTAINED DURING ODONTOPREPARATION FOR FIXED ORTHOPEDIC STRUCTURES (METAL-CERAMIC AND SOLID CROWNS)

Relevance . Odontoreparation is fundamental to ensure the functional efficiency, high aesthetics and durability of fixed prostheses. At present, with fixed prosthetics of defects in hard tissues of teeth and dentition, various types of artificial crowns are widely used [1, 2]. Purpose of the study : to determine the angular deviations of the vertical surfaces of molars, prepared by students of the 3rd year. Based on the data obtained, calculate the average value for the group and identify which surfaces of the stump are most prone to errors during odontopreparation. Materials and methods. Frasaco ® phantom teeth (mandibular molars) were used as research materials. Preparation for metal-ceramic crowns was carried out according to the traditional method by thirteen third-year students of the Samara State Medical University of the Ministry of Health of Russia. In this work, 6° was taken as the optimal angle of convergence of the vertical walls (3° on each of the two opposite surfaces). During the preparation, a fissure bur d = 1.6 mm was used. Conclusion. The average time spent on preparation is quite long, which indicates an insufficient level of manual skills. The revealed phenomena of wall divergence also indicate that the preparation skills are insufficient. In addition, divergence was found mainly on the distal surface, which is explained by more difficult access and limited visibility of the prepared surface.

Effect of Material Selection and Different Fabrication Techniques on Marginal and Internal Fit of Metal Ceramic and All Ceramic Crowns (In vivo and In vitro study)

Purpose: Assess the effect of material selection as well as different fabrication techniques of metal ceramic (MC) and all ceramic crowns on their clinical outcomes, marginal and internal fit. Materials and methods: In vivo study(I); twenty- eight patients were provided with twenty-eight crowns restoring mandibular first molar tooth. Patients were distributed into 2 groups and 2 subgroups according to different materials and fabrication techniques: fourteen patients received MC crowns, group (I); seven patients received crowns with conventional casting of Co-Cr copings, subgroup (A) and seven patients received crowns with direct milling of Co-Cr copings, subgroup (B). Fourteen patients received IPS e.max press crowns, group (II); seven patients received crowns with conventional wax pattern, subgroup (A) and seven patients received crowns with 3D printing resin pattern, subgroup (B). The survival rate of these crowns was evaluated and statistically analyzed. In vitro study(II); one machined die was prepared to simulate crown preparation of mandibular first molar tooth. 60 crowns were constructed on die and divided into 2 groups (30 samples each) and 2 subgroups (15 samples each) according to different materials and fabrication techniques similar to in vivo study. Replica technique obtained to measure marginal and internal fit using Digital microscope. Results: The survival rate of MC and press crowns was 98% and 60% respectively. Press crowns and digital technique showed superior marginal and internal fit than MC crowns and conventional technique respectively. Conclusions: Material type and fabrication technique of MC and all ceramic crowns influence their clinical outcome, marginal and internal fit.

Endodontically treated teeth with custom cast post and core and metal ceramic crowns restoration: A case report

There are various post systems and materials available which is used for restoration of fractured tooth structure of endodontically treated teeth. It is a great challenge for the dentist to decide on which system and material to use for restoration of teeth. The reason to use post is to retain the core that holds the definitive prosthesis. Cast metal post and cores are widely used for restoring endodontically treated teeth with extensive loss of tooth structure and to restore with metal-ceramic crowns. The following case report depicts the restoration of fractured teeth after using custom cast post followed by metal-ceramic crowns.

An Ultrastructural Study on the Effect of High Temperatures on Teeth and Restorative Materials That Aids in the Identification of Human Remains

Introduction In most disasters, teeth are the only means of positive identification of an otherwise unrecognizable body, as there has been tremendous increase in the use of dental restorations that have different resistance to prolonged high temperature which is an important aid in identifying burned victims. Application of SEM/EDS in forensics was found useful in areas where there is a need for good imaging with high magnification combined with elemental analysis. The objective of this study was to analyze incineration effects on teeth and restorative materials using SEM/EDS. Materials and Method. 128 extracted teeth were collected, 96 were restored with silver amalgam, composite, and GIC of 32 each, and crown preparation was done in 32 teeth for which metal ceramic crowns were prepared. These teeth were subjected to 4 different temperatures (500°C, 700°C, 900°C, and 1100°C) for 20 minutes, and they were analyzed macroscopically and by using SEM for the changes subsequent to their exposure to such high temperatures. Results All the restorations which were very difficult to identify by naked eye were identified with the help of SEM/EDS. Conclusion Elemental analysis of the specific restorative material proves to be an essential tool for the forensic odontologist.

One Year Clinical Evaluation of Milled BioHPP Polyetheretherketone (PEEK)-Based versus Metal Ceramic Single Crowns (Randomized Controlled Clinical Trial)

Objective: To evaluate the clinical behavior of milled BioHPP PEEK copings veneered with Visio.lign composite resin in comparison with metal copings veneered with feldspathic porcelain as single posterior crowns. Material and Methods: Twenty Four full coverage posterior crowns were fabricated for endodontically treated molars divided into 2 groups according to the material used. Twelve milled BioHPP PEEK-based crowns (Group 1) and Twelve Porcelain Fused to Metal (PFM) crowns (Group 2). The preparations were standardized with an equi-gingival, deep chamfer finish line for all teeth. BioHPP PEEK and metal copings were fabricated by CAD/CAM technology and lost wax technique respectively. These coping were veneered according to manufactures instructions either by special composite resin or low fusing glass ceramic respectively. The restorations were cemented then clinical evaluation of these crowns was assessed regarding mechanical failure, marginal integrity and patient satisfaction every two months for one year. Results: Although two PEEK crowns were fractured, both PEEK and PFM crowns showed similar fracture (mechanical failure) and marginal integrity without significant difference (P &gt; 0.05). BioHPP PEEK-based crowns showed statistically significantly lower patient satisfaction than PFM crowns after six months (P-value = 0.013, Effect size = 1.157) but all the patients were generally satisfied. Conclusion: BioHPP PEEK-based crowns showed clinically similar and accepted mechanical behavior and marginal integrity but less patient’s satisfaction than PFM crowns after six months. So BioHPP PEEK-based crowns may be used as an alternative tooth-colored metal-free fixed restoration for one year. Keywords BioHPP; Metal ceramic; Patient satisfaction; PEEK; PFM.

ПЕРСПЕКТИВЫ ИЗГОТОВЛЕНИЯ КАРКАСОВ МЕТАЛЛОКЕРАМИЧЕСКИХ КОНСТРУКЦИЙ ЗУБНЫХ ПРОТЕЗОВ МЕТОДОМ СЕЛЕКТИВНОГО ЛАЗЕРНОГО СПЕКАНИЯ

The article presents the results of evaluating the prototyping of metal-ceramic structures made by casting and selective laser sintering. To achieve this goal, 27 patients with fabricated metal-ceramic crowns and bridgeworks were examined. Two study groups were created. The first group included 14 patients for whom dental prosthesis frameworks were made by casting. The second group consisted of 13 people, for whom the frames of dentures were made by the method of selective laser sintering. The analysis of clinical effectiveness was carried out according to the following criteria: 1- precision of the felling of prosthesis frame to solid tissues of abutment teeth; 2- the condition of the marginal periodontium; 3- the integrity of the ceramic cladding. The results of the study showed that the precision to solid tooth tissues of metal-ceramic dental prostheses made by laser selective sintering is higher than of frames made by casting. In accordance to the second criteria the best results were also shown by the participants of the second group. No chipping of the ceramic veneer from the metal-ceramic denture frameworks made by laser selective sintering was found. Thus, dentures which frameworks are made by the method of selective laser sintering are characterized by a higher objective assessment of their precision to the solid tissues of the abutment teeth. Lesions of the marginal periodontium both inflammatory and dystrophic were less in the participants of the second group. The frequency of defects in the coating of metal-ceramic dentures was significantly lower in the case of fabrication frameworks by laser selective sintering.

Comparative Evaluation of Marginal and Internal Fit of Anatomic and Nonanatomic Metal Frameworks Fabricated by Selective Laser Sintering

For teeth restoring single metal-ceramic crowns were the gold-standard for many years. Selective laser sintering is a new technology which can provide accurate complex-shaped frameworks for dental restorations, layer-by-layer, according to a three-dimensional computer model, using metal powder. An important factor for long term success of fixed prostheses is the marginal and internal adaptation. The aim of the study was to evaluate the effect of framework design and design of tooth preparation on marginal and internal fit of laser-sintered frameworks. Two maxillary first molars where prepared with two different kind of marginal limits. Two different framework designs were constructed for each: model 1 – a coping with a constant framework thickness of 0.6 mm and model 2 - an anatomically modified shaped cusp supporting framework with a constant veneering thickness. The mean marginal gap values were between 37 and 95 μm, the means for the axial region were between 47 and 70 μm and for the occlusal region between 67 and 147 μm. Copings produced by selective laser sintering using CAD/CAM technologies demonstrate acceptable marginal and internal fit in the range of 47 to 120 μm, with better results in case of anatomically-reduced frameworks.

Influence of collar height of definitive restoration and type of luting cement on the amount of residual cement in implant restorations: A clinical study

Statement of problemResidual cement in the peri-implant sulcus may cause peri-implant mucositis, which can lead to peri-implantitis. Clinical studies comparing the role of the collar height of the definitive restoration and the type of cement used for luting the prosthesis in the amount of residual cement are lacking. PurposeThe purpose of this clinical study was to determine the volume of residual cement left undetected in the peri-implant sulcus by an implant prosthesis with 3 different collar heights and 3 luting cements. Material and methodsParticipants with single implants in the premolar region were divided into 3 groups of 10 according to the distance from the peri-implant soft tissue crest to the implant platform: group low collar (sulcus depth <2 mm), group medium collar (2-4 mm), and group high collar (>4 mm). A metal-ceramic crown with an occlusal opening was fabricated on a straight titanium abutment, which facilitated removal of the crown along with the abutment after cementation. The implant luting cements used were composite resin cement (RelyX U200), Type I glass ionomer cement (GC Gold Label 1), and zinc oxide noneugenol interim luting cement (RelyX Temp NE). The modified crown was cemented with 1 cement each during the impression, bisque evaluation, and definitive crown cementation appointments. The crown was retrieved, and the residual cement collected during each appointment. The measurements obtained were statistically analyzed with general linear model analysis followed by post hoc testing using the Bonferroni test (α=.05). ResultsMean volume of the residual excess cement (mm3) formed in group low collar was 0.33 ±0.17, 0.26 ±0.17, and 0.08 ±0.08 for subgroups Resin, GIC, and ZNE, respectively. In group medium collar, it was 1.18 ±0.31, 1.08 ±0.3, and 0.61 ±0.32; and in group high collar, it was 2.33 ±0.31, 2.1 ±0.74, and 1.31 ±0.56 for the same subgroup, respectively. There was a statistically significant difference in the formation of REC between the collar height groups (P<.001). Among the luting cements, zinc oxide noneugenol cement produced significantly lower residual cement compared with the other 2 cements, and there was no statistically significant difference between the glass ionomer and resin cements (P>.05). ConclusionsThe collar height of the definitive restoration and the type of luting cement play significant roles in the formation of residual cement in fixed implant-supported restorations.

IMMEDIATE IMPLANT PLACEMENT AT ANTERIOR MAXILLARY REGION

INTRODUCTION: Immediate dental implants have greatly reduced the treatment time and the number of surgical interventions. Recently it has been noted that this treatment modality can be used in aesthetically demanding cases especially the anterior maxilla. CASE REPORT: In the present case report a 24 year old male patient reported to our institution with fractured upper front teeth. After careful examination and treatment planning immediate implant treatment was initiated. The teeth were extracted atraumatically. We placed three implants into the extraction sockets. The prosthetic rehabilitation was done with metal ceramic crowns. CONCLUSION: It was found that the immediate implant therapy has several advantages such as reduced treatment length, preservation of soft and hard tissues surrounding the implant and reduced number of operations. Immediate implant treatment therefore has a great future in the treatment of aesthetic zones.

Orthopedic treatment with fixed dentures taking into account the distribution and causes of defects in dental hard tissues

The aim of this work was to analyze the causes of complications of orthopedic treatment of dentition defects with metal-ceramic crowns and non-removable metal-ceramic bridges. Materials and methods. A total of 140 patients aged 34 to 49 years were examined during the work, who underwent the production of both single metal-ceramic crowns and non-removable metal-ceramic bridges. All patients were divided into 2 groups (70 patients each): the first one included patients with vital abutment teeth, the second one – with depulped. The abutment teeth had a different functional state – they were filled, had wedge-shaped defects or increased abrasion. Results. Orthopedic treatment showed that the manufacture of solid metal-ceramic crowns on dental teeth, which were filled more than 1 year ago, led to complications in 18 of 35 (51.4 %) patients in this group, which is insignificantly (P ˃ 0.05) by 17.2 % less than with similar prosthetics on depulped teeth. Regarding the manufacture of bridges, the trend of more complications in prosthetics on devital teeth persists, because in group I we had 20 (57.7 %) patients with complications, and in group II – 29 (82.9 %) cases, which is significantly different at the level of P &lt; 0.05. In prosthetics of vital teeth, defects of hard tissues of which are replaced by filling material immediately before prosthetics, single crowns of complications occurred in 3 patients, i.e. in 8.6 %, which is insignificantly (P ˃ 0.05) less by 5.6 % than in group II where complications were found in 5 (14.2 %) people. Analysis of orthopedic treatment of patients with included defects of dentitions with metal-ceramic bridge prostheses revealed that when using filled teeth (filled for 1 year before prosthetics) in the case, when they were depulped, as abutment, complications were observed in 9 people, i.e. in 25.7 % of this group. This indicator insignificantly (P ˃ 0.05) exceeds the identical one from the first group (14.3 %) by 11.4 %, therefore, there is a tendency to reduce tooth resistance to negative external and internal factors, which has not acquired statistical significance. Conclusions. The study found that the frequency of complications that occur after prosthetics with fixed dentures depends on the condition of the tooth pulp, because the viable pulp provides metabolism, renewal of tooth cells and response to any damage. The need to replace fillings that were made more than 1 year ago to reduce the risk of secondary caries has been proven. Defects of hard tissues in the form of a wedge-shaped defect and the increased attrition do not increase frequency of complications in prosthetics by fixed dentures.

A Simple Technique to Repair Feldspathic Porcelain Chipping in Screw-retained Implant-supported Prosthesis: A Clinical Technique

This clinical technique report aimed to describe a composite resin repair technique performed in an implant-supported prosthesis. Veneering ceramic fracture or chipping is one of the most frequent clinical failures in dentistry. Therefore, the use of less time- and cost-consuming ceramic repair techniques is helpful in clinical practice. Briefly, to treat the ceramic surface, the glaze was removed at the margins of the fracture area, then, air-abrasion and acid-etching were performed. To promote chemical adhesion, a silane coupling agent and adhesive system were applied over the ceramic surface, and the composite resin was applied by incremental technique. Finally, the polish was performed. In conclusion, the applied composite resin repair of feldspathic porcelain chipping in implant-supported prosthesis was a simple, easy, affordable, and minimally invasive treatment. The causes of veneer materials failures in metal-ceramic crowns are considered a challenge for the dentist and a problem that displeases patients. Repairs are indicated to prevent cracks from spreading and to prevent the accumulation of biofilm on the damaged surface. Therefore, different repair protocols have been proposed to enhance the esthetic, functionality, and longevity of the implant-supported prosthesis. Additionally, the success of the clinical cases depends on the capability to identify ceramic failures and the ability to indicate/perform the correct repair protocol. Since the described repair technique of the fractured screw-retained implant-supported prosthesis was a simple, easy, affordable, and minimally invasive treatment, with excellent esthetic and masticatory results, it represents an interesting clinical option.

Three-year clinical performance of posterior monolithic zirconia single crowns

Statement of problemMonolithic zirconia has become widely used for single crowns, with the advantages of minimal tooth reduction and good esthetics. However, clinical studies evaluating the performance of and patient satisfaction with posterior monolithic zirconia crowns are sparse. PurposeThe purpose of this clinical study was to evaluate the clinical performance of and patient satisfaction with posterior monolithic zirconia crowns. Material and methodsWithin a prospective cohort study design, participants were recruited from a university dental clinic if they required 1 posterior monolithic zirconia crown. The clinical performance was evaluated at follow-up appointments 1, 2, and 3 years after insertion. Bleeding on probing and pocket probing depths for the crowned teeth were recorded. Overall patient satisfaction was measured by using a visual analog scale (VAS), and quality of life was measured by using the validated German version of the Oral Health Impact Profile 14 (OHIP-G14). Descriptive statistical methods were applied. Mean values were calculated and compared by using the paired t test (α=.05). ResultsThirty participants received a monolithic zirconia crown (14 premolars, 16 molars). One biologic complication (vertical root fracture) was identified at the 1-year follow-up. Three years after insertion, 22 participants could be examined, and the crowns were still in function. The gingival and the periodontal status of the crowned teeth had not changed significantly over the 3 years. After insertion, a significant improvement in patient satisfaction was measured up to 3 years ConclusionsPosterior monolithic zirconia crowns led to enhanced patient satisfaction up to 3 years after insertion. They provided good middle-term success and offered a promising alternative to conventional metal-ceramic crowns.

ANALYSIS OF ANGULAR DEVIATIONS IN ODONTOPREPARATION OF TEETH FOR ORTHOPEDIC STRUCTURES

Odontoreparation is fundamental to ensure the functional efficiency, high aesthetics and durability of fixed prostheses. At present, with fixed prosthetics of defects in hard tissues of teeth and dentition, various types of artificial crowns are widely used [1, 2]. Purpose of the study: to determine the angular deviations of the vertical surfaces of molars, prepared by students of the 3rd year. Based on the data obtained, calculate the average value for the group and identify which surfaces of the stump are most prone to errors during odontopreparation. Materials and methods. Frasaco® phantom teeth (mandibular molars) were used as research materials. Preparation for metal-ceramic crowns was carried out according to the traditional method by thirteen third-year students of the Samara State Medical University of the Ministry of Health of Russia. In this work, 6° was taken as the optimal angle of convergence of the vertical walls (3° on each of the two opposite surfaces). During the preparation, a fissure bur d = 1,6 mm was used. Conclusion. The average time spent on preparation is quite long, which indicates an insufficient level of manual skills. The revealed phenomena of wall divergence also indicate that the preparation skills are insufficient. In addition, divergence was found mainly on the distal surface, which is explained by more difficult access and limited visibility of the prepared surface.

Accuracy evaluation of fixed prosthetic constructions made by milling and printing technologies and the influence of temperature changes

The aim of this study is to evaluate the internal and external fit accuracy of fixed metal-ceramic prosthetic constructions made by milling and printing technologies and the influence of temperature changes on this accuracy. An acrylic resin tooth was prepared according to the standard guidelines for a metal-ceramic crown. A standard intraoral silicone impression was taken and a stone model was prepared. The stone model was scanned by an extraoral digital scanner and a digital copy of the prosthetic field was created. The digital copy was used to create a digital prototype of the future metal substructure for the metal-ceramic crown. Using the same data, the metal substructure was formed once by milling technology, and once by 3D-printing technology. The internal surface of both samples was measured. The stone model preparation surface was also measured. All data were compared to the digital prototype. According to the standard technology, a dental technician applied ceramic material, by hand as usual, in layers and the constructions were sintered. After the thermal procedure, once again the substructure’s internal surface was measured and compared with the previous data. The constructions were finished by glazing by the dental technician applying the last layer ceramic and sintering it. The construction’s internal surface was again measured and the data obtained were compared with the previous data. Conclusion about the influence of the temperature changes caused by the sintering process on the metal substructures was made using the data acquired by all the measurements made between the different stages. The difference in the internal fit of the constructions made by the milling and the 3D-printing technology will not affect to crown’s ergonomics. The quality of the internal fit for the construction made by milling technology is better than this made by 3D-printing technology. Unnoticeable changes in the internal surface were found after the temperature changes caused by the process of sintering for both types of constructions. Both types of technologies could be used to produce high quality accurate metal substructures for the needs of the fixed prosthetic dental medicine. The temperature changes caused by the sintering process during the standard metal-ceramic technology have a small influence to the construction’s internal fit.

A Comparative Study to Evaluate the Marginal Fit and Fracture Resistance of Peek Material with two Other Restorative Crowns Fabricated Using Cad – Cam Technology – An In Vitro Study

Aim : To compare and evaluate the marginal fit and fracture resistance of PEEK material with two otherrestorative crowns namely – DMLS (metal-ceramic – cobalt-chromium) &amp; All ceramicMaterials and methods: 35 artificial crownsn were fabricated. 20 samples were earmarked for evaluationof marginal fit using stereomicroscope and 15 samples were intended for fracture resistance. Materials usedfor fabrication of crowns were metal ceramic, all-ceramic, and PEEK materialsResults : There was no statistically significant difference between these materials (P &gt; 0.05). than fractureresistances were compared.Conclusion : The marginal fit of all ceramic-zirconia crowns was higher than that of the PEEK and DMLSmetal-ceramic crowns and Fracture resistance of DMLS - metal-ceramic crowns was higher than the fractureresistance of the PEEK and all-ceramic- zirconia restorative crowns.