The Use of Hall's Technique Preformed Metal Crown (HTPMC) by Pediatric Dentists in Malaysia.

INTRODUCTION: Hall's technique preformed metal crown (HTPMC) has been used widely by pediatric dentists in developed countries as a new approach for managing decayed primary molars without local anesthesia, caries removal, and tooth preparation. Currently, inadequate information is available regarding the implementation of this technique (HTPMC) in Malaysia. This study is aimed at evaluating the implementation of HTPMC by Malaysia's pediatric dentists and identify the co-occurrence frequencies of the HTPMC implementation with the respondents' demographic profile. MATERIALS AND METHODS: A cross-sectional questionnaire-based research was conducted among 65 pediatric dentists in Malaysia. Online questionnaires were distributed to the pediatric dentists employed at public hospitals (MOH) and universities in Malaysia. RESULT: It was found that over half of the respondents (65.6%) employed HTPMC. The analysis of the co-occurrence network frequency revealed that a high frequency of female pediatric dentists who were within the age group of 31-40 years old had fulfilled their postgraduation overseas and was employed in the university mainly applied HTPMC. CONCLUSION: The application of HTPMC among respondent pediatric dentists in Malaysia was high. However, most respondents considered HTPMC a treatment option only to manage carious primary molar rather than a treatment of choice.

Assessment of Peri-Implant Soft Tissues Conditions around Short and Ultra-Short Implant-Supported Single Crowns: A 3-Year Retrospective Study on Periodontally Healthy Patients and Patients with a History of Periodontal Disease.

The aim of this retrospective study was to evaluate implant survival, marginal bone loss and peri-implant complications in 326 short and ultra-short implants. Implants were placed in the maxillary and mandibular posterior regions of 140 patients with (PP) and without (NPP) a history of periodontal disease. Clinical and radiographic examinations were performed at 3-year recall appointments. The 8.0, 6.0 and 5.0 mm-length implants placed in PP and NPP were respectively 43.75% and 38.46%, 35.10% and 34.19%, 21.15% and 27.35%; 325 implants (one early failure) were rehabilitated with single crowns in 139 patients. Overall implant survival after 3 years of follow-up was 97.55%, 98.08% and 96.61% for PP and NPP (p = 0.46). Crestal bone level variations were not statistically different among PP and NPP; 15.41% of implants presented signs of mucositis, 14.71% and 16.67% in PP and NPP (p = 0.64). Setting the threshold for bone loss at 2 mm after 36 months, peri-implantitis prevalence was 2.2%, 1.96% and 2.63% in PP and NPP (p = 0.7). Overall implant success was 82.39%, 83.33% and 80.7% for PP and NPP (p = 0.55). Short-term outcomes suggest that short and ultra-short locking-taper implants can successfully be restored with single crowns in the posterior jaws both in PP and NPP.

Five year evaluation of the complications observed in porcelain fused to metal (PFM) crowns placed at a university hospital.

OBJECTIVE: To determine the frequency of complications in crowns cemented over a 5-year period in a tertiary care hospital and also to report the survival of these crowns. METHODS: The retrospective cross-sectional study was conducted at the Aga Khan University Hospital, Karachi, from March 2017 to March 2018 and comprised porcelain fused-to-metal crowns placed on the anterior or posterior teeth that were fabricated at the institutional laboratory and were placed in institutional dental clinics in the preceding 5 years. Porcelain-fused to-metal The crowns were clinically and radio-graphically evaluated in a duration of two months for presence/absence of complications. Factors associated with the failure of the crowns, their survival and the impact of covariates, like gender, flossing and bruxism, on the survival time were determined. Data was analysed using SPSS 22. RESULTS: There were 150 crowns related to 107 patients who had a mean age of 45.0±11.4 years. The most common complication observed was open proximal contacts 9(6%) followed by de-cementation 8(5.3%), porcelain chipping 9(6%) and abutment fracture 2(1.3%). The 5-year survival rate of the crowns was 127(84.7%). The mean follow-up time was 57.2±1.0 months. Overall, year-wise survival of PFM crowns for one year till five years was 147 (98%), 144 (96%), 135 (90%), 130 (86%) and 119 (79%) respectively. CONCLUSIONS: The porcelain-fused-to-metal crowns had a high 5-year survival rate. Open proximal contacts represented the most common complication.

Indications for root canal treatment in a Swedish county dental service: patient- and tooth-specific characteristics.

AIM: To study patient- and tooth-specific characteristics of teeth indicated for root canal treatment, in the public dental service of the county of Västra Götaland, Sweden. METHODOLOGY: During a designated 8-week period, general dental practitioners working at 20 different public dental clinics consecutively registered indications for undertaking root canal treatment. The patients' subjective level of pain was also registered (visual analogue scale) at the very first appointment. The following information was retrieved from computerized dental records and radiographs: gender, age, number of remaining teeth, tooth group, previous restoration, number of restored surfaces, dental caries and tooth substance loss. Gender and age were compared using both descriptive and analytical statistics. RESULTS: The material comprised 243 teeth in 243 patients: 128 (52.7%) women and 115 (47.3%) men, mean age 48.3 years. Molar teeth predominated (47.7%). Most of the teeth (83.5%) had previously been restored and exhibited significant loss of tooth substance, more than a third of the crown (71.3%). Dental caries was present in 127 teeth (62.9%). Dental trauma was implicated in only seven cases (2.9%). Initial treatment was frequently undertaken at an emergency visit, for relief of symptoms (64.9%). The most commonly registered indication was pulpal necrosis with apical periodontitis (38.1%), followed by pulpitis (37.7%). Retreatment of a root filled tooth was reported in 18 teeth (7.4%). CONCLUSIONS: In the general Public Dental Service of Sweden, root canal treatment is most frequently undertaken in molars. The primary indication is relief of symptoms. Retreatment of root filled teeth is uncommon.

Influência da presença e do tipo de retentor intrarradicular no comportamento em fadiga de incisivos centrais restaurados com coroas totais / Influence of the presence and type of post-and-core on the fatigue behavior of crowned central incisors

Este estudo avalia a influência da presença e tipo de pinos e núcleos na sobrevivência à fadiga de incisivos centrais restaurados com coroas totais. As coroas de 69 incisivos bovinos foram cortadas e as raízes tratadas endodonticamente. As raízes foram distribuídas aleatoriamente em três grupos (n = 23): núcleo de resina composta (NRC), núcleo de resina composta retido por pino de fibra de vidro (PFV) e núcleo metálico fundido (NMF). Todos receberam preparo de coroa total com férula de 2 mm, e então, uma coroa de cerâmica reforçada com leucita foi adesivamente cimentada. Três amostras de cada grupo foram testadas para determinação da carga máxima até a falha. As amostras restantes foram carregadas pelo teste acelerado de fadiga stepwise stress até a fratura ou suspensão após o término de 1,5 x 106 ciclos. A carga e o degrau em que cada espécime falhou foram analisadas pela estatística de Kaplan-Meier e Mantel-Cox (Log Rank test), seguidas por comparação múltipla aos pares, com nível de significância de 5%. O modo de falha foi analisado com estéreomicrocópio. Não houve diferença estatística entre os tratamentos quanto à carga (Mantel-Cox Log-Rank test for trend, X2=0,015, df=1, p=0,901), nem para o número de ciclos (Mantel-Cox Log-Rank test for trend, X2 =3,171, df=1, p=0,995). O modo de falha predominante foi a trinca da coroa. Fratura obliqua da raiz só foi observado nos grupos retidos por pinos. Nos incisivos tratados endodonticamente com férula de 2 mm, a presença e o tipo de pino e núcleo não influenciaram na sobrevida em fadiga. Fraturas não restauráveis ocorreram somente em dentes restaurados com pinos(AU)

This study evaluates the influence of presence and type of post-and-core systems on fatigue survival of non-vital central incisors restored with all-ceramic crowns. The crowns of 69 bovine incisors were cut and endodontically treated. The roots were randomly assigned into three groups (n=23): composite resin build-up (NRC), glass fiber post-retained-composite build-up (PFV) and cast post-and-core (NMF). All specimens received crown preparation with a 2 mm ferrule, and then a leucite-reinforced ceramic crown was adhesively cemented. Three samples from each group were tested for the determination of the maximum load to failure. The remaining samples were loaded by the accelerated fatigue stepwise stress test until fracture or suspension after the end of 1.5 x 106 cycles. The load and the step on which each specimen failed were analyzed by the Kaplan-Meier and Mantel-Cox (Log Rank test) statistics, followed by multiple paired comparisons, with a significance level of 5%. The failure mode was analyzed with stereomicroscope. There was no statistically significant difference between the treatments (Mantel-Cox Log-Rank test for trend, X2=0.015, df=1, p=0.901), nor for the number of cycles (Mantel-Cox Log-Rank test for trend, X2=3.171, df=1, p=0.995). The predominant failure mode was the crown crack. Oblique root fracture was observed only in groups retained by posts. The presence and type of post system did not influence the fatigue survival of the endodontically treated incisors with a 2 mm ferrule. Non-restorable fractures only occurred on teeth restored with post(AU)

The ultimate guide to restoration longevity in England and Wales. Part 8: Canine teeth: time to next intervention and to extraction of the restored tooth.

Aim: It is the aim of this paper to present data on the survival of restorations in canine teeth by analysis of the time to re-intervention on the restorations and time to extraction of the restored tooth, and to discuss the factors which may influence this. Methods: A data set was established, consisting of General Dental Services (GDS) patients, this being obtained from all records for adults (aged 18 or over at date of acceptance) in the GDS of England and Wales between 1990 and 2006. The data consist of items obtained from the payment claims submitted by GDS dentists to the Dental Practice Board (DPB) in Eastbourne, Sussex, UK. This study examined the recorded intervals between placing a restoration in a canine tooth and re-intervention on the tooth, and the time to extraction of the restored tooth. Results: Data for more than three million different patients and more than 25 million courses of treatment were included in the analysis. Included were all records for adults (aged 18 or over at date of acceptance). Overall, 1,232,052 restorations involving canine teeth were included in the analysis. With regard to time to re-intervention, 33% of restorations had survived at 15 years, and with regard to time to extraction of the restored tooth, cumulative survival was 78% at 15 years. Veneers and crowns performed best in terms of time to re-intervention, but crowns performed worst when time to extraction was analysed. Conclusions: Overall, crowns and porcelain veneers placed on canine teeth perform best to re-intervention after 15 years, but crowns perform worst when the time to extraction of the restored tooth is examined and veneers perform best, with a 20 percentage point difference in cumulative survival at fifteen years between crowns and the best performing restoration in the under-40 year age group, this effect being accentuated in the over-40 year age group. Other factors influencing restoration longevity in canine teeth include: patient age, dentist age and the patient's annual need for dental treatment.

Prospective Randomized Clinical Trial of Primary Molar Crowns: 24-Month Results.

Purpose: The purpose of this study was to evaluate the clinical success of a new primary zirconia molar crown compared with stainless steel crowns (SSCs). Methods: This randomized, controlled clinical trial was designed as a split-mouth study. Fifty three- to seven-year-old children were recruited to provide a total of 50 pairs of teeth requiring primary molar crowns, with each participant receiving a SSC and zirconia crown. Restorations were evaluated at six-month, 12-month, and 24-month recall appointments examining the following criteria: gingival health; estimate of extent the crown was high in occlusion; surface roughness; staining on crown surface; wear of opposing arch tooth; color match; anatomic form; marginal integrity; marginal discoloration; proximal contact area; secondary caries at crown margin; and parent/guardian satisfaction with crown appearance. Results: The 24-month follow-up included 39 patients (78 percent). Seventy crowns (70 percent) were evaluated; of the 36 zirconia crowns and 34 SSCs, there were no failures at the 24-month evaluation. The only significant difference in the parameters evaluated was in parental satisfaction with the zirconia crown preference (P<0.05). Conclusion: Current 24-month results indicate that zirconia primary molar crowns perform similarly to an established stainless steel crown for restoration of primary molar teeth.

An analysis of the timing and materials associated with pulp disease following restorative dental treatment.

AIM: To assess whether the timing of pulp disease after tooth restoration was associated with type of restorative dental material used, extent of the restoration or tooth type. METHODOLOGY: A comprehensive search and analysis of data using the Titanium Oral Health Management software program at The Oral Health Centre of Western Australia were performed to correlate procedural codes for teeth that had restorations placed and subsequently developed pulp disease requiring endodontic treatment or extraction from 1st January 2009 to 31st December 2013. Manual analysis of paper and/or electronic patient record cards was also performed. Data collected included restoration type, restored tooth surfaces, tooth type and the dates of restoration and subsequent endodontic intervention or extraction. RESULTS: Of 330 teeth that met the inclusion criteria, 84 (26%) had composite resin restorations, 80 (24%) had amalgams, 119 (36%) had glass-ionomer cement (GICs), and 47 (14%) had crowns. The average time between restoration and further intervention was 330 days with a range from 3 to 1775 days (approximately 5 years). Teeth restored with crowns or five-surface restorations were significantly more likely to require earlier intervention than other restorations. Premolar and anterior teeth were also more likely to require earlier intervention. CONCLUSIONS: Teeth that developed pulp disease requiring further intervention that were restored with crowns and five-surface GIC developed the disease sooner than teeth that were restored with amalgam or composite. In teeth with five-surface restorations that developed pulp disease requiring further intervention, premolar and anterior teeth developed the pulp disease sooner than molars.

A practice based longevity study on single-unit crowns.

OBJECTIVES: This retrospective longitudinal study aimed to assess the longevity of single unit crowns placed by several dentists and to investigate risk factors associated with crown failures. METHODS: From patient files, longevity of 3404 full crown restorations placed in 1557 patients by 8 Dutch dentists between 1996 and 2011 were analyzed. Annual failure rates (AFRs) were calculated and variables associated with failure (success and survival of crowns) were assessed by multivariate Cox-regressions analysis with shared frailty for patients. RESULTS: Most of crowns were PFM (63.8%) placed in molars (58.1%) and non endodontically treated teeth (65.4%). The observation time of restorations varied from 3 weeks to 11 years with a mean of 7 years, resulting in a mean AFR at 11 years of 2.1% and 0.7% for success and survival of crowns, respectively. Among dentists a relevant variation for type of interventions was observed with AFR varying between 1.2% and 3.5%. The most significant risk factor for failure of crowns was the presence of an endodontic treatment, resulting in Hazard ratios of 1.31 for success [95%CI 1.07-1.61] and 1.89 [95%CI 1.35-2.65] for survival of crowns. Tooth type, tooth position (jaw) and gender showed also a significant influence on success of crowns. For survival, increase in patients' age results in a higher risk for failure. CONCLUSIONS: Overall, crowns placed by a selected group of dentist showed a good to acceptable success and survival rates, mainly dependent from the practice. The presence of an endodontically treated tooth was a significant risk factor leading to more failures.

Zirconia-based versus metal-based single crowns veneered with overpressing ceramic for restoration of posterior endodontically treated teeth: 5-year results of a randomized controlled clinical study.

OBJECTIVES: The aim of this 5-year randomized controlled trial was to compare the longevity and clinical behavior of single posterior crowns made with pressable ceramic on zirconia and on metal frameworks, and if failures occur, to delineate the contributing factors. METHODS: 72 patients, who needed the covering of at least a molar and/or premolar, were included in the study. All teeth were endodontically treated, with absence of periapical lesion or active periodontitis. Ninety single crowns were made with zirconia or metal framework and covered with pressable veneering ceramics. Two independent examiners assessed the survival of restorations at 6 months, 1-4 and 5 years after restoration placement including periapical radiographs, intraoral photographs, and USPHS modified criteria. The statistical analyses were performed with the Kaplan-Meier method. RESULTS: One core fracture occurred in Zircad/Zirpress crowns and one metal ceramic crown was lost for root fracture. Chipping fracture of the veneering ceramic was detected in 2 metal-ceramic crowns and in 3 zirconia-based crowns. The Estimate Cumulative Survival (ECS) and the Estimate Cumulative Success (ECSs) with standard deviation (SE) were respectively 97,73±2,19 and 92,64±4,14 for zirconia-based crowns whereas 97,44±2,39 and 91,11±4,27 for porcelain fused to metal crowns. CONCLUSIONS: The present randomized controlled trial shows that the survival of zirconia-based and metal-based single crowns is similar over a follow-up period of 5 years. No significant differences in esthetic, functional and biological outcomes were demonstrated between the two groups. The main failure mode was the chipping fracture of the veneering ceramic in both materials. Study number on ClinicalTrial.gov NCT02758457. CLINICAL SIGNIFICANCE: According to the results of this clinical study, zirconia-based rehabilitations with overpressing veneering technique represent a valid alternative to metal-based for posterior single crown restorations.

A Cross-Sectional Survey on Reasons for Initial Placement and Replacement of Single Crowns.

This cross-sectional survey investigated the reasons for placement and replacement of single crowns, the type of materials selected for initial placement and evaluated their longevity. Information was collected over 19 months period using a questionnaire focusing on the principal reasons for the placement and replacement of crowns, selected material type and the age of the crowns at the time of replacement. A total of 842 single crowns were evaluated in 476 patients. Of the 842 crowns, 472 (56%) were initial placements and 370 (44%) replacements. The main reason for placement of first single crowns was related to endodontic problems (26.5%). Metal-ceramic was indicated significantly more frequent (88.9%; p⟨0.01) than other materials for the placement and replacement of single crowns. The median age of the replaced crowns was 6 years.

Repair restorations: Questionnaire survey among dentists in the Canton of Zurich, Switzerland.

The aim of this study was to carry out a representative survey on the implementation of and experience with repairs of single-tooth restorations among dentists in the Canton of Zurich, Switzerland. An anonymous questionnaire was sent to all 1,411 dentists registered in the Canton of Zurich; 38.9% of the delivered questionnaires were returned and 35.3% could be evaluated. The statistical analysis comprised Kendall’s rank correlation coefficient (tau), Wilcoxon signed-rank tests, and Kruskal-Wallis tests. The level of significance was set at p≤0.05. Repair restorations are frequently made (composite: 98.5%, ceramic: 88.9%, crowns: 86.5%, metal: 54.6%, amalgam: 51.5%). Main indications for repairs were the partial loss of an existing restoration or of the adjacent dental hard substance, while restoration failures due to secondary caries were repaired to a lesser extent. The decision to repair is largely dependent on the size of the defect (90%), the size of the original restoration (63%), and the material of the failed restoration (84%). Repair restorations are most frequently made with composite following adequate conditioning of the repair surface. A majority of the dentists rate the lifespan of repair restorations as reduced in comparison with newly made restorations. In summary, repairs of defective single-tooth restorations are frequently performed by dentists in the Canton of Zurich, Switzerland, and constitute a well-established treatment procedure.

Ten-year survival and complication rates of lithium-disilicate (Empress 2) tooth-supported crowns, implant-supported crowns, and fixed dental prostheses.

OBJECTIVES: To prospectively evaluate the clinical long-term outcome of tooth-supported crowns (SCs), implant-supported crowns (ISCs), and fixed dental prostheses (FDPs) made of a lithium-disilicate glass-ceramic framework material (IPS Empress 2). MATERIALS AND METHODS: Between 1997 and 1999, a total of 184 restorations (106 SCs, 32 ISCs, 33 FDPs, and 13 diverse restorations) were placed in 73 patients. Kaplan-Meier estimation was applied for survival and chipping-free rates. Inter-group comparison of both rates was realized by a log rank test and a 2×2 contingency table. Also, SCs and FDPs were compared regarding adhesive vs. conventional cementation, and anterior vs. posterior positioning, for impact on survival. RESULTS: Due to 14 dropouts (34 restorations) and reasonable exclusion of 19 other restorations, the final dataset included: i) 87 SCs [37 patients, mean observation time 11.4 (±3.8)years]; ii) 17 ISCs [12 patients, mean observation time 13.3 (±2.3)years; and iii) 27 FDPs [19 patients, mean observation time 8.9 (±5.4)years]. The 10-year survival rate/chipping-free rate for SCs were 86.1%/83.4%, for ISCs 93.8%/94.1%, and for FDPs were 51.9%/90.8%. Both ISCs and SCs had a significantly higher survival than FDPs (ISCs vs. FDPs: both tests p=0.001; SCs vs. FDPs: p=0.001 and p=0.005). Differences in the chipping-free rates did not reach significance. Also, neither the cementation mode nor positioning of the restoration had an impact on survival. CONCLUSIONS: SCs had a slightly lower outcome than can generally be expected from single crowns. In contrast, ICSs had a favorable outcome and the FDPs predominantly failed. CLINICAL SIGNIFICANCE: The practitioner's choice of dental materials is based (at best) on long-term experience. The present 10-year results are based on comprehensive data analyses and show the high potential of lithium-disilicate as a reliable material, especially for single-unit restoration.

Estado gingival de dientes temporales con y sin restauración de coronas de acero en niños de 3 a 9 años / Gingival Condition around the Temporary Teeth with and without Steel Crown Restorations in 3-to-9 Year-Old Children

Antecedentes: Con las coronas de acero es posible conservar los dientes temporales hasta su exfoliación fisiológica; sin embargo, en la literatura existe controversia con respecto al comportamiento del tejido gingival de los dientes restaurados con coronas de acero. Propósito: /Analizar el estado gingival de dientes temporales con restauración de coronas de acero y sin esta en niños de 3 a 9 años de edad atendidos en las clínicas odontológicas de la Pontificia Universidad Javeriana, en Bogotá, entre 2013 y 2014. Métodos: Se realizó un estudio descriptivo de corte transversal. Se observaron 110 dientes temporales restaurados con corona de acero y sus antagonistas sin corona de acero. Se analizaron los índices gingival y de biopelíeula, la adaptación clínica de las coronas de acero y la presencia o ausencia de exceso de cemento en todas las superficies de los dientes. Resultados: No hubo diferencias estadísticamente significativas entre la adaptación de las coronas de acero y el estado gingival. El único indicador relevante fixe la superficie vestibular (p = 0,018). Por otra parte, el estado gingival y la biopelíeula presentaron una baja correlación (¡9 %). Conclusiones: El índice gingival de dientes restaurados con coronas de acero y sin estas presentó una correlación positiva entre la inflamación gingival y la edad de la población pediátrica, aun cuando la retención de biopelíeula no fue significativa.

Bideground: Ihc use of steel crowns enables to preserve the temporary teeth until their physiological changeover; however, in the literature there is a controversy regarding the behavior of the gingival tissue around teeth restored with steel crowns. Purpose: To analyze the gingival condition around the temporary teeth that have been restored with and without steel crowns in children from 3 to 9 years old who attended to the dental clinic at the Pontificia Universidad de Colombia in Bogotá between 2013 and 2014. Methods: A cross-sectional descriptive study was carried out and 110 temporary teeth restored with steel crown were observed and compared to the teeth restored without it. Biofilm and gingival indexes were analyzed as well as the steel crown clinical adaptation and the presence of cement excess in any of the dental surfaces. Results: No significant statistical difference was found bccwccn the steel crown adaptation and the gingival condition. 'Ihc only relevant indicator was the vestibular surface (p = 0.018). On the other hand, both the biofilm and the gingival condition showed a poor correlation (19%). Conclusions: Ihc gingival index in teeth restored with and without steel crown showed a positive correlation between gingival inflammation and the children populación age, even chough the biofilm retention was not significant.

Periapical Status of Root-filled Teeth Restored with Composite, Amalgam, or Full Crown Restorations: A Cross-sectional Study of a Swedish Adult Population.

INTRODUCTION: The aim was to compare the periapical status of root-filled teeth restored with resin composite, laboratory-fabricated crowns, or amalgam in a Swedish adult population. METHODS: The subjects consisted of 440 individuals from a randomly selected sample of 1000 adult residents of a Swedish county. The type, material, and quality of the restorations were recorded for all root-filled teeth by using clinical examination and intraoral clinical photographs. Periapical status, root-filling quality, and marginal bone loss were evaluated on panoramic radiographs. The association between periapical status and type, material, and quality of the restorations was analyzed by using the χ(2) test and logistic regression. RESULTS: No difference in the frequency of apical periodontitis (AP) between teeth restored with resin composite, laboratory-fabricated crowns, or amalgam (29.7%, 26.2%, and 43.1%, respectively) of adequate quality was found. No association between AP and resin composite restorations was disclosed; however, there was an association between AP and inadequate root-filling quality and marginal bone loss >1/3 of the root length. CONCLUSIONS: The results did not indicate any association between AP and resin composite restorations. Neither the type nor the material of the restoration was of significance for periapical status as long as the quality was adequate.

Convergence angles and margin widths of tooth preparations by New Zealand dental students.

STATEMENT OF PROBLEM: Fundamental crown preparation principles are taught and are highly regarded in dental education. Whether tooth preparations made by dental students match these principles is unclear. PURPOSE: The purpose of this retrospective study was to report the total occlusal convergence (TOC) and margin widths of crown preparations clinically prepared by New Zealand predoctoral dental students between 2013 and mid-2015. MATERIAL AND METHODS: A total of 371 stereolithography files of tooth preparations for metal ceramic crowns prepared by predoctoral dental students were extracted from the Technical Services Laboratory database at the University of Otago. The files were put through the preparation measuring software Preppr, with outputs being TOC angles in faciolingual and mesiodistal cross sections and margin widths in facial, lingual, distal, and mesial aspects. Means, standard deviations, 95% confidence intervals, and distributions using box and whisker graphs were calculated and presented. RESULTS: The majority of TOC angles fell within an acceptable range of 10 to 20 degrees; however, the angles ranged from undercuts (<0 degrees) to >60 degrees. The majority of margin widths were between 0.5 and 1 mm, while the maximum was approximately 2 mm and the minimum was 0 mm. CONCLUSIONS: Predoctoral dental students in New Zealand are able to produce literature-recommended TOC angles and margin widths for metal ceramic crowns; however, further attention and training are needed for excessive tooth preparations, mainly in the form of large TOC angles.

Utilizing CAD/CAM to Measure Total Occlusal Convergence of Preclinical Dental Students' Crown Preparations.

Traditionally, faculty assessment of preclinical crown preparations occurs by visualizing preparation features. However, contemporary CAD/CAM tools have the ability to more precisely evaluate preparation features, which is beneficial for psychomotor development. Taper is one of the most challenging features to objectively assess. The aim of this study was twofold: first, to validate the software's ability to distinguish differences in taper, and second, to compare traditional faculty assessment with digital assessment of taper. In the study, 30 all-metal crown preparations were created on typodont teeth with varying degrees of axial reduction and placed into three groups based on amount of taper (minimum, moderate, or excessive). Each tooth was scanned with the D4D scanner, and the taper was analyzed using E4D Compare. A second experiment used 50 crown preparations of tooth #19, which were done as a formative exercise. A comparison faculty assessment with CAD/CAM assessments of taper was performed. The results showed that when the taper was varied, E4D Compare was able to distinguish those differences; the Tukey post-hoc test revealed a significant difference (p=0.001). The qualitative analysis comparing faculty grading to CAD/CAM grading demonstrated a trend for CAD/CAM to be more precise. These results suggest that E4D Compare is an effective means of quantitatively measuring the amount of total occlusal convergence or taper on a crown preparation and that digital assessment may be more precise than faculty visual grading.

Effectiveness of Implant Therapy Analyzed in a Swedish Population: Prevalence of Peri-implantitis.

Peri-implantitis is an inflammatory disease affecting soft and hard tissues surrounding dental implants. As the global number of individuals that undergo restorative therapy through dental implants increases, peri-implantitis is considered as a major and growing problem in dentistry. A randomly selected sample of 588 patients who all had received implant-supported therapy 9 y earlier was clinically and radiographically examined. Prevalence of peri-implantitis was assessed and risk indicators were identified by multilevel regression analysis. Forty-five percent of all patients presented with peri-implantitis (bleeding on probing/suppuration and bone loss >0.5 mm). Moderate/severe peri-implantitis (bleeding on probing/suppuration and bone loss >2 mm) was diagnosed in 14.5%. Patients with periodontitis and with ≥4 implants, as well as implants of certain brands and prosthetic therapy delivered by general practitioners, exhibited higher odds ratios for moderate/severe peri-implantitis. Similarly, higher odds ratios were identified for implants installed in the mandible and with crown restoration margins positioned ≤1.5 mm from the crestal bone at baseline. It is suggested that peri-implantitis is a common condition and that several patient- and implant-related factors influence the risk for moderate/severe peri-implantitis (ClinicalTrials.gov NCT01825772).

Assessment of 68 Prosthodontic Crowns in 41 Pet and Working Dogs (2000-2012).

A search of the medical and dental records at the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania was conducted to identify dogs that received full or partial prosthodontic crowns over a 13-year period (2000-2012). Forty-one dogs with a total of 68 prosthodontic crowns were identified. Further criteria for acceptance into the study included presence of complete medical records containing adequate information pertaining to the procedures performed, and current follow-up either by telephone, electronic mail, or via in-person examination. Treatment was considered to be successful when the prosthodontic crown was in place and there was no further structural injury to the tooth upon making contact with the client or at the time of death of the dog confirmed by the client. The mean number of days the prosthodontic crowns remained in place without further injury to the tooth was 1,598 (range, 161-4, 464 days [median, 1,414 days], standard deviation 1,093 days). Bond failure between the cement and the tooth or the cement and the prosthodontic crown occurred in 3 cases (4.4%). Fracture of the prosthodontically treated tooth occurred in an additional 7 cases (10.3%). Treatment was classified as successful in 58 cases (85.3%). The results suggest that prosthodontic crown therapy is a successful, practical, and durable treatment option for protection of previously injured teeth in pet and working dogs.

An Up-to-15-Year Comparison of the Survival and Complication Burden of Three-Unit Tooth-Supported Fixed Dental Prostheses and Implant-Supported Single Crowns.

PURPOSE: To assess and compare the outcomes and economic complication burden of three-unit tooth-supported fixed dental prostheses (TFDPs) and implant-supported single crowns (ISCs) provided to a sequential cohort in a specialist prosthodontic practice over a 15-year period. MATERIALS AND METHODS: Sequential patients requiring replacement of a single missing tooth between 1996 and 2010 with a metal-ceramic three-unit TFDP (n = 145 patients, n = 174 prostheses) or ISC (n = 174 patients, n = 220 prostheses) were included. Prostheses subjectively judged at insertion to have an unfavorable 10-year prognosis (17 TFDPs, 0 ISCs) were removed from statistical analyses. The estimated cumulative survival (ECS) was calculated with the life table actuarial method and standard errors calculated with the Greenwood formula. Differences in outcomes between all prostheses and those replacing only anterior or only posterior teeth were assessed with the log rank test. Complication incidence, severity, and economic burden, measured in time/cost accounting units (TAUs), were tallied and compared descriptively. RESULTS: The 15-year ECS did not differ for 112 TFDPs (92.75% ± 3.28%) and 81 ISCs (95.95% ± 2.92%) replacing posterior teeth. However, the 15-year ECS was significantly greater for 139 ISCs (93.33% ± 6.44%) than for 45 TFDPs (82.82% ± 6.50%) replacing anterior teeth. The economic burden of nonterminal complications for both prostheses was low (mean = 0.3 and 0.2 TAUs per prosthesis for TFDPs and ISCs, respectively). This equated to 3 TAUs/100 years in clinical service and 4 TAUs/100 years in clinical service for the TFDPs and ISCs, respectively. CONCLUSION: The survival of three-unit TFDPs and ISCs over 15 years was not statistically different when replacing posterior teeth, but ISCs survived significantly better when replacing anterior teeth. The complication rates of the TFDPs and ISCs were similar, but the economic burden for the TFDPs was greater.