Preformed Crowns Research Articles

Adhesion of Candida albicans on preformed crowns used to restore primary molars: An in vitro study

BackgroundAssessing microbial biofilm adhesion to the restorative material’s surface is a key factor in determining its success. This study aimed to compare the adhesion of Candida albicans (C. albicans) on stainless steel crowns (SSCs) versus zirconia crowns (ZCs) used for primary molars. Study designThis in vitro study involved 20 full-coverage crowns, with 10 SSCs and 10 ZCs. A fungal adhesion assay was performed to evaluate C. albicans adhesion, using colony-forming units (CFU) and cell proliferation assays. StatisticsThe Wilcoxon–Mann–Whitney test was applied to compare the groups, with statistical significance set at 5 %. ResultsThe study revealed that SSCs had a lower mean CFU value (28.28 ± 4.557 CFU/ml) and cell proliferation rate (49.74 ± 0.4367) compared to the ZC group (30.70 ± 11.0760 CFU/ml and 74.53 ± 0.7014, respectively). However, these differences were not statistically significant. ConclusionThe findings suggest that the selection of crowns for restoring primary molars may not be influenced by C. albicans adhesion.

Perceptions, attitudes, and clinical experiences of Brazilian dental practitioners towards molar incisor hypomineralisation: a cross-sectional study.

To evaluate perceptions, attitudes, and clinical experience of Brazilian dental practitioners regarding molar incisor hypomineralisation (MIH). An online survey with 27 questions, covering professional profile data, perceptions, and knowledge on clinical management of MIH, was employed. Descriptive analyses, chi-square, Fisher's exact, and Cramer's V tests were used. Sample comprised 100 participants, equally distributed between those working in private or public sectors. Most private sector practitioners had 21-30years of clinical experience (28%) and master's degree (50%), while most public sector practitioners had 11-20years of clinical experience (32%) and a PhD degree (32%). Most participants (86%) recognized MIH in their practice. Statistically significant differences were observed in frequency (p = 0.001), incidence (p = 0.039), and lesion type (p = 0.043) between practitioners from both sectors. Uncertainly in management was reported by 49%, mainly in public sector. For mild MIH in incisors, no treatment was chosen (43%), and the treatment longevity was the only significant factor reported (p = 0.012). In cases of mild MIH in first permanent molars (FPMs), 51% of respondents opted to keep the affected tissue and apply fissure sealant. Glass ionomer (GI) restoration was commonly indicated for FPMs with severe MIH with moderate loss of structure and sensitivity (38%). In cases with substantial structural loss and pulpal involvement, the most chosen treatment was endodontic intervention combined with preformed crowns. Brazilian dental practitioners face MIH in clinical practice. Although, public sector professionals are less confident in diagnosis and treatment, no significant differences in treatment preferences between public and private sector dental practitioners were identified.

Assessment of masticatory performance in pediatric patients receiving preformed crowns by Hall technique: a controlled clinical trial.

The purpose of the study was to assess and compare the masticatory performance in children receiving preformed metal crown by Hall technique and conventional technique. Children having teeth indicated for restorative/endodontic therapy and belonging to the age group of six to ten years were invited to participate in the study. Eighteen children received preformed metal crowns (PMCs) by Hall technique. Meanwhile, nineteen children received preformed metal crowns by the conventional technique. Their masticatory performance (MP) was assessed at T0 (pre-intervention), T1 (day 1 post-intervention), T2 (1week), T3 (2weeks), T4 (1month) and T5 (3months) using Hue-check Gum® (University of Bern, Switzerland). The chewing gum samples were scanned within 24h of their collection and processed in the ViewGum Software©. The software calculated the hue value (VOH) which indicated the masticatory performance of the individual. A questionnaire was given to the parents at T4 and T5 to assess any discomfort or pain associated with PMCs placed in both groups. The evaluation of masticatory performance using the two-color chewing method revealed reduction in MP on day 1 post-intervention (p < 0.001) for both groups. However, the MP values recorded at T5 were comparable to the baseline values at T0 (p = 0.009). No significant discomfort or pain was reported in both groups. The findings of the current clinical study indicate that placement of PMCs by both conventional and Hall technique in children deteriorates their MP which equilibrates within 1month. CTRI/2021/02/031532 [Registered on: 25/02/2021]-Trial Registered Prospectively.

Performance of restorations in primary molars over a seven-year period

ObjectiveThe aim of this study was to evaluate the use and reintervention rate of fillings compared to preformed metal crowns in the everyday clinical practice of German dentists. MethodsIn this retrospective, longitudinal analysis, fee codes from the Kassenzahnärztliche Vereinigung Westfalen-Lippe for restorations placed in primary molars between 2012 and 2015 in children until 7 years of age followed for a 7-year period (latest until December 2022) were filtered and analyzed with the Fine and Gray competing risk regression and Cox proportional hazards regression to calculate the risk of reintervention divided into the main outcomes “Successful”, “Minor Failure/Repair” and “Major Failure/Endodontic Treatment/Extraction”. 367,139 primary molars (one-surface fillings: n = 117,721; two-surface fillings n = 198,815; three-surface fillings n = 36,695; more than three-surface fillings n = 8,267 and preformed metal crowns n = 5,641 were included in this study. ResultsTeeth treated with preformed crowns needed significantly less re-interventions. Subdistribution hazard ratio for minor events was 0.117 (95 %-CI: 0.097 to 0.141) and hazard ratio of major events (HR=0.786; 95 %-CI: 0.695 to 0.890) when compared to one-surface fillings in multivariable adjusted analysis. Within 7-year follow-up preformed crowns required less repairs (80.6 % success rate, minor failure 4.4 %, major failure 16.3 %) than the teeth treated with composite fillings (46.2 %–52.6 % success rate, minor failure 27.0 %–39.5 %, major failure 15.5 %–28.4 %, p < 0.001). ConclusionWithin the German healthcare system fillings are the first choice for treating primary molars despite considerably higher reintervention rates. This encourages a discussion on the indication of fillings and the more durable preformed metal crowns to reduce unnecessary reintervention in young children. Clinical significanceThis study gives an unprecedented insight into the German healthcare system regarding the reintervention rates of the most relevant treatment techniques for caries in primary molars.

Paedodontic preformed crowns in primary teeth and relative degree of dental wear.

Prosthetic rehabilitation of deciduous teeth in paediatric age using pre-formed crowns has been considered one of the best methods of dental restoration since their introduction. Their main advantages are related to durability, longevity and a low rate of recurrent cavities. Since stainless steel crowns do not coincide with aesthetic needs of parents and patients, preformed paedodontic crowns made of zirconia and nano-hybrid composite was introduced. The aim of the study is to evaluate the degree of wear on the enamel and on themselves of the different paedodontic crowns. Nine bovine teeth and nine paedodontic crowns for deciduous molars were selected for the study, three of which in zirconia, three in nano-hybrid composite and three in stainless steel. Wear test was carried out on the Rtech™ Instruments tribometer applying a force of 50 N. After that, both the bovine teeth and the paedodontic crowns were observed using a stereo microscope (Zeiss Stemi C-500) and a scanning electron microscope (SEM, Cambridge Stereoscan 440). The areas of wear were calculated with a software [ImageJ, version 1x, Wayne Rasband, Maryland, USA]. Pre-formed paediatric crowns in zirconia, nano-hybrid composite and stainless steel are a valid aid for the restoration of deciduous teeth and do not compromise the physiological wear characteristic of the phases of the dental exchange. The stainless steel crown is preferable for the restorations in the posterior sectors as its behaviour is the most similar to that of a natural tooth. Zirconia and nano-hybrid composite crowns showed an inversely proportional behaviour between their wear volume and that of the opposing tooth.

Biocompatibility and acid resistance of preformed crowns in children: an in vitro study

PurposeTo investigate the in vitro biocompatibility of human gingival fibroblasts with preformed paediatric crowns and resistance to acid exposure at levels that simulate the oral environment.MethodsThis laboratory study investigated primary HGFs viability, metabolic activity, cytotoxicity, and apoptotic events on preformed metal crown discs, composite resin-coated wells, and monolithic zirconia fragments at 24, 48, and 72 h using the ApoTox-Glo Triplex assay. The PPCs were also immersed in 0.1% lactic acid, 0.2% phosphoric acid, or 10% citric acid for 7 days at 37 °C to reproduce conditions associated with dietary intake or gastric reflux. Samples were then subject to inductively coupled plasma optical emission spectrometry to quantitate the release of ions.ResultsThe viability of HGFs on stainless steel and CR significantly declined at 48 and 72 h, representing potential cytotoxicity (p < 0.05). Cytotoxicity of HGFs was also higher for stainless steel and ZR compared to control (p < 0.05). PMCs and ZR crowns gave minimal ion release. Meanwhile, significant quantities of metallic ions, including copper (Cu), iron (Fe), nickel (Ni), and zinc (Zn), were present in eluates from veneered-preformed metal crowns.ConclusionAs PPCs can be exposed to highly acidic environments for many years, thus the release of metallic ions from V-PMCs should form the further investigation in future studies.

Fracture strength of preformed zirconia crown and CAD-CAM zirconia, ceramic, and hybrid composite crowns for the restoration of primary molars: An invitro study.

Paediatric-preformed zirconia crowns have been associated with several issues, primarily their inability to be crimped and the need for extensive tooth preparation. Additionally, the capacity to adjust the size, shape, and fit of these crowns is very limited. To evaluate and compare the fracture strength of four different types of dental crowns intended for paediatric patients. The fracture resistance of four types of paediatric crowns was evaluated using the universal testing machine; freshly extracted primary molars received one of the following: preformed zirconia crowns, custom-made computer-aided design and computer-aided manufacturing (CAD-CAM) zirconia crowns, custom-made CAD-CAM ceramic crowns, and custom-made CAD-CAM hybrid composite crowns. Data were statistically compared using the Kruskal-Wallis test followed by the Bonferroni test, and the level of significance was set at 5%. Results showed that there was a statistically significant difference among the four groups (p < .001). The highest value of fracture force was observed for the milled zirconia crown and the lowest for the prefabricated zirconia. The implementation of the CAD-CAM digital crown fabrication technique has the potential to address issues associated with preformed crowns in paediatric patients, particularly in terms of fracture resistance.

Clinical Evaluation of Maneuverability and Durability of Titanium Nitride-coated Preformed Crown on Primary Molar Teeth: A Randomized Controlled Trial.

The management of multisurface carious primary molar is challenging. Currently, the ideal choice for the management of extensive multi-surface carious primary molar is the placement of a preformed stainlesssteel crown (SSC)/preformed zirconia crown. Unfortunately, conventional preformed SSCs are frequently refused by parents for esthetic reasons, while the preformed zirconia crown has its own disadvantages like high cost and excessive tooth preparation. To evaluate the maneuverability and durability of titanium nitride-coated crowns on primary molar teeth and to assess the child-parent satisfaction of titanium nitride-coated gold-colored preformed crowns over metal-colored preformed SSC on primary molar teeth. Randomized controlled trial conducted on children between the age-groups of 6- and 9-year-old children. Group I for titanium nitride-coated preformed crown and group II for preformed SSC (control group) were allotted with a simple random technique. The maneuverability of the titanium nitride-coated crowns was evaluated in comparison with preformed SSC in terms of the level of difficulty while trimming, contouring, crimping, and wearing out of titanium nitride coating while manipulating. Participants of group I were recalled for follow-up in the 1st, 6th, and 12th months to evaluate the durability of the titanium nitride coating on the preformed crowns. There were no failures at the 12-month follow-up in terms of the durability of the titanium nitride coating, and there was no significant difference seen in terms of the maneuverability of both crowns. Overall, child-parent satisfaction was good with gold-colored titanium nitride-coated crowns. The study concluded that titanium nitride-coated gold crowns could be a boon to pediatric dentistry and serve as an alternative to metal-colored SSCs. Vundela RR, Gupta N, Balamurugan S, et al. Clinical Evaluation of Maneuverability and Durability of Titanium Nitride-coated Preformed Crown on Primary Molar Teeth: A Randomized Controlled Trial. Int J Clin Pediatr Dent 2023;16(S-3):S263-S267.

A two-year retrospective study on traumatic dental injury in the primary dentition.

The aim of this study was to analyze the causes, clinical characteristics, social factors, and current status of treatment of traumatic dental injury (TDI) in the primary dentition. A retrospective analysis was performed on 144 children (213 teeth) with TDI in the primary dentition from our hospital between December 2017 and June 2020. Data were analyzed using the chi-square test and the Mann-Withney-Wilcoxon test. Boys accounted for 68.1% (98/144) and girls for 31.9% (46/144) of all 144 children with TDI in the primary dentition, with a boy-girl ratio of 2.13:1. The primary age of TDI in deciduous teeth was 2 to 4 years old, accounting for 59% of all cases. Collision with others and fall were the 2 main causes of trauma to the deciduous teeth, making up 52.1% and 44.4% of all causes, respectively. Crown fracture injury was the most common type of TDI in the primary dentition, accounting for 37% of all cases (53/144). Of the 144 cases, 17.4% (25/144) was accompanied by soft tissue laceration, while 22.2% (32/144) by swelling or contusion of tissue. Maxillary teeth (92.4%) were more vulnerable to injury than mandibular teeth (7.5%), with maxillary incisor being the most vulnerable 1 (91.5%). The percentage of children arrived at the hospital for treatment 24 hours after the injury was the highest (57.0%, 82/144). After the hospital visit, 74.3% of children received treatment for the dental trauma. In terms of the treatment modalities, extraction of the traumatized teeth (27.1%) and pulpectomy + resin filling (or preformed crown) restoration were predominant. Approximately 28.5% (41/144) of cases were reviewed within 2 years, with the proportion of children with pulpitis or periapical infection being the highest (29.3%, 12/41). Age, gender, collision, and fall are the factors linked to a higher risk of TDI in the primary dentition in children under the age of 7. Resin filling (or preformed crown) restoration and pulpectomy are effective in preserving the affected tooth and controlling infection. However, the preservation of the affected tooth and the prevention of infection may be hampered by late visits and low follow-up rates.

Clinical and radiographic performance of preformed zirconia crowns and stainless-steel crowns in permanent first molars: 18-month results of a prospective, randomized trial

BackgroundThe treatment of young permanent first molars with extensive carious tissue loss may often require restoration with preformed crowns. This study compared the clinical and radiographic performance of stainless-steel crowns (SSCs) and preformed zirconia crowns (ZCs).MethodsForty-eight molar incisor hypomineralisation (MIH)- or caries-affected permanent molars in 20 healthy patients between 6–13-year-old were randomly divided into ZC and SSC groups (n = 24 teeth/group) in a split-mouth design. The oral hygiene levels of patients were assessed using Greene and Vermillion simplified oral hygiene index (OHI-S). Plaque accumulation and gingival health were evaluated using the Silness&Löe plaque index (PI) and Löe&Silness gingival index (GI), respectively. Clinical retention, marginal extension level, marginal adaptation of crowns and wear of the antagonist teeth were assessed at baseline, 1, 6, 12 and 18 months. The radiological assessments for evaluating the marginal adaptation of crowns and periapical pathology of crowned teeth were performed at 6 and 12 months. The data were analyzed using Kaplan–Meier analysis, Mann–Whitney U test, and two-way ANOVA.ResultsA total of forty teeth in 17 children were evaluated for 18 months. ZCs had significantly lower gingival and plaque index values than teeth restored with SSCs during all evaluation periods (p < 0.05). Neither crown type resulted in clinically-detectable wear on opposing dentition or periapical pathology. One ZC was lost at 13 months, while all SSCs survived in function clinically. The cumulative survival rates of ZCs and SSCs were 95.2% and 100% respectively.ConclusionsBoth ZCs and SSCs showed high clinical retention rates in young permanent molars. ZCs had lower plaque accumulation and better gingival health than SSCs, which were consistently associated with mild gingival inflammation.Clinical Trial Registration NumberNCT05049694.

Comparative Evaluation of the Survival Rates of Zirconia Crown and Stainless Steel Crown for Proximal Caries in Primary Molars: a Retrospective Study

Due to increasing demand for aesthetics, zirconia crowns have become a popular choice for treating primary molars. However, there is limited literature available comparing the survival rates of zirconia crowns with those of other restorative materials. The objective of this study was to compare the 36-month survival rates of zirconia crowns and stainless steel crowns for proximal caries, as well as to analyze failure types associated with each crown type. Electronic medical records and radiographs of 1,061 primary molars from 498 patients treated with 2 types of prefabricated crowns at Chosun University Dental Hospital and 2 private dental clinics between 2017 and 2019 were collected and analyzed. The survival rate of zirconia crowns was found to be lower compared to that of stainless steel crowns. Regarding the groups without pulp treatment, the survival rate of stainless steel crowns was significantly higher than that of zirconia crowns. However, in the groups that received pulp therapy, no significant difference in the survival rates was observed between the two preformed crowns. Notably, abnormal root resorption or periapical lesions were identified as the primary cause of restorative failure in stainless steel crowns, whereas loss of restoration was the predominant cause in zirconia crowns. This study holds valuable implications for clinicians when selecting preformed crowns for primary molars.

COMPARATIVE EVALUATION OF COLOUR CHANGE, CRAZING AND DIMENSIONAL STABILITY OF STAINLESS STEEL, ZIRCONIA AND FIGARO CROWNS BY STERILIZATION

Introduction:Full coverage restorations are indicated in primary teeth following pulp therapy, in teeth with multi-surface caries, developmental defects and fractures. There are various types of restorations for complete coverage. In the process of trial and error, the crown gets contaminated and demands sterilization for the purpose of reuse. Therefore, the study was carried out to evaluate the physico-mechanical outcome after sterilization of paediatric preformed crowns. Aim: The purpose of the study was to compare the effect of sterilization on the colour, crazing and dimensional stability of Stainless steel, Zirconia and Figaro crowns. Methodology: The study was conducted on a total of 36 crowns consisting of 12 each, Stainless steel crowns, Zirconia crowns and Figaro crowns, which were divided into two groups: G1 in which crowns did not undergo any sterilization, G2 consisted of sterilization with steam autoclaving at 121°C, 15 psi pressure for 20 min. Following sterilization, all the crown samples were observed under a stereomicroscope at ×200 magnification and assessed for colour change, crazing and dimensional stability. Results:There was no color change or crazing following sterilization among crowns in any of the groups. Highest crazing was noted in stainless steel and the least in Zirconia crowns. Zirconia Crowns were the most dimensionally stable followed by Figaro crowns and SSCs were the least dimensionally stable. Conclusion: Zirconia Crown was the most dimensionally stable followed by Figaro Crowns and Stainless steel crowns.

Various Types of Preformed Crowns Used in Pediatric Dentistry: A New Appraisal

The aim of this analysis is to compare and contrast the numerous categories of preformed crowns that can be used to restore the primary teeth in children. Historically, preformed crowns have been widely available for the past 50 years. The clinical performance of preformed crowns has evolved to meet higher functional, mechanical, and aesthetic demands. Preformed crowns are available in a range of prefabricated sizes and shapes. Preformed crowns can vary depending on their properties, compounds, methods of preparation and biocompatibility.

Success rate of the treatment of early childhood caries under general anesthesia: A retrospective cohort study in different periods.

The purpose of this study was to evaluate the three-year success rate of the treatment for early childhood caries (ECC) under general anesthesia in different periods (2011 and 2018). Children (<6 years old) who had severe caries and were treated under general anesthesia in 2011 and 2018 were selected and followed up by telephone appointment and clinical examination. Success rate of each treatment was determined and possible factors associated with treatment failure were evaluated. There were 153 patients (with an average age of 48.55 ± 13.37 months) and a total of 2,018 teeth included in the 2011 group. In the 2018 group, there were 273 patients with an average age of 49.01 ± 12.42 months and a total of 3,796 teeth. The success rate in the 2011 group was significantly lower than that in the 2018 group. Teeth with mineral trioxide aggregate (MTA)-capped pulp survived significantly longer than those with calcium hydroxide-capped pulp. The utilization rate of preformed crown restoration was higher than that of resin restoration, and the survival time of dental restorations with preformed crown was prolonged. For posterior teeth, the success rate of indirect pulp capping and pulpotomy was also significantly higher than those without preformed crowns. General anesthesia is a safe and effective behavioral management method for uncooperative children's dental treatment. The use of biocompatible pulp capping materials and preformed crowns improved the success rate of treatment and prolonged the survival time of affected teeth.

Clinical evaluation and parental and child satisfaction with restoration of primary teeth using zirconia and stainless steel crowns: A randomised clinical study

Introduction: Full-coronal restoration is the choice of treatment for restoring pulpally treated tooth or tooth with multiple surface involvement. In paediatric dentistry, semi-permanent stainless steel crowns (SSCs) are considered gold standard, but with increasing need of aesthetics, zirconia crowns have started gaining importance. Hence, this study was conducted to evaluate the clinical performance of SSCs and zirconia crowns and to compare the child satisfaction and parental ratings of impact of treatment using these preformed crowns. Materials and Methodology: This study was a part of randomised controlled trial performed on 60 children of 4–8 years old. The primary molars were cemented with either SSCs or zirconia crowns and were evaluated clinically at baseline, 6-month and 12-month follow-up for crown retention, crown fracture, gingival and debris index, wear, marginal integrity and recurrent caries. The trials also evaluated parental satisfaction and child satisfaction based on five-point Likert scale at the end of 12-month follow-up. The data were analysed using Chi-square test for categorical data and independent sample t-test for quantitative data. Results: Both the crowns were 100% retentive at 12-month follow-up. Fair debris score and mild gingivitis were reported in 3% with SSC at 6–12 months. One zirconia crown fractured at 12 months. Fifty-four per cent of parents in zirconia and 57% in SSC stated that the crowns improved masticatory function. Children reported a mean Likert score of 3.0 for SSC and 4.89 for zirconia which was highly significant. Conclusion: Both the crowns increased the overall health of crowned tooth and were fully retentive for the studied duration. However, zirconia crowns were more gingival friendly and had an edge over SSC in terms of aesthetics.

Knowledge, perception, and clinical experiences on molar incisor hypomineralization amongst Portuguese dentists

AimMolar incisor hypomineralization (MIH) is a prevalent oral health condition whose knowledge by dentists is key to the best clinical outcome. This study aimed to evaluate the knowledge, perceptions and clinical experiences of MIH among Portuguese dentists.MethodsA cross-sectional structured questionnaire was distributed nationally through a web-based survey platform. Data concerning demographic variables, years of experience, dental specialty, MIH prevalence, diagnosis, severity, training demands and clinical management of MIH were collected. We calculated a knowledge score (KS), and compared data between Pediatric Dentists (PDs), General Dental Practitioners (GDPs) and other dental specialties (ODS).ResultsOverall, 2.2% of Portuguese dentists (n = 257) answered the questionnaire. Most participants reported having identified MIH in their practice (82.5%), with PD reporting the prevalence appeared to have increased, and practically all (91.7%) considered it a public health problem. Resin composite was often the used material to restore MIH teeth (56.0%), however PDs indicated glass ionomer cements as the preferred and preformed crowns a better option. The average KS on MIH was 41.3 (± 5.7), with GDPs having a similar score than PDs. Most respondents (94.9%) reported a lack of information about MIH and were willing to receive appropriate clinical training.ConclusionsThe average knowledge on MIH was considered low among Portuguese dentists. Respondents perceived an increased incidence of MIH, despite the lack of prevalence data in Portugal. The material of choice was Glass Ionomer and performed crowns, by PDs, while GDPs and ODS reported poor confidence to manage MIH. These results may serve future programs to increase knowledge, perceptions and clinical experiences towards MIH.

Clinical Evaluation of Pediatric Posterior Zirconia and Stainless Steel Crowns: A Comparative Study.

ObjectiveTo clinically evaluate and compare the performance of posterior pediatric zirconia crowns with stainless steel crowns.Materials and methodsTwenty nine children [3-9 years] were selected and given 70 preformed crowns [35: preformed zirconia crowns, Kinderkrown; 35: stainless steel crowns, KIDZ CROWN]. Crowns were evaluated for retention, marginal integrity, opposing tooth wear, plaque accumulation, gingival inflammation, and proximal contact at 3, 6, 9, and 12th month.ResultsAt the end of follow-up period overall success rate with zirconia crown was 93.5% and that of stainless steel crown was 96.7%. Statistical analysis showed no difference between the groups.ConclusionPosterior preformed zirconia and stainless steel crowns showed good clinical performance. Preformed zirconia crowns can be an option for posterior full coronal restoration when esthetics is of prime concern for the parent and child.How to cite this articleMurali G, Mungara J, Vijayakumar P, et al. Clinical Evaluation of Pediatric Posterior Zirconia and Stainless Steel Crowns: A Comparative Study. Int J Clin Pediatr Dent 2022;15(1):9-14.

Review on Preformed Crowns in Pediatric Dentistry—The Composition and Application

The purpose of this review is to compare and contrast the various types of preformed crowns that can be used to restore the primary teeth in children. Historically, preformed crowns have been widely available for the past 50 years. The clinical performance of preformed crowns has evolved to meet higher functional, mechanical, and aesthetic demands. Preformed crowns are available in a range of prefabricated sizes and shapes. Preformed crowns can vary depending on their properties, compounds, methods of preparation, and biocompatibility.

Fracture strength of preformed zirconia crown and new custom-made zirconia crown for the restoration of deciduous molars: in vitro study.

Preformed metal crown (PMC) were considered as the best method of restoring primary molars. In recent years, dentistry has seen the emergence of esthetic full-coverage restorative alternatives that gave better results but their ability to manipulate the size, shape, and fit is very limited. The milled zirconia crown is a new alternative for the restoration of deciduous teeth, but the mechanical properties of these restorations need to be tested. To assess and compare the force required to fracture on two posterior pedodontics crowns: a prefabricated Zirconia crowns (PZC) (NuSmile Zr Zirconia®) and a new custom-made zirconia crown (also called Zirkid©) on a freshly extracted deciduous molars. Thirty freshly extracted deciduous molars were selected and were randomized into two groups: (1) molars prepared to receive the PZC and (2) molars prepared to receive the milled zirconia crowns. All pediatric crowns were cemented with glass ionomer and the samples were placed in the thermocycling machine for thermal aging of 1000 cycles. Mechanical compression forces were applied using the Universal Testing Machine until fracture of the crowns. The force required to fracture were evaluated. Since variable was normally distributed with Kolmogorov-Smirnov test, Student t test was used for statistical comparison. This study showed that the mean fracture force was significantly elevated with zirconia crowns made with Zirkid© (2888.6 ± 1060.2N) compared to NuSmile Zr crowns (646.5 ± 223.9N) (p value < 0.001). Considering the limitations of the present in vitro study, further in vitro and in vivo studies are required to support the use of Zirkid© in primary molar teeth restorations and to assess others mechanical properties.

Effects of decontamination protocols on the aesthetic, morphological, and material composition of preformed paediatric crowns

Preformed crowns (PCs) are exposed to potentially infectious bodily fluids during the trial fit; however, whether they can be safely re-used remains uncertain. This study determined the effects of decontamination methods on various PCs. The key criteria examined were aesthetic, morphological, and elemental characteristics. This is a laboratory-based experimental study. Stainless steel, pre-veneered stainless steel, and zirconia PCs underwent either: (a) ultrasonic cleaning with EmPower® followed by steam sterilisation, (b) thermal disinfection in an instrument washer with Asepti® Neutraliser/Asepti® followed by steam sterilisation, or (c) immersion in an ortho-phthalaldehyde (OPA) instrument-level disinfectant. The methods were performed for 1, 5, or 10 cycles, and scanning electron microscopy (SEM); red, green, and blue (RGB) value; and luminosity value were tracked (using a histogram of individual colour reference chips in Adobe Photoshop® ) to assess colour changes, and energy-dispersive X-ray (EDX) spectroscopy to characterise the material composition. Pre-veneered stainless steel crowns showed isolated zones of darkening with loss of luminosity and variations in green and blue values after ultrasonic or thermal washer disinfection combined with steam autoclaving at 5 and 10 cycles. No changes occurred with OPA. Both SEM imaging and EDX analysis identified no changes to crown materials from any of the three reprocessing methods. Reprocessing protocols need to reflect the differing responses of various types of PCs. Repeated steam sterilisation causes slight aesthetic alterations by way of colour instability and loss of luminosity to pre-veneered stainless steel crowns, but no issues with stainless steel or zirconia PCs.