Evaluation of Prosthodontic Complications in Screw-Retained and Cement-Retained Crowns in Dental Implants: An Original Research.

Aim: Single-tooth implant restorations, whether screw-retained or cement-retained, are essential for prosthodontic rehabilitation despite having low design flexibility, cosmetic appeal, and high 5-year survival rates. Materials and Methods: A study involving 14 patients with missing mandibular first molars used 28 implants and cement-retained and screw-retained prostheses. Patients had a single edentulous gap, adequate dental hygiene, and sufficient bone volume at the implant site. The study adhered to the Helsinki Declaration, followed WHO 2007 safety guidelines, and evaluated soft tissue, bone height, and bone loss. Data analysis included the Student's t-test and Mann-Whitney U-test. Results: In patients between the ages of 17 and 46, single-implant restorations were compared with cement- and screw-retained at 6 months. Abutment screw loosening and peri-implant soft-tissue traits did not differ significantly from one another. Conclusion: The study compared screw- and cement-retained implant restorations in 28 single-tooth implant-supported prostheses over a 6-month functional loading period, finding no significant improvement in either approach.

Aesthetic Outcome and Patient Perception of Immediate vs. Delayed Loading of Implant-Supported Single Crowns: A Randomized Controlled Trial.

Background: This randomized controlled trial aimed to compare the aesthetic outcome and patient perception of immediate versus DL of implant-supported single crowns. Methods: A total of 60 patients with a single missing tooth were enrolled and randomly assigned to two groups: immediate loading (IL) and delayed loading (DL). Each group consisted of 30 patients with a total of 30 implants. In the IL group, crowns were loaded onto implants immediately after placement, while in the DL group, a healing period of 3 months was observed before crown placement. Aesthetic outcome was assessed using the Pink Esthetic Score (PES) for soft tissue and the White Esthetic Score (WES) for the crown. Patient perception was evaluated through a visual analog scale (VAS) for satisfaction, comfort, and overall experience. Results: The IL group demonstrated comparable aesthetic outcomes to the DL group, with mean PES and WES scores of 10.2 ± 1.5 and 8.7 ± 1.2, respectively, in the IL group, and 10.5 ± 1.3 and 8.5 ± 1.4 in the DL group. Patient perception in terms of satisfaction, comfort, and overall experience was similarly high in both groups, with VAS scores above 8 for each parameter. Conclusion: This randomized controlled trial suggests that both IL and DL of implant-supported single crowns result in favorable aesthetic outcomes and high levels of patient satisfaction.

Evaluation of the clinical application of personalized 3D printing and CAD/CAM resin crowns to replace stainless steel crowns in paediatric dentistry.

BACKGROUND: Children with dental caries are treated with stainless steel metal crowns (SSC), but the aesthetics and precision still need to be improved. Currently, both 3D-printed resin crowns (PRC) and computer-aided design/computer-aided manufacture (CAD/CAM) resin crowns (CRC) meet the clinical requirements for crown applications in terms of strength, production time, cost, and aesthetics. AIM: This study replaced SSC with customized resin crowns by 3D printing and CAD/CAM. DESIGN: In this study, PRC, CRC, and SSC were used for incisor and molar restorations, and 60 crowns were made with 10 for each group. The fabrication efficiency, surface characteristics, marginal fit, and stability of the two different crowns were evaluated. RESULTS: PRC and CRC show superior color and surface characteristics, though production times are longer (5.3-12.4 times and 3.3-9.1 times, respectively) than for SSC (p < .05). They, however, can be completed within 80 min. Edge gaps for PRC and CRC are significantly lower (13.0-19.2 times and 13.0-13.7 times) than for SSC (p < .05). All materials exhibit good stability. CONCLUSION: The 3D-PRCs and CAD/CAM resin crowns may replace SSCs as a potential choice for clinical child caries.

Trueness, physical properties, and surface characteristics of additive-manufactured zirconia crown.

OBJECTIVE: This study aimed to conduct a comparison of trueness and physical and surface properties among five distinct types of additive manufactured (AM) zirconia crowns and zirconia crowns produced using the subtractive manufacturing (SM). MATERIAL AND METHODS: Zirconia crowns were fabricated using five distinct techniques, each varying in the method of slurry transfer and photocuring source. Each experimental group utilized either one of the four digital light processing (DLP)-based techniques (DLP spreading, DLP spreading gradation, DLP vat and DLP circular spreading) or the stereolithography (SLA)-based technique (SLA spreading). The control (CON) group employed SM. To assess accuracy, trueness was measured between the scan and reference data. To analyze the physical properties, voids were examined using high-energy spiral micro-computed tomography scans, and the crystal structure analysis was performed using X-ray diffraction (XRD). Surface roughness was assessed through laser scanning microscopy. RESULTS: Differences in the trueness of internal surfaces of crowns were found among the groups (P < 0.05). Trueness varied across the measurement surfaces (occlusal, lateral, and marginal) in all the groups except for the DLP spreading gradation group (P < 0.05). Voids were observed in all AM groups. All groups showed similar XRD patterns. All AM groups showed significantly greater surface roughness compared to the CON group (P < 0.001). CONCLUSION: The AM zirconia crowns showed bubbles and a rougher surface compared to the SM crowns. All groups exhibited typical zirconia traits and trueness levels within clinically acceptable limits, suggesting that current zirconia AM techniques could be suitable for dental applications.

Tensile bond strength between paediatric prefabricated zirconia crowns and primary maxillary incisors when using various types of luting cements: an in vitro study.

PURPOSE: There is limited evidence regarding the most appropriate type of luting cement for paediatric prefabricated zirconia crowns (PZCs) in primary maxillary incisors. The retention of PZCs is dependent on the bond strength of luting cement between PZCs and primary maxillary incisors. The aim of this study was to evaluate the tensile bond strengths between PZCs and primary maxillary incisors with different types of luting cements. METHODS: Thirty freshly extracted human primary maxillary incisors were prepared and randomly divided into three groups corresponding to three luting cements: bioactive cement, resin cement, and resin-modified glass ionomer cement (RMGIC), and then restored with PZCs. Tensile bond strengths were evaluated by a universal testing machine. The results were analysed using one-way ANOVA with Tukey's post-hoc test (p < 0.05). RESULTS: The means of the tensile bond strengths were 1.43 ± 0.85 MPa, 0.91 ± 0.63 MPa, and 0.56 ± 0.39 MPa for the bioactive cement, resin cement, and RMGIC groups, respectively. A significant difference in tensile bond strength was observed between the bioactive cement and the RMGIC group (p < 0.05) but there was no significant difference in tensile bond strength between the resin cement group and the others. CONCLUSION: Types of luting cement influenced the tensile bond strength between PZCs and primary maxillary incisors. The bioactive cement showed higher tensile bond strength than the resin cement and RMGIC.

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

PURPOSE: To 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. METHODS: This 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. RESULTS: The 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. CONCLUSION: As 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.

Influence of thermal aging on the marginal integrity of computer aided design/computer aided manufacturing fabricated crowns.

Background/purpose: The adaptation and marginal integrity of computer-aided designed and computer-aided manufactured (CAD/CAM) crowns after exposure to thermal aging need to be investigated. The present in-vitro study was designed to investigate the marginal integrity of CAD/CAM fabricated crowns cemented on extracted teeth after thermocycling aging. Materials and methods: Twenty-six newly extracted human premolars were prepared for full-coverage CAD/CAM crowns and were divided into two groups (leucite-reinforced glass-ceramics and lithium disilicate glass-ceramics). Both crowns' groups were cemented using dual curing resin cement. All specimen margins were measured for marginal integrity using an imaging system 24 h post cementation; then after 1, 3, and 5 estimated clinical years (10,000, 30,000, and 50,000 thermocycles). Two-way ANOVA analysis were used to determine whether the mean value difference is significantly different (ɑ = 0.05). Results: The average margin gaps recorded for leucite-reinforced glass-ceramic crowns were: 82.61 µm initial, and 91.02 µm after 5 estimated clinical year). For the lithium disilicate glass-ceramic crowns, the average margin gaps recorded were: 100.01 µm initial, and 120.21 µm after 5 estimated clinical year. During all measuring intervals, the leucite-reinforced glass-ceramic crown group had a lower marginal discrepancy. No statistically significant difference between the two groups was recorded. Conclusion: After being subjected to thermocycling, both CAD/CAM ceramic crowns, exhibited an increase in their marginal discrepancy; the difference was within the accepted clinical range.

Influence of attaching mechanical retentive devices onto frameworks on fracture resistance of implant-supported zirconia crowns.

This study investigated the fracture load of implant-supported zirconia crowns (IZCs), in which indirect composite resin or feldspathic porcelain was layered onto zirconia frameworks with mechanical retentive devices. Three different zirconia frameworks were assessed: attaching mechanical retentive devices on glaze and opaque porcelain materials (GL and OP groups, respectively), and no attaching mechanical retentive devices (ND group). The frameworks were layered using feldspathic porcelain (FP veneer) and indirect composite resin (IC veneer). Fracture load of the specimens was measured. In FP veneer, the GL group recorded the highest fracture load. In the IC veneer, the GL and OP groups had significantly higher fracture load than the ND group. The fracture resistance of IZCs can be enhanced by applying glaze material before attaching mechanical retentive devices for porcelain layering. The mechanical retentive devices effectively yielded mechanical interlocking between the zirconia frameworks and the IC veneer in GL and OP groups.

Effect of crown retention systems and loading direction on the stress magnitude of posterior implant-supported restorations: A 3D-FEA.

This study aimed to investigate the effect of four retention systems for implant-supported posterior crowns under compressive loading using three-dimensional finite element analysis. A morse-taper dental implant (4.1 × 10 mm) was designed with Computer Aided Design software based on non-uniform rational B-spline surfaces. According to International Organization for Standardization 14,801:2016, the implant was positioned at 3 mm above the crestal level. Then four models were designed with different crown retention systems: screw-retained (A), cement-retained (B), lateral-screw-retained (C), and modified lateral-screw-retained (D). The models were imported to the analysis software and mesh was generated based on the coincident nodes between the juxtaposed lines. For the boundary conditions, two loads (600 N) were applied (axial to the implant fixture and oblique at 30°) totaling 8 conditions according to retention design and loading. The von-Mises stress analysis showed that different retention systems modify the stress magnitude in the implant-supported posterior crown. There is a similar stress pattern in the implant threads. However, models C and D presented higher stress concentrations in the crown margin in comparison with A and B. The oblique loading highly increased the stress magnitude for all models. In the simulated conditions, part of the stress was concentrated at the lateral screw under axial loading for model C and oblique loading for model D. The results indicate a possible new failure origin for crown retained using lateral screws in comparison to conventional cement-retained or screw-retained systems.

Materials and Methods for All-Ceramic Dental Restorations Using Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) Technologies-A Brief Review.

The materials used in dentistry for the fabrication of all-ceramic restorations have undergone great and rapid developments over the last two decades. Among the most common ceramic materials in dentistry are those based on zirconium and lithium disilicate. Due to the properties of these materials, they are in great demand in the field of dental restoration production. Thus, dental restorations that will use those materials are commonly machined in CAD/CAM systems, which offer the possibility of manufacturing all-ceramic dental restorations in a very short period of time. This article reviews the modern materials in the field of all-ceramic dental restorations, their manufacturing processes, as well as what determines which ceramic materials are used for the production of CAD/CAM blanks and their production technology.

An Aesthetic and Economic Approach of Smile Designing for a Patient With Dentinogenesis Imperfecta: A Rare Case Entity.

This is a case report presenting a female patient in her twenties suffering from severely stained, unaesthetic, and worn-out teeth since her childhood. It was a major aesthetic and functional concern for her. This clinical presentation describes the prosthetic rehabilitation of a patient with generalized discolored and worn-out teeth to have enhanced aesthetics and masticatory function of the patient. This is a referred case of dentinogenesis imperfecta- II (DGI-II) from the Department of Oral Medicine and Radiology and Oral Pathology, as diagnosed by them after a thorough clinical, radiographical, and histopathological examination. DGI is a disorder of teeth characterized by discoloration and rapid wear and belongs to a group of disorders of the development of teeth. Due to the rapid wear and generalized intrinsically stained and discolored teeth, there is a loss of vertical dimension of occlusion (VDO) and an unesthetic look of the patient respectively. Therefore, the main objective of the case report is to re-establish the aesthetic and regain the VDO and functionality of the damaged teeth using the Pankey Mann Schuyler philosophy in which the first anterior teeth were rehabilitated with porcelain fused to metal (PFM) crowns based on aesthetics and phonetics of the patient. This was followed by posterior PFM crowns based on Broadrick's flag analysis for posterior occlusal plane determination and centric occlusion.

Dental ceramic damage associated with incorrect laboratory procedures.

Ceramic is a commonly used material in dentistry for reconstructing missing teeth or their tissues due to its biocompatibility, durability and excellent esthetic properties. Despite these advantages, the ceramic restoration damage remains a significant clinical problem. Its causes can be divided into clinical and laboratory factors. The most known include uneven occlusion, improper preparation, trauma, or parafunctions. This study focuses on characterizing less known laboratory causes of ceramic restoration damage. We reviewed the current literature available in the PubMed and Scopus databases. On the basis of 63 selected studies, 3 basic causes of damage were identified: excessive stresses between the framework and ceramic veneering, poor quality of the connection between the facing layer and the substructure, and defects resulting from the nature of the ceramic material such as defects in the ceramic layer, brittleness and lack of flexibility. The stages of the manufacturing process of various permanent ceramic restorations were presented. By controlling these procedures, we can eliminate the errors, resulting in long-term effective functioning of the ceramic restorations.

Prefabricated shouldered abutments enable successful restoration of molar crowns on implants.

PURPOSE: This retrospective study evaluated the effect of selected clinical and patient factors on survival, success, and peri-implant bone level changes of locking taper implants supporting molar crowns on Bicon's prefabricated shouldered abutments. METHODS: A total of 234 patients, who received 274 single molar crowns supported by locking taper implants were included in this retrospective study. Kaplan-Meier survival analysis was used to assess overall implant survival, prostheses survival, and success. Crowns were either monolithic (resin based) or bilayered (milled fiber-reinforced composite coping veneered with indirect composite). Early and late changes in marginal bone levels were plotted and analyzed with equivalence testing to compare the effects of different factors on crestal bone levels. RESULTS: At 9.5 years after implant surgery, the implant survival probability was 94.2%, the probability of prosthesis survival was 91.4%, and the probability of prosthetic success was 90.4%. Neither the use of different crown materials, nor the choice of monolithic versus bilayered crown construction, significantly affected the probability of prosthetic success. Marginal bone levels, on average, trended downwards towards the top of the implant within the first 2 years after functional loading, and remained stable on average, since then. Factors affecting bone levels included the use of nonsteroidal anti-inflammatory drugs, which precluded early implant bone loss; and subcrestal implant placement, which was linked to significantly higher long-term bone levels. CONCLUSION: The implant and abutment system studied resulted in high implant and prosthetic survival rates, regardless of prosthetic material used, with stable bone levels over time.

Shaping Smiles: A Narrative Review of Crown Advancements in Pediatric Dentistry.

This review examines the evolution of dental crowns in pediatric dentistry, highlighting the transition from traditional materials such as stainless steel to aesthetic and biocompatible alternatives like zirconia, resin-based composites, and Bioflex crowns. It focuses on their importance in repairing decayed or damaged teeth and improving children's oral health and psychological well-being. The methodology involved a comprehensive literature search over the past two decades, utilizing databases including PubMed, Google Scholar, and Chat.Consensus.App, with keywords related to pediatric dental crowns. The findings indicate that stainless steel crowns (SSCs) are valued for durability and cost-effectiveness, but they may cause hypersensitivity. Zirconia crowns are favored for biocompatibility, resistance, and aesthetics, although they are costlier and require more tooth reduction. Resin-based composite strip crowns offer a balance of aesthetics and function but have challenges in long-term stability. The review also touches on Bioflex crowns, noting their flexibility, but the limited research on their effectiveness. In summary, the review underscores the vital role of various dental crown materials in pediatric dentistry, stressing the importance of ongoing research to enhance clinical outcomes and pediatric patient quality of life. The selection of crown materials should consider efficacy, aesthetics, and the psychosocial effects on young patients.

A semi-selective medium to evaluate over-summering survival of Neopestalotiopsis sp. in Florida strawberry fields.

Devastating disease outbreaks with leaf spot symptoms and fruit rot caused by a fungus identified as a cryptic species of Neopestalotiopsis have generated concern in the Florida strawberry industry. Some Neopestalotiopsis species are saprobes in soil and plant debris, but the ability of the new Neopestalotiopsis sp. to survive in strawberry debris was unknown. Therefore, the objectives of this study were to develop a semi-selective medium for isolation of Neopestalotiopsis spp. and to evaluate Neopestalotiopsis sp. survival in soil and strawberry plant debris over summer in Florida. The Neopestalotiopsis semi-selective medium (NSM) inhibited growth of most fungal species pathogenic to strawberry in Florida, except Neopestalotiopsis rosae, Neopestalotiopsis sp., and Phomopsis obscurans, in addition to Penicillium spp., which is non-pathogenic. However, Neopestalotiopsis species, P. obscurans, and Penicillium spp. could be distinguished in the medium through morphological characteristics. Soil samples arbitrarily collected from six commercial fields towards the end of the season (May), and before (July) and after (September) pre-plant soil fumigation in the following season were processed with NSM and Neopestalotiopsis spp. populations were calculated as CFU/g soil. CFU ranged from 48.3 to 2410.8 at the end of the season and from 1.7 to 630.8 before soil fumigation, but Neopestalotiopsis spp. was not recovered after soil treatment. However, 1.7 to 25 CFU were obtained from the non-treated areas in the row middles. Neopestalotiopsis sp. survival was also evaluated on diseased strawberry plants (leaves and crowns) exposed to the environment for 17 months. On leaves, Neopestalotiopsis spp. was recovered for 6 months before leaf decomposition, whereas the number of CFU on crowns declined monthly but colonies were still recovered during the final evaluation months. HRM analysis confirmed most of the colonies from soil and crowns were the new Neopestalotiopsis sp. Our results show Neopestalotiopsis sp. can survive in strawberry debris under Florida summer conditions and may serve as a source of inoculum for the subsequent season.

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

BACKGROUND: 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. AIM: To evaluate and compare the fracture strength of four different types of dental crowns intended for paediatric patients. DESIGN: 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: 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. CONCLUSION: 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.

Initial bacterial adherence and biofilm formation on novel restorative materials used in paediatric dentistry.

OBJECTIVE: To evaluate the initial bacterial adherence and biofilm formation on novel restorative materials in paediatric dentistry and compare the results to stainless steel crown and primary enamel. MATERIALS AND METHODS: Twenty-five samples (Diameter = 4 mm) from five restorative materials (Tetric Power Fill light cured for 3 s or 10 s, Fuji II LC, Equia Forte HT Fil, Cention Forte, Stainless-steel crown) and primary enamel were prepared. Four samples served for recording of surface roughness (Ra) using a contact profilometer, 21 samples were incubated in stimulated human saliva for 2 h (initial bacterial adherence) and 72 h (biofilm formation) and served to determine ion releasing and bacterial growth. After 2 and 72 h, the number of colony-forming units (CFU) per ml was counted and expressed in Log10 CFU/ml. Data were analysed with two-way ANOVA and Tuckey's multiple comparisons test (p < 0.05). RESULTS: All tested materials showed similar initial bacterial adherence (p > 0.1). Stainless steel crown showed statistically significantly less biofilm formation than all other tested materials (p ≤ 0.02), except for Fuji II LC (p = 0.06). In terms of biofilm formation, the differences between all tested materials were not statistically significant (p ≥ 0.9). SIGNIFICANCE: Novel restorative materials in paediatric dentistry show similar initial bacterial adherence and biofilm formation. However, compared to other restorative materials, stainless steel crowns demonstrate the lowest level of biofilm formation. Ion-releasing materials may not necessarily show better antimicrobial properties than conventional materials.

Prolonged post-washing in ethanol decreases bond strength of additively manufactured crown materials.

OBJECTIVES: This study aimed to investigate the effect of post-washing duration and crown thickness on the bond strength between additively manufactured crown materials and dental cement in vitro. METHODS: Rectangular-shaped specimens of two thicknesses (1.5 and 2.0 mm) were additively manufactured from permanent VarseoSmile Crown (VC) and long-term temporary NextDent (ND) materials. The specimens were post-washed (n = 160) in ethanol for 5 min, 10 min, 1 h, and 8 h then cemented with dual-cure resin cement. Twenty PMMA (TC) were milled as a control. A chevron-notch test was performed to measure the maximum load until failure (N). Interfacial bond strength (J/m2) was calculated and statistically analysed. The mode of failure was analysed by scanning electron microscopy (SEM). RESULTS: There was a significant difference in the bond strength between all groups (p < 0.01). VC at 1.5mm thickness post-washed for 10 min showed the highest mean bond strength (1.77 ±0.96 J/m2) while VC at 2.0mm thickness post-washed for 8 h showed the lowest (0.22 ±0.10 J/m2). Exposure to ethanol for 8 h resulted in lower bond strength. Within the type of material, there were no differences in bond strength between the thicknesses when post-washed for the same duration. CONCLUSIONS: Prolonged post-washing of AM crown materials can significantly decrease the bond strength to resin cement. There were no differences between the permanent and long-term temporary AM materials. When post-washed for 5 min, AM materials observed comparable or higher bond strength values compared to PMMA. CLINICAL SIGNIFICANCE: The output of this research serves as a guide for dental practitioners, emphasising the importance of adhering to correct post-washing procedures for optimal bond strength of additively manufactured crown materials.

Full Mouth Rehabilitation for a Patient With Generalized Attrition: The Hobo Technique in Action.

This case report addresses the critical issue of severe tooth wear and its impact on the vertical dimension of occlusion in a 75-year-old patient. The patient presented with worn-down teeth, chewing difficulties, and aesthetic concerns, prompting a comprehensive treatment plan utilizing the Hobo twin-stage technique. The approach involved careful diagnosis, root canal therapy, and the creation of provisional restorations, monitored through an occlusal splint. The prosthetic phase incorporated strategically designed porcelain-fused-to-metal crowns, aiming for optimal tooth alignment and balanced movement. The successful outcome not only restored function and aesthetics but also enhanced the patient's confidence. This case underscores the effectiveness of a systematic approach in managing severe tooth wear, emphasizing the importance of regular follow-ups and good oral hygiene for long-term success.