Effect of Different Isolation Methods on Bioaerosol Distribution: An In Vitro Study.

Purpose: The purposes of this in vitro study were to evaluate the effect of three isolation methods to mitigate bioaerosols during stainless steel crown (SSC) preparations and assess the distribution of Streptococcus mutans by aerosolization in closed-room operatories. Methods: Melamine teeth coated in laboratory-grown S. mutans biofilm were prepared for SSCs using three different isolation methods. Agar plates were placed in five locations throughout the operatory and opened during each preparation as well as for 10 minutes immediately following to collect aerosolized S. mutans. Bacterial colonies were counted after incubating plates for 48 hours. Data were analyzed for differences between the isolation method and plate locations. Results: Bacterial colony counts for teeth prepared using high-volume evacuation suction (HVE) with dental dam (DD) isolation were statistically significantly higher than for those prepared using HVE with a DryShield®(DS) and HVE with no isolation at the assistant (A) (P<0.001), operator face shield (FS) (P<0.001), and patient (Pt) (P=0.002) locations. No significant differences were found among isolation methods for parent (Pa) or rear delivery (RD) locations. The location that produced the most bacterial colony counts using HVE with DD isolation was FS (P<0.001), followed by A (P=0.04), Pt (P<0.001), and RD and Pa (P<0.001). Counts produced from teeth prepared with DS isolation were significantly higher at the Pt location than the A (P<0.001), FS (P=0.002), RD (P<0.001), and Pa (P=0.008) locations. Conclusion: The use of dental dam with high-volume evacuation suction during stainless steel crown preparations increased bioaerosols near the procedure, while dental evacuation systems (DryShield®) may effectively limit their spread.

Effect of margin designs and loading conditions on the stress distribution of endocrowns: a finite element analysis.

BACKGROUND: Margin designs and loading conditions can impact the mechanical characteristics and survival of endocrowns. Analyzing the stress distribution of endocrowns with various margin designs and loading conditions can provide evidence for their clinical application. METHODS: Three finite element analysis models were established based on the margin designs: endocrown with a butt-joint type margin (E0), endocrown with a 90° shoulder (E90), and endocrown with a 135° shoulder (E135). The E0 group involved lowering the occlusal surface and preparing the pulp chamber. The E90 group created a 90° shoulder on the margin of model E0, measuring 1.5 mm high and 1 mm wide. The E135 group featured a 135° shoulder. The solids of the models were in fixed contact with each other, and the materials of tooth tissue and restoration were uniform, continuous, isotropic linear elasticity. Nine static loads were applied, with a total load of 225 N, and the maximum von Mises stresses and stress distribution were calculated for teeth and endocrowns with different margin designs. RESULTS: Compared the stresses of different models under the same loading condition. In endocrowns, when the loading points were concentrated on the buccal side, the maximum von Mises stresses were E0 = E90 = E135, and when there was a lingual loading, they were E0 < E90 = E135. In enamel, the maximum von Mises stresses under all loading conditions were E0 > E90 > E135. In dentin, the maximum von Mises stresses of the three models were basically similar except for load2, load5 and load9. Compare the stresses of the same model under different loading conditions. In endocrowns, stresses were higher when lingual loading was present. In enamel and dentin, stresses were higher when loaded obliquely or unevenly. The stresses in the endocrowns were concentrated in the loading area. In enamel, stress concentration occurred at the cementoenamel junction. In particular, E90 and E135 also experienced stress concentration at the shoulder. In dentin, the stresses were mainly concentrated in the upper section of the tooth root. CONCLUSION: Stress distribution is similar among the three margin designs of endocrowns, but the shoulder-type designs, especially the 135° shoulder, exhibit reduced stress concentration.

Transfer of Guided Emergence Profile Developed Using Customized Provisional Implant Restoration and Cementation Using an Abutment Replica Technique: A Case Report.

The long-term success of dental implants depends not only upon implant osseointegration, but also on the surrounding soft tissue health and profile. An ideal emergence profile contributes to the aesthetics of an implant restoration. It maintains long-term implant health by preventing potential food accumulation and forming a barrier against bacterial ingress. This article describes a method for obtaining an impression of implants that will capture the custom guided peri-implant soft tissue contours accurately, thus contributing to a final restoration with favorable aesthetics. We also describe a technique for reducing excess cement in a cement retained implant crown, thereby contributing to the health of the peri-implant tissues.

Immediate Loading Using the Digitalized Customized Restoration of Single-tooth Implants Placed in Fresh Extraction Sockets in the Aesthetic Anterior Maxilla: A 10-Year Prospective Study of Marginal Bone Level.

AIM: The objective of this study was to assess marginal bone level around single implants inserted in fresh extraction sockets in the anterior maxillary region and instantly restored with computer-aided design/computer-aided manufacturing customized temporary crowns cemented on the final abutment. MATERIALS AND METHODS: A total of 20 patients (15 females and 5 males, with a mean age of 30 years), where 20 were placed in fresh extraction sockets. After raising a full-thickness flap, atraumatic extraction was performed the implant site was prepared and fixtures were stabilized on the palatal bone wall. The implant location was immediately transmitted to the prepared master model using the pick-up impression coping seated in the surgical guide template. Prefabricated abutments were used as the final abutment on the master model, scanned and the crown was planned using computer-aided manufacturing customized software. Later on 8th weeks, abutments were torqued as per the manufacturer's recommendation, and the final crowns were cemented. Using personalized intraoral radiographs marginal bone level was evaluated mesially and distally to the implant shoulder as a reference at implant placement, 8 weeks, 1, 3, 5, and 10 years after loading. RESULTS: Wholly implants were osteo-integrated positively after 10 years of practical loading, but only 18 were available for clinical and radiological follow-up, and 2 patients with two implants were excluded from the study due to relocation abroad without any implant failure. The average marginal bone loss (MBL) in the current report was 0.16 ± 0.167 mm at crown cementation, 0.275 ± 0.171 mm after 1 year, 0.265 ± 0.171 mm after 3 years, 0.213 ± 0.185 mm after 5 years, and 0.217 ± 0.194 mm at 10 years. CONCLUSION: The strategy of inserting and not removing the final abutment at the time of implant placement facilitates the establishment of adequate attachment of both soft and hard tissues to the abutment surface, ensuring uninterrupted organization of tissue architecture and offers advantages in helping maintain soft tissue maturation and preventing marginal bone level. CLINICAL SIGNIFICANCE: Immediately loaded implants in freshly extracted sockets lead to a significant reduction in marginal ridge resorption. The use of a temporary crown on a prefabricated abutment, exclusive of successive abutment manipulation, proved effective in preserving the primarily founding blood clot and served as a prototype for shaping the soft tissue around the previously wounded gum. How to cite this article: Berberi A, El Zoghbi A, Aad G, et al. Immediate Loading Using the Digitalized Customized Restoration of Single-tooth Implants Placed in Fresh Extraction Sockets in the Aesthetic Anterior Maxilla: A 10-Year Prospective Study of Marginal Bone Level. J Contemp Dent Pract 2024;25(3):213-220.

Transferring emergence profile and position of interim restorative implant fixture. A novel digital technique.

The present technical article describes a protocol to digitally reproduce the emergence profile of an interim implant prosthesis (IP) and to transfer its macrogeometry into the definitive restoration. The purpose of this protocol was to minimize alterations in the gingival architecture developed during the interim restorative phase of a single implant that could potentially jeopardize its esthetic outcome. The process included obtaining an intraoral scan with the interim IP in situ, a duplicate of this intraoral scan that was used to capture the exact position of the implant, and an extraoral scan of the prosthesis. These data could then be imported into IOS software to create a model where the patients' soft tissue was incorporated with precision, allowing for the fabrication of a definitive crown with an optimal soft tissue adaptation. As there are few articles in the scientific literature that have reported a consistent method to replicate the emergence profile of an interim IP, the present technical article aims to highlight the potential of utilizing the emergence profile of an interim IP created by IOS software.

The biologically oriented preparation technique (BOPT) approach for preventing gingival recessions in fixed prosthodontics. A 5- to 13-year follow-up retrospective study.

AIM: The present study was a retrospective medium- to long-term follow-up assessment of the clinical outcomes of patients rehabilitated with fixed prostheses according to the biologically oriented preparation technique (BOPT) principles. MATERIALS AND METHODS: Clinical records of patients rehabilitated between January 2007 and December 2014 were retrospectively assessed. Patients whose records met the inclusion criteria were also recalled for a hygiene visit. Data analyzed included the patients' periodontal condition, the presence of gingival recessions as well as any technical or biologic prosthetic complication. RESULTS: Fifty-eight patients were recalled; of these, 52 patients who had received 220 crowns were available for the evaluation (the dropout being 13.8%). The average follow-up was 9.3 years (range 5 to 13 years): 14 patients (114 prosthetic crowns) had a follow-up between 5 and 8 years, and 36 patients (106 prosthetic crowns) between 9 and 13 years. The prosthetic survival rate was 99.6%. One radicular fracture (0.4%) and four chippings of the veneering porcelain (1.8%) were recorded. Six teeth (2.7% of the examined prosthetic crowns) presented gingival recession of < 1 mm, and 13 teeth (24 sites) had a pocket probing depth of 4 mm (5.9% of the prosthetic crowns/1.8% of the sites). Finally, 20 sites (1.5%) in seven teeth (3.2%) showed bleeding on probing. CONCLUSIONS: Tooth preparation according to the BOPT principles (ie, with a vertical finishing line) resulted in medium- to long-term periodontal health and stability of the gingival tissue, and prosthetic success was maintained.

Potential factors affecting the success rate of indirect pulp therapy in primary molars with deep caries: a retrospective study.

Indirect pulp therapy (IPT) is a common conservative treatment for deep dental caries. However, the potential risk factors for the prognosis of IPT have not been well studied. This study retrospectively investigated the success rate of IPT in treating primary molars with deep caries and the factors potentially affecting the two-year success rate. A total of 303 primary molars in 202 children (106 boys and 96 girls) were included in this study. These primary molars were identified as having deep caries by clinical and radiographic examinations and were treated with IPT. The factors potentially affecting the IPT success rate were analyzed after two years of follow-up. The results indicated that the two-year IPT success rate was 86% (262/303). The success rate of primary molars with and without stainless steel crowns was 96% (120/125) and 80% (142/178), respectively. Primary molars treated with stainless steel crowns showed a significantly lower risk of failure (hazard ratio (HR) = 0.18, 95% confidence interval (CI): (0.10, 0.34), p = 0.01). There were no significant differences in other factors, including gender (male vs. female), age (preschool vs. school age), cooperation level (Frankl 2 vs. 3 or 4 scales), arch type (maxillary vs. mandibular), tooth type (first vs. second primary molar), or pulp capping material (calcium hydroxide vs. glass ionomer cement). IPT is an effective, conservative treatment modality for primary molars with deep caries. Stainless steel crowns could significantly improve the IPT success rate.

Vitamin D deficiency and chronological hypoplasia with hypomineralisation: a case report.

Patients being reported for vitamin D deficiency (VDD) are increasing, particularly among the children and adolescents. This study aims to manifest the clinical and dental evaluations of a child with VDD, referred to the dental office. A 10-year-old British Asian boy was referred to the paediatric specialist dentistry clinic by the general dentist for dental management. The medical history depicted that the patient was diagnosed with VDD, secondary hyperparathyroidism and delayed growth. Moreover, his mother had the VDD during pregnancy. The patient was breast fed and had rickets in infancy. He was prescribed vitamin D supplements at the age of 16 months. He had received multiple dental treatments under local anaesthesia but with limited cooperation. Clinical examination revealed that the patient had chronological enamel hypoplasia shown as bands at the occlusal third on specific teeth. Suboptimal hygiene with general plaque induced gingivitis, dental caries in permanent and primary teeth, and delayed the teeth eruption. Preventions included appropriate oral hygiene and dietary advice, fluoride varnish application and fissure sealant placement. The treatments included anterior direct composite restoration, posterior composite restoration, stainless steel crowns and extractions. Thorough medical history is essential to understand the underlying causes of dental defects. Early dental intervention can restore the patient appearance and function and prevent further dental damage.

Comparison of three-dimensional printed resin crowns and preformed stainless steel crowns for primary molar restorations: a randomized controlled trial.

The importance of aesthetics in children has increased over time. Therefore, this multicenter randomized clinical trial aimed to analyze and compare three-dimensional (3D)-printed resin crowns (RCs) as a potential alternative to stainless-steel crowns (SSCs) for restoring primary molars with extensive carious lesions. According to the null hypothesis, no statistically significant difference was observed in restoration failure between RC and SSC groups. A total of 56 primary molars after pulp treatment at two dental hospitals were included. After pulp treatment, the teeth were randomly divided into two groups: SSCs (n = 28) and RCs (n = 28). At 1 week and 3, 6 and 12 months, the Quigley-Hein plaque index (QHI), gingival index (GI), occlusal wear, and survival rate were assessed by examination, radiography and alginate impressions. No significant difference in QHI was observed between the two groups. However, the GI at 12 months and occlusal wear in the RC group were significantly higher than those in the SSC group (p < 0.05). The survival rates were 100% in the SSC group and 82.1% in the RC group (p = 0.047). Cracks and discoloration were also observed in the RCs. Within the limitations of this study, 3D-printed RCs are aesthetically superior to SSCs and clinically easy to repair. However, if clinical effectiveness and safety are improved, RCs could potentially become a viable aesthetic alternative in the future.

The fracture resistance of pulpotomized primary molars restored with zirconia crowns, lithium disilicate or resin based ceramic endocrowns.

BACKGROUND: Endocrown in pediatric dentistry was rooted in the fundamental principles of preserving healthy dental tissues, leveraging contemporary adhesive methodologies. AIM: This research aimed on assessing and comparing the fracture resistance of pulpotomized primary molars when rehabilitated with zirconia crowns and two distinct types of endocrowns, namely E-Max and Brilliant Crios. METHODS: The study involved thirty, anonymized, freshly extracted second primary molars that underwent pulpotomy. These teeth were then evenly divided into three groups, each consisting of ten specimens: the zirconia crown, the E-Max endocrown, and the Brilliant Crios endocrown groups. Post-pulpotomy, the teeth were prepared for their respective restorations. Subsequent to this preparation, the zirconia crowns, E-Max endocrowns, and Brilliant Crios endocrowns were secured. To evaluate the fracture resistance using a computer-controlled testing machine (Instron), a progressively increasing load was applied to each group until fracture occurred. The gathered data were then analyzed for outliers and subjected to normality testing using the Shapiro-Wilk and/or Kolmogorov-Smirnov tests, with a significance threshold set at 0.05. RESULTS: There was no statistically significant difference in fracture resistance of pulpotomized primary molars among lithium disilicate (E-Max) group (mean=1367.59N), Brilliant Crios group (mean=1349.73N) and zirconia group (mean=1240.82N). CONCLUSION: Endocrowns can be considered a promising restoration for pulpotomized primary molars.

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

AIM: 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. MATERIALS: 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]. CONCLUSION: 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.

Effects of 3D-Printing Technology and Cement Type on the Fracture Resistance of Permanent Resin Crowns for Primary Teeth.

PURPOSE: To evaluate the fracture resistance of permanent resin crowns for primary teeth produced using two different 3D-printing technologies (digital light processing [DLP] and stereolithography [SLA]) and cemented with various luting cements (glass ionomer, resin-modified glass ionomer, and self-adhesive resin cement), whether thermally aged or not. MATERIALS AND METHODS: A typodont primary mandibular second molar tooth was prepared and scanned, and a restoration design was created with web-based artificial intelligence (AI) dental software. A total of 96 crowns were prepared, and 12 experimental groups were generated according to the cement type, 3Dprinting technology (DLP or SLA), and thermal aging. Fracture resistance values and failure types of the specimens were noted. The results were statistically analyzed with three-way ANOVA and Tukey HSD tests (α = .05). RESULTS: The results of the three-way ANOVA showed that there was an interaction among the factors (3D-printing technology, cement type, and thermal aging) (P = .003). Thermal aging significantly decreased the fracture resistance values in all experimental groups. DLP-printed crowns showed higher fracture resistance values than SLA-printed crowns. Cement type also affected the fracture resistance, with glass ionomer cement showing the lowest values after aging. Resin-modified glass ionomer and resin cements were more preferable for 3D-printed crowns. CONCLUSIONS: The type of cement and the 3D-printing technology significantly influenced the fracture resistance of 3D-printed permanent resin crowns for primary teeth, and it was decided that these crowns would be able to withstand masticatory forces in children.

Comparison of the Flexural Strength of Three Different Aged and Nonaged 3D-Printed Permanent Crown Resins.

AIM: The aim of this study was to evaluate the flexural strength properties of three different aged and nonaged 3D-printed resins built by different 3D printing systems used in dental applications. MATERIALS AND METHODS: Bars (2 × 2 × 25 mm) were additively fabricated using a 3D printer and different dental crown resins (Saremco Crowntec, Senertek P-Crown V2, and Senertek P-Crown V3) per the manufacturers' recommendations. Each subgroup was divided into aged and nonaged subgroups (n = 10 bars per group). Thermocycling procedures (5° to 55°C; 5,000 cycles) were performed under favorable conditions for the aged subgroups from each material. Flexural strength (MPa) was measured in all samples using a universal test machine. RESULTS: When both aged and nonaged resins are compared, significant differences were found in flexural strength measurements (P < .001). The highest flexural strength was observed in the Saremco Crowntec group, while the lowest flexural strength was observed in the Senertek P Crown V2 group. The flexural strength measurements of Saremco Crowntec and Senertek P Crown V3 displayed no significant difference between their aged and nonaged groups (P > .05), while Senertek P Crown V2 (P = .039) showed significant differences between its aged and nonaged groups. CONCLUSIONS: Saremco Crowntec showed the highest flexural strength both in aged and nonaged groups, while Senertek P Crown V2 had the lowest strength. The artificial aging process decreased flexural strength values in all 3D-printed resin groups.

Manufacturing Accuracy, Intaglio Surface Adaptation, and Survival of Additively and Subtractively Manufactured Definitive Resin Crowns After Cyclic Loading: An In Vitro Study.

PURPOSE: To assess the manufacturing accuracy, intaglio surface adaptation, and survival of resin-based CAD/CAM definitive crowns created via additive manufacturing (AM) or subtractive manufacturing (SM). MATERIALS AND METHODS: A maxillary right first molar crown was digitally designed and manufactured using AM hybrid resin composite (VarseoSmile Crown Plus, Bego [AM-HRC]), AM glass filler-reinforced resin composite (Crowntec, Saremco Dental [AM-RC]), and SM polymer-infiltrated ceramic (Vita Enamic, VITA Zahnfabrik [SM-PICN]). Manufacturing accuracy (trueness and precision) was assessed by computing the root mean square (RMS) error (in µm; n = 15 per material). Intaglio surface adaptation was assessed by calculating the average gap distance (µm). Ten crowns from each group were cemented on fiberglass-reinforced epoxy resin dies and cyclically loaded to simulate 5 years of functional loading. One-way ANOVA, post hoc Bonferroni comparison tests, and Levene's test were used to analyze the data (α = .05). RESULTS: AM-RC had higher overall trueness than AM-HRC and SM-PICN (P ≤ .05), whereas the trueness of AM-RC on the external surface was similar to that of SM-PICN (P = .99) and higher than AM-HRC (P = .001). SM-PICN had lower precision than AM-RC and AM-HRC overall and at internal occlusal surfaces (P ≤ .05). Overall intaglio surface adaptation was similar between all groups (P = .531). However, for the axial intaglio surface, AM-RC and AM-HRC had higher adaptation than SM-PICN (P ≤ .05). All tested crowns survived the cyclic loading simulation of 5 years clinical use. CONCLUSIONS: AM-RC showed high manufacturing accuracy and adaptation. The tested resin-based CAD/CAM materials demonstrated clinically acceptable manufacturing accuracy and simulated medium-term durability, justifying the initiation of clinical investigations to determine their potential implementation in daily clinical practice.

Positional Trueness with Different Titanium Base Bonding Techniques for Single Implant Crowns: In Vitro Evaluation of Model-Free Workflow Versus Additively Manufactured Models.

OBJECTIVES: To compare the positional trueness of implant-crown bonding to titanium bases (Ti-bases) using different bonding protocols. MATERIALS AND METHODS: A nonprecious alloy model with a single implant at the mandibular right first molar site was digitized, then a single implant crown was designed. The crown was milled, adhesively cemented on a Ti-base, and screw-retained on the implant in the master model to obtain a reference scan. Forty PMMA implant crowns were subtractively manufactured and allocated to one of four study groups (n = 10 crowns per group) based on the bonding protocol on Ti-bases: Group 1 = modelfree bonding; Group 2 = bonding on the master model (control); Group 3 = bonding on a model from an industrial-grade 3D printer (Prodways); Group 4 = bonding on a model from a conventional 3D printer (Asiga). To assess the positional trueness of crowns, the scans of crowns when on the model were superimposed over the reference scan. Median distance and angular deviations were analyzed using Kruskal-Wallis and Mann- Whitney tests (α = .05). Mesial and distal contacts of crowns were assessed by two independent clinicians. RESULTS: The control group (Group 2) resulted in the smallest distance deviations (0.30 ± 0.03 mm) compared to model-free (0.35 ± 0.02 mm; P = .002; Group 1) and conventional 3D printer (0.37 ± 0.01 mm; P = .001; Group 4) workflows. Buccolingual (P = .002) and mesiodistal (P = .01) angular deviations were higher in the conventional 3D printer group than in the control group (P = .002). Proximal contact assessments did not show any differences among groups. CONCLUSIONS: While bonding crowns to Ti-bases on a master model created with an industrial-grade 3D printer resulted in the highest positional trueness, model-free workflows had a similar positional trueness to those manufactured with a conventional 3D printer.

Maximum Fracture Load of Interim Crowns Fabricated by Additive and Subtractive Techniques.

PURPOSE: To evaluate fracture load values of five types of interim CAD/CAM crowns with and without thermocycling. MATERIALS AND METHODS: A complete coverage crown was designed on a mandibular first molar with a uniform 1.5-mm axial and occlusal reduction, and the STL file was exported to manufacture 100 crowns using five materials (20 crowns per material): ZCAD Temp Esthetic (SM-ZCAD; Harvest Dental); Telio CAD (SM-TCAD); P pro Crown and Bridge (AM-PPRO); E-Dent 400 C&B MHF (AM-EDENT); and DENTCA Crown & Bridge (AM-DENTCA). Each group was then divided into two subgroups: before and after thermocycling (10 cornws per subgroup). The STL file of the mandibular first molar die was used to manufacture 100 resin dies. Each die was assigned to one interim crown. Interim crowns were then luted to their assigned die using a temporary luting agent. The fracture strength of crowns was then assessed using a universal testing machine at a crosshead speed of 2 mm/minute. Two-way ANOVA followed by Tukey multiple comparations post-hoc tests were used to assess the effect of material choice and thermocycling process on the fracture strength of interim crowns (α = .05). RESULTS: Material choice and the thermocycling process exerted a significant (P < .001) impact on the fracture strength of interim crowns. However, the interaction between these two factors did not yield a statistically significant effect (P = .176). CONCLUSIONS: Within the limitations of this study, the type of interim materials and thermocycling process have a significant impact on the fracture strength of interim crowns.

A conservative approach to localize loose implant screw through cemented crown: an in vitro experimental study.

BACKGROUND: Retrieval of cement-retained implant-supported restorations is intriguing in cases of screw loosening. Detecting the estimated size of the screw access hole (SAH) could decrease destruction to the prosthesis and preserve the crown. OBJECTIVES: To precisely localize loose implant screws through cemented crowns to reduce crown damage after screw loosening. MATERIALS AND METHODS: In this in vitro study, 60 cement-retained implants supported 30 zirconia-based, and 30 ceramics fused to metal (CFM) lower molar crowns were invented, and each was subdivided into three subgroups (10 each). In group I (AI/BI) (control), SAH was created with the aid of orthopantomography (OPG). In contrast, in group II (zirconia-crown), SAH was created with the aid of CBCT + 3D printed surgical guide with a 2 mm metal sleeve in subgroups IIA/IIIA and CBCT + MAR was used to develop SAH in subgroups IIB/IIIB. SEM and Micro-CT scanned the SAH openings to determine the diameter of the hole, cracking, chipping, and chipping volume. RESULTS: Regarding the effect of plane CBCT and CBCT + MAR on prepared crowns, a highly significant association between group I with group II (p = 0.001) and group III (p = 0.002) was detected. Regarding the cracking of SAH, significant differences between the zirconium crown and CFM restoration (p = 0.009) were found, while for the chipping, no significant association was seen between groups (p = 0.19). CONCLUSIONS: CBCT, either as a plane CBCT or with MAR, significantly improved the accuracy of drilling the screw channel and decreased injury to the existing restoration and abutment, aiding in better localization of SAH in loosened implant abutment screws.

Diagnostic accuracy of artificial intelligence versus manual detection in marginal bone loss around fixed semicolon. a systematic review.

Objectives: The aim of the review is to evaluate the existing precision of artificial intelligence (AI) in detecting Marginal Bone Loss (MBL) around prosthetic crowns using 2-Dimentional radiographs. It also summarises the recent advances and future challenges associated to their clinical application. Methodology: A literature survey of electronic databases was conducted in November 2023 to recognize the relevant articles. MeSH terms/keywords were used to search ("panoramic" OR "pantomogram" OR "orthopantomogram" OR "opg" OR "periapical") AND ("artificial intelligence" OR "deep" OR "machine" OR "automated" OR "learning") AND ("periodontal bone loss") AND ("prosthetic crown") in PubMed database, SCOPUS, COCHRANE library, EMBASE, CINAHL and Science Direct. RESULTS: The searches identified 49 relevant articles, of them 5 articles met the inclusion criteria were included. The outcomes measured were sensitivity, specificity and accuracy of AI models versus manual detection in panoramic and intraoral radiographs. Few studies reported no significant difference between AI and manual detection, whereas majority demonstrated the superior ability of AI in detecting MBL. CONCLUSIONS: AI models show promising accuracy in analysing complex datasets and generate accurate predictions in the MBL around fixed prosthesis. However, these models are still in the developmental phase. Therefore, it is crucial to assess the effectiveness and reliability of these models before recommending their use in clinical practice.

A randomized controlled clinical trial on press and block lithium disilicate partial crowns: A 4-year recall.

PURPOSE: To evaluate clinical performances of two lithium disilicate systems (Initial LiSi press vs Initial LiSi Block, GC Co.) using modified United States Public Health Service (USPHS) evaluation criteria and survival rates after 4 years of clinical service. METHODS: Partial adhesive crowns on natural abutment posterior teeth were made on 60 subjects who were randomly divided into two groups: Group 1: Initial LiSi press and Group 2: Initial LiSi Block. Fabrication of partial crowns was made with full analog and digital procedure in Groups 1 and 2 respectively. The restorations were followed-up for 1 and 4 years, and the modified USPHS evaluation was performed at baseline and each recall together with periodontal evaluation. Contingency tables to assess for significant differences of success over time in each group and time-dependent Cox regression to test for differences between the two groups were used and the level of significance was set at P< 0.05. RESULTS: Regarding modified USPHS scores, all evaluated parameters showed Alpha or Bravo and no Charlie was recorded. No statistically significant difference emerged between the two groups in any of the assessed variables (P> 0.05). No statistically significant difference between scores recorded at the baseline and each recall. All modified USPHS scores were compatible with the outcome of clinical success and no one restoration was replaced or repaired, and the survival rate was 100% after 4 years of clinical service. No difference was found between traditional and digital procedure to fabricate the crowns. The two lithium disilicate materials showed similar results after 4 years of clinical service. CLINICAL SIGNIFICANCE: The crowns made with the two tested lithium disilicate materials with analog and digital procedures showed 100% survival after 4 years of clinical service with no statistically significant difference using the modified USPHS scores.