A comparative study of the use of digital technology in the anterior smile experience.

OBJECTIVES: this study aims to compare the clinical outcomes of traditional and digital crown extension guides in the aesthetic restoration of anterior teeth. Additionally, the study will analyze the differences in the results of various digital crown extension guides in anterior aesthetic restorations. METHODS: Sixty-two patients who required aesthetic restoration of their anterior teeth were selected for this study. The patients had a total of 230 anterior teeth and were randomly divided into three groups: a control group of 22 cases who received diagnostic wax-up with pressure film, an experimental group 1 of 20 cases who received 3D printed digital models with pressure film, and an experimental group 2 of 20 patients who received digital dual-positioning guides. The control group had a total of 84 anterior teeth, experimental group 1 had 72 anterior teeth, and experimental group 2 had 74 anterior teeth. The study compared three methods for fabricating crown extension guides: the control group used the diagnostic wax-up plus compression film method, while experimental group 1 used compression film on 3D printed models and experimental group 2 used 3D printed digital dual-positioning crown extension guides. After the crown lengthening surgery, the control group patients wore DMG resin temporary crown material for gingival contouring, while the experimental group patients wore 3D printed resin temporary crowns for the same purpose. The patients were followed up in the outpatient clinic after wearing temporary crowns for 1 month, 3 months, and 6 months, respectively. The clinical results were evaluated in terms of marginal fit, red aesthetic index, and white aesthetic index. RESULTS: Based on the statistical analysis, the experimental group required significantly fewer follow-up visits and less time for guide design and fabrication compared to the control group. Additionally, the surgical time for the experimental group was significantly shorter than that of the control group. During the postoperative period between the 1st and 3rd month, the PES index scores for the marginal gingival level, proximal, and distal mesiodistal gingival papillae of the experimental group showed a trend of superiority over those of the control group. By the 6th month, the marginal gingival level exhibited a significant difference between the experimental and control groups. The experimental group demonstrated superior results to the control group in terms of shape, contour, and volume of the teeth, color, surface texture, and transparency of the restorations, and features during the 1st and 3rd postoperative months. In the 6th month, the comparative results indicated that the experimental group continued to exhibit superior outcomes to the control group in terms of the shape, color, surface texture, and transparency of the restorations, as well as the characteristics of the teeth. Additionally, the experimental group demonstrated significantly fewer gingival alterations than the control group at 1 month, 3 months, and 6 months post-procedure, with this difference being statistically significant. Furthermore, the combination of 3D printing technology and restorative techniques was utilized, resulting in consistent patient satisfaction. CONCLUSION: Digitalisation plays an important role in anterior aesthetic restorations. The use of digital technology to manage the entire process of anterior cosmetic restorations can improve restorative results, reduce the number of follow-up appointments, shorten consultation time, and achieve better patient satisfaction.

One case of complicated crown root fracture of upper anterior teeth managed by multidisciplinary joint approaches.

Complicated crown root fracture is a serious combined fracture of the enamel, dentin, and cementum in dental trauma. The treatment method is complicated. During the procedure, the condition of pulp, periodontal, and tooth body should be thoroughly evaluated, and a multidisciplinary approach combined with sequential treatment is recommended. This case reported the different treatment and repair processes of one case of two affected teeth after complicated crown root fracture of upper anterior teeth, including regrafting of broken crown after flap surgery at the first visit, direct resin repair to remove broken fragments, and pulp treatment and post-crown repair at the second visit. After 18 months of follow-up, the preservation treatment of the affected teeth with complicated crown root fracture was achieved. Therefore, fragment reattachment and post-crown restoration are feasible treatment options for children with complicated crown root fracture.

Comparative evaluation of clinical success of Stainless Steel and Bioflx crowns in primary molar - A 12 month split mouth prospective randomized clinical trial.

PURPOSE: The purpose of this clinical trial was to assess and compare the clinical outcomes of Bioflx crowns (BFCs) with stainless steel crowns (SSCs) in primary molars (PMs). MATERIALS AND METHODS: This prospective split-mouth randomized controlled clinical trial was conducted between March 2022 and June 2023. Thirty-eight patients (17 females and 21 males) with a mean age of 5.21 years participated in this study. Each child (n = 38) received both SSC and BFC. Clinical and radiographic follow-up was performed at baseline, 3, 6, and 12 months using the modified United States Public Health System scoring criteria to evaluate various parameters. RESULTS: At the 3 and 6 months' follow-up, no significant difference was observed between the two groups. However, at 1-year follow-up, a statistically significant difference (P < 0.05) was evident in the frequency between the two groups for the criteria of crown retention after cementation and anatomic form of the crown, indicating a preference for SSC over prototype 1 BFC. CONCLUSION: The 12-month results indicate that BFC performed similarly to the established SSC for the restoration of PMs providing better esthetics.

[Evaluation of the effect of MTF-S on the removal of impacted mandibular wisdom teeth with complete or partial crown impaction].

PURPOSE: To evaluation the effect of modified triangular flap-secondary healing (MTF-S) on the treatment of mandibular impacted wisdom teeth with full or partial bone impaction. METHODS: A total of 207 patients with mandibular impacted wisdom teeth were selected in Shaoxing Stomatological Hospital from June 2022 to June 2023. Among them, 86 patients had completely impacted wisdom teeth (group A), and 121 patients had partially impacted wisdom teeth (group B). All patients had bilateral impacted wisdom teeth. One of the wisdom teeth was removed first and was sutured with triangular flap-primary healing (TF-P). The other wisdom tooth was removed two weeks later and was sutured with MTF-S. Patients in groups A and B were divided into two subgroups based on suture methods, with TF-P used for group A1 and B1, and MTF-S used for groups A2 and B2. Perioperative indicators, including surgical time, root loss rate, and completeness of extraction sockets were recorded; Postoperative complications of four groups, including pain, swelling, and limited mouth opening were compared. SPSS 22.0 software package was used for statistical analysis. RESULTS: The surgical time of group A1, A2, B1 and B2 was (17.69±3.28), (18.22±3.06), (12.37±3.72) and (12.64±4.13) minutes, respectively. The surgical time of group A1 and A2 was significantly longer than that of group B1 and B2 (P＜0.05). Seven days after surgery, the VAS scores of group A1, A2, B1 and B2 were (1.17±0.34), (0.93±0.29), (0.48±0.15) and (0.76±0.21), respectively. The VAS scores of group B1 and B2 were lower than those of group A1 and A2, and group A2 was lower than group A1 and B2 was higher than group B1 group(P＜0.05). On the 1st day, 3rd day, and 7th day after surgery, the swelling degree in group A1 was greater than that in group B1, and the swelling degree in group B1 was greater than that in group A2 and B2(P＜0.05); while the limitation of mouth opening mouth in group A2 and B2 was lower than that in group A1 and B1, and the limitation of opening mouth in group B2 was lower than that in group A2(P＜0.05). CONCLUSIONS: Compared with partially impacted wisdom teeth, the extraction of completely impacted wisdom teeth has a longer surgical time. For completely impacted wisdom teeth, MTF-S is beneficial for reducing postoperative pain, swelling and mouth opening limitations. For partially impacted wisdom teeth, MTF-S is beneficial for reducing postoperative swelling and mouth opening limitations, but the effect is not significant in reducing patient pain.

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.

The stress distribution of a primary molar tooth restored with stainless steel crown using different luting cements.

BACKGROUND: The aim of this study is to evaluate the stress distributions of a primary molar tooth restored with a stainless steel crown (SSC) using resin and glass ionomer luting cements by Finite Element Analysis (FEA). METHODS: Original DICOM data of a primary molar was used to create a 3D model. One model was prepared as a tooth model with SSC. A 30 µm cement layer was used in model. Two different luting cements were tested in the study: self-cure adhesive resin cement, and glass ionomer cement. Vertical and oblique loads of 330 N were applied to simulate maximum bite force and lateral forces in the occlusal contact areas of the models. Maximum von Mises stress values in the models were evaluated as MPa. RESULTS: The maximum von Mises stress value was observed in the force application and general occlusal contact areas for all models. The maximum von Mises stress values were higher in the tooth model with SSC using self-cure adhesive resin cement (478.09 MPa and 214.62 MPa) than in the tooth model with SSC using glass ionomer cement (220.06 MPa and 198.72 MPa) in both vertical and oblique loading, respectively. CONCLUSIONS: Depending on the magnitude of the bite force on the SSC, fracture of the luting cement materials could occur if the stress exceeds the endurance limit of the luting cement. Cementation with glass ionomer cement may help to reduce stress levels in SSC restorations of primary molars in children.

Efficacy of Three Interdental Cleaning Methods for Peri-Implant Health Maintenance of Single Implant-Supported Crowns: A Randomised Clinical Trial.

PURPOSE: To compare the effectiveness of an interproximal brush, a water flosser, and dental floss in removing plaque and reducing inflammation around implant-supported crowns. MATERIALS AND METHODS: A randomised controlled trial was conducted involving 45 participants with implant-supported single crowns. The participants were randomly assigned to three groups: interproximal brush, water flosser, and dental floss. Plaque index scores, gingival index scores, and interleukin-6 (IL-6) levels were assessed at baseline and after a two-week period. Statistical analysis was performed to compare the outcomes among the groups. RESULTS: Following the second visit, improvements in plaque control were observed across all three interdental cleaning methods. The water flosser demonstrated a slight reduction in IL-6 levels (60.17 ± 3.07 vs 58.79 ± 4.04) compared to the initial visit, although this decrease was not statistically significant. Conversely, both the interdental brush and dental floss exhibited a slight increase in IL-6 levels at the second visit (60.73 ± 2.93 and 55.7 ± 10.64, respectively) compared to the mean at the first visit (58.38 ± 3.24 and 54.6 ± 2.22, respectively). Among the groups, only the interproximal brush demonstrated a statistically significant difference in IL-6 levels (p=0.008), while no statistically significant differences were observed in the dental floss and water flosser groups. CONCLUSION: Within the study's limitations, our findings suggest that all three methods of interdental cleaning effectively improve plaque control and reduce gingival inflammation. However, using a water flosser appears to reduce inflammation more effectively, highlighting its potential advantage over the other two methods. Further research is needed to evaluate the long-term efficacy and impact of these methods on implant survival.

Risk factors associated with the survival of endodontically treated teeth: A retrospective chart review.

BACKGROUND: Studies on risk factors affecting tooth retention after endodontic treatment in dental school settings are limited. Understanding these factors is crucial for preserving teeth. The aim of this retrospective study was to evaluate patient- and tooth-level risk factors associated with the survival of endodontically treated teeth. METHODS: Electronic health records of patients who underwent endodontic treatment at the School of Dental Medicine at the University of Pennsylvania from 2017 through 2020 were analyzed. Patient-level factors included age, sex, American Society of Anesthesiologists Physical Status Classification, smoking history, diabetes status, and amoxicillin allergy. Tooth-level factors included position, presence of restorations, and periodontal conditions with preprosthetic treatments. RESULTS: The results of this study indicate that the patient-level factors significantly associated with tooth retention included age, sex, American Society of Anesthesiologists Physical Classification Status, and amoxicillin allergy. Tooth-level factors such as core buildup, full-coverage crown, healthy periodontium, and scaling and root planing were also associated with higher survival rates. Mandibular premolars had higher survival rates than mandibular molars. CONCLUSIONS: This investigation revealed that the tooth retention rate of endodontically treated teeth was 96.2% after initial root canal treatment, 92.4% for nonsurgical re-treatment, and 97.8% for surgical re-treatment. PRACTICAL IMPLICATIONS: The tooth retention of the endodontic treatment was associated with healthy periodontium, tooth structure, tooth position, tooth restoration, and the patient's overall health.

Single crowns in the posterior maxilla supported by either 11-mm long implants with sinus floor augmentation or by 6-mm long implants: A 10-year randomized controlled trial.

OBJECTIVES: To compare the clinical performance of single crowns in the posterior maxilla supported by either 11-mm long implants combined with maxillary sinus floor augmentation (MSFA) surgery or by 6-mm long implants during a 10-year follow-up period. MATERIALS AND METHODS: Subjects were randomly allocated to receive one 11-mm long implant in combination MFSA or to receive one 6-mm long implant without any grafting. Twenty-one implants in 20 patients were placed in the 6-mm group and 20 implants in 18 patients were placed in the 11-mm group. Both groups were followed by clinical and radiographic examinations up to 10 years. Patients' satisfaction was also scored before treatment. RESULTS: Two patients died and eight patients moved during the follow-up. Two patients lost an implant in the 6-mm group and one implant was lost in the 11-mm group (implant survival 89.5% and 90.9%, respectively). From loading to 10 years' follow-up, mean ± SE marginal bone loss in the 6-mm group and 11-mm group was 0.18 ± 0.10 mm and 0.26 ± 0.12 mm, respectively, without a significant difference between the groups at 10 years (p = .650). In both groups, indices scores for plaque, calculus, gingiva and bleeding were low as well as mean pocket probing depth. Patients' satisfaction at 10 years was high in both groups; mean overall satisfaction in the 6-mm group and 11-mm group was 9.6 ± 0.6 and 9.2 ± 0.8, respectively (p = .168). CONCLUSIONS: Placement of 6-mm implants or 11-mm implants combined MFSA are equally successful during a 10-year follow-up period when applied for supporting a single restoration.

Tooth morphology fusion technique is more accurate than conventional technique in transferring morphology of provisional to definitive screw-retained, implant-supported crown: A preliminary intervention study.

PURPOSE: To compare the accuracy of the tooth morphology fusion (TMF) digital technique and customized impression transfer coping (conventional) technique when transferring the morphology of a provisional crown to a definitive screw-retained implant-supported crown. METHODS: Six cases of partial edentulism (one anterior and five posterior) treated with oral implant placement in our clinic for the loss of three or fewer teeth in the maxilla or mandible between April 2017 and September 2018 were included. After implant placement and re-entry surgery, provisional restorations were made and adjusted to obtain the ideal morphology. Two definitive restorations were constructed by transferring the complete morphology of the provisional restorations, including the subgingival contour, using the TMF digital and conventional techniques. Three sets of surface morphological data were obtained using a desktop scanner. The three-dimensional total discrepancy volume (TDV) between the provisional restoration (reference) and the two definitive restorations was digitally measured by overlapping the surface data of the stone cast using the Boolean operation. Each TDV ratio (%) was calculated by dividing the TDV by the volume of provisional restoration. The median TDV ratios for TMF and conventional techniques were compared using the Wilcoxon signed-rank test. RESULTS: The median TDV ratio between provisional and definitive restorations constructed using the TMF digital technique (8.05%) was significantly lower than that obtained using the conventional technique (13.56%, P < 0.05). CONCLUSIONS: In this preliminary intervention study, the TMF digital technique was more accurate than the conventional technique for the transfer of morphology from provisional to definitive prosthesis.

The effect of aging on the accuracy of marginal adaptation and fracture resistance of CAD/CAM PEEK single crown restoration

Aim: In recent years, great advances have been made in the use of CAD/CAM to prepare fixed restorations. The marginal and internal fit of these restorations is a principal determinant for their clinical success. In addition, the nature of the oral environment affects the mechanical properties of these restorations. Therefore, this study aimed to investigate the effect of aging process under conditions that simulate the oral environment on the marginal adaptation, and, fracture resistance of crowns fabricated from polyether ether ketone (PEEK) using CAD/CAM methods. Methods: Twenty identical crown restorations were fabricated by using CAD/CAM methods to mill polyether ether ketone (PEEK) material. These crowns were produced by using a software design of an epoxy resin replica of the prepared maxillary first premolar tooth. All PEEK crowns were cemented and randomly divided into two equal groups (A, B). Each group was divided into subgroups (A1, A2 and B1, B2). Group A1 and A2 were used to measure marginal adaptation and fracture resistance, respectively, before aging, while group (B1 and B2) were measured after aging. The cemented crowns were mounted in resin molds to facilitate the sectioning process. The measurements of the marginal gap were performed after sectioning at four points using a stereomicroscope. The fracture resistance of the crowns was investigated using a universal testing machine. A statistical analysis was performed using the GraphPad Prism® software version and unpaired Student's t-test. Results: The results revealed that aging affected the marginal gap, and the fracture resistance of the PEEK crowns. While aging, negatively affected the conditions under investigation, however the least significant difference of marginal gap was found in the margin region. Conclusions: PEEK-CAD/CAM is considered as a good alternative prosthodontic material for fixed prostheses. The CAD/CAM technique used to make PEEK crown restorations in our study offers the advantages of high marginal accuracy and fracture resistance for long-term performance in the oral environment

Comparison of Fracture Resistance between Different Treatment Modalities of Mutilated Endodontically Treated Teeth Using Polyether Ether Ketone.

AIM: To compare fracture resistance of multiple treatment modalities intended for mutilated teeth using polyether ether ketone (PEEK) and zirconia materials. MATERIALS AND METHODS: The study was divided into four groups according to treatment modality adopted (n = 14): fiber post (F), Nayyar core (N), endocrown (E), and Richmond crown (R). Each group was further subdivided into two groups (n = 7) according to the type of material used: zirconia (Z) and PEEK (P). Using computer-aided design/computer-aided manufacturing, restorations were constructed from both materials following tested treatment options and manufacturer direction. Finished restorations were then tried, seated, and cemented to their corresponding acrylic teeth. All specimens were tested for fracture resistance in universal testing machine with cross head speed of 0.5 mm/min speed until failure, which was confirmed by a sudden drop in the measurements of the testing machine. Results were recorded, tabulated, and statistically analyzed. Shapiro-Wilk normality tests were considered to evaluate the normality of the data distributions. One-way analysis of variance (ANOVA) followed by Tukey's post hoc analysis was conducted to analyze the fracture resistance significant differences. RESULTS: Descriptive statistics of the restoration material revealed statistically a higher mean value for PEEK material (3609 ± 188.1) than zirconia (2404 ± 425.6). One-way ANOVA revealed statistically significant differences between zirconia group (p < 0.0001). Regarding zirconia group statistical significance was detected between fiber post vs endocrown (p = 0.0299), fiber post vs Richmond crown (p < 0.0001), and Nayyar core vs Richmond crown (p = 0.0004). However, there was no statistically significant difference between PEEK group (P = 0.1614). CONCLUSION: Polyether ether ketone could present a reliable treatment option in endodontically treated teeth. CLINICAL SIGNIFICANCE: Using one-piece Richmond crowns constructed of PEEK could present a viable treatment option against conventional treatment options of root canal treatment (RCT) single-rooted teeth.

Effect of Novel Low-intensity Pulsed Ultrasound Stimulation on Accelerated Implant Osteointegration in Canine.

AIM: To evaluate the effect of low-intensity pulsed ultrasound (LIPU) application on dental implant accelerated osseointegration in the two-stage implant protocol. MATERIALS AND METHODS: A total of 20 implants were placed in 10 mature mongrel dogs, two implants for each dog replacing the lower 3rd premolars bilaterally. After 3 months of extraction, implants were placed. After 24 hours of implantation, the right sides received LIPU for 20 mins/day, continuously for 20 days. The left sides didn't receive LIPU (control). Standardized radiographs were taken before LIPU and after 10 and 20 days for both sides. After 20 days of LIPU application, second-stage surgery was performed and provisional crowns were placed on each implant. Implants were subjected to functional occlusal loading for 4 weeks. Standardized radiographs were taken after 2 and 4 weeks of loading and analyzed to assess the peri-implant bone density changes. All data were collected, tabulated, and statistically analyzed. RESULTS: All tissues appeared clinically normal, with the absence of inflammation and peri-implant radiolucency. The survival rate was 100%. The LIPU group showed a statistically significantly higher percentage increase in mean bone density after 10 LIPU sessions, 20 LIPU sessions, and 2 and 4 weeks of loading, than a control group. CONCLUSION: The LIPU stimulation radiographically increased the bone density around implant area and accelerated osseointegration in the two-stage implant protocol. CLINICAL SIGNIFICANCE: Low-intensity pulsed ultrasound stimulation could be beneficial in accelerating osseointegration and thus shortening the waiting period for final prosthetic delivery.

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

BACKGROUND: The 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). METHODS: Forty-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. RESULTS: A 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. CONCLUSIONS: Both 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 NUMBER: NCT05049694.

The challenge of ceramic restorations on dark substrate: a case report.

The use of dental ceramics on anterior teeth is associated with predictable and long-lasting esthetic results. However, treatment on darkened substrates is challenging. Various conservative options, including ceramic veneers, are available to change the shape and color of anterior teeth. The aim of this case report is to describe the esthetic rehabilitation of a darkened central incisor in a maxillary anterior region that had irregular gingival contours, multiple composite resin restorations, and unsatisfactory tooth shapes. Harmony was restored through periodontal recontouring surgery, placement of a lithium disilicate crown (consisting of a veneer cemented to a coping) on the darkened central incisor, and placement of lithium disilicate veneers on the other maxillary anterior teeth.

Bone Volume Assessment Around Immediate Dental Implant in the Esthetic Area with Immediate Tooth-Like Single Crown Provisionalization: A Laser and Computed Tomography 1-Year Retrospective Study.

PURPOSE: To examine the remodeling process of both the soft and hard tissue components of the postextraction socket around immediately loaded dental implants after tooth extraction in maxillary esthetic areas. MATERIALS AND METHODS: Subjects underwent immediate placement of single implants in postextraction sockets without bone grafting, and their immediate provisionalization with custom tooth-like interim crowns were fabricated using digital diagnostic impressions and a dental milling machine. Intraoperative and 1-year follow-up layered scans of the postextraction sockets after implantation were acquired using a 3D optical system. In the short term, subjects underwent computed tomographic scans. Digital impressions for gingival contours, originally stored as STL (standard tessellation language) files, were converted to DICOM (Digital Imaging and Communications in Medicine) files with the implant shoulder working as a referral point, which were then superimposed to 3D radiologic images. The observed volumetric and linear outcomes were measured using a program known as DentaScan. The width of the alveolar crest at the level of the implant shoulder and marginal bone levels were acquired. Nonparametric tests were applied with a level of significance set at P < .01. RESULTS: No failure was reported after a follow-up of 1 year. Little or no inflammation of the treated areas was registered, and there were practically no signs of suppuration. The areas showed a significant reduction in the overall volumes for both soft and bone tissue, with a P value < .0001 from the baseline (0.983 ± 0.172 cm3) to the 1-year survey (0.865 ± 0.156 cm3). If the soft and bone tissue changes were separately evaluated, a significant loss (with a P value < .0001) was registered for only the bone tissues (from 0.434 ± 0.075 to 0.355 ± 0.061 cm3). Moreover, changes in gingival tissue from baseline to the 1-year survey (-0.040 ± 0.067) appeared to be significantly different from the overall volume loss (-0.118 ± 0.083 cm3). A shrinkage in width (-0.5 ± 0.7 mm) was found from baseline (12.6 ± 0.6 mm) to the 1-year follow-up (12.1 ± 0.9 mm). Marginal bone levels were 0.97 ± 0.70 mm and 0.39 ± 0.78 mm, respectively, at the mesial and distal aspects of the implants. CONCLUSIONS: The present analysis suggested that immediately customized provisionalization was effective enough to prevent both volume loss and linear shrinkage at the layers of the treated areas. Moreover, the buccal aspects seemed to be the areas most affected by the loss of volume. The mean loss in width, which amounted to roughly 0.5 mm, appeared to be negligible when compared to the overall width measured before surgery.

The in-vitro accuracy of fiducial marker-based versus markerless registration of an intraoral scan with a cone-beam computed tomography scan in the presence of restoration artifact.

OBJECTIVES: To determine the effect of restoration artifact ('metal artifact') on registration accuracy of an intraoral scan and cone-beam computed tomography (CBCT) scan, comparing fiducial marker-based registration with markerless registration. MATERIALS AND METHODS: A maxillary model was fitted with multiple configurations of zirconia crowns to simulate various states of oral rehabilitation. Intraoral scans and CBCT scans (half and full rotation) were acquired. Registration was performed using markerless (point-based registration with surface-based refinement) and fiducial marker-based registration. Each experimental condition was repeated 10 times (n = 320). The absolute deviation was measured at the canines and first molars, and the average and maximum values were analysed using multiple linear regression. RESULTS: R2 was 0.874 for average error and 0.858 for maximum error. For markerless registration, there were 0.041 mm (p < .001) and 0.045 mm (p < .001) increases in average and maximum error per crown, respectively. For fiducial marker-based registration, the effect of additional crowns was not statistically significant for average (p = .067) or maximum (p = .438) error. For a full arch of crowns, the regression model predicted average and maximum errors of 0.581 and 0.697 mm for the markerless technique, and 0.185 and 0.210 mm for the fiducial marker-based technique. Overall, the fiducial marker-based technique was more accurate for four or more crowns. The half rotation scan increased average error by 0.021 mm (p = .001) and maximum error by 0.029 mm (p < .001). CONCLUSIONS: Under the present study's experimental conditions, the fiducial marker-based technique should be considered if four or more full-coverage highly radiopaque restorations are present.

Bite force evaluation at maximal intercuspal position: An in vivo comparative study between stainless steel and zirconia crowns on primary molar teeth.

Objective: The objective of this study was to clinically evaluate and compare the mean bite force changes at maximum intercuspal position, along with parental satisfaction following full crown restoration using stainless steel crown/zirconia crown on primary molar teeth using digital occlusal analysis system T-Scan III (Tekscan Corp, Boston, Mass., USA). Materials and Methods: Thirty-six primary molars of children aged 6-9 years with pulpal involvement were selected for the study. The selected teeth were allocated to either of the two groups using simple random sampling technique: Group A = stainless steel crowned teeth and Group B = zirconia crowned teeth. The mean bite force was recorded before the placement of the crown, after the placement of the crown, and after 1 month-follow-up. The inter-group and intra-group comparison was done among the groups. After the placement of the crown, parents were asked to fill out a questionnaire for assessing parental satisfaction. Results: A significant result in the bite force on crowned tooth, vertical dimension was seen from baseline to 1-month follow-up between the SSC and zirconia groups. In the zirconia crown group, the mean bite force was more compared to the stainless steel crown group. Parents' satisfaction was higher with zirconia crown in terms of color and esthetics. Conclusion: SSC is more acceptable than zirconia crown since occlusal re-equilibration was attained better in SSC as compared to zirconia crown.

A double-blind randomized within-subject study to evaluate clinical applicability of four digital workflows for the fabrication of posterior single implant crown.

OBJECTIVE: To compare efficiency and clinical efficacy of posterior single implant crowns (PSIC) fabricated using four digital workflows. MATERIALS AND METHODS: Twenty-two patients with one missing first molar were included. Each patient received four screw-retained implant crowns fabricated through four different workflows including a fully digital workflow with immediate digital impression (Group i-IOS), a fully digital workflow with digital impression after implant osseointegration (Group d-IOS), a model-based hybrid workflow using immediate analogue impression (Group i-AI), and a model-based hybrid workflow with conventional analogue impression after implant osseointegration (Group d-AI). The crown delivery sequence was randomized and blinded. The efficiency for each workflow and clinical outcome of each crown were recorded. RESULTS: The average clinical working time in fully digital workflows (i-IOS 46.90 min, d-IOS 45.66 min) was significantly lower than that in the hybrid workflows (i-AI 54.59 min, d-AI 55.96 min; p < .001). Significantly more laboratory time was spent in hybrid workflows (i-AI 839.60 min, d-AI 811.73 min) as compared to fully digital workflows (i-IOS 606.25 min, d-IOS 607.83 min, p < .01). No significant differences in the chairside time at delivery were found. More crowns in Group i-AI (15%) needed additional laboratory interventions than in the other groups (p = .029). CONCLUSION: Digital impression and model-free fully digital workflow improved prosthetic efficiency in the fabrication of PSIC. With the limitation that the results were only applicable to the implant system used and the digital technologies applied, findings suggested that workflows integrating immediate impression with implant surgery procedure was clinically applicable for restoration of PSIC.