Auto-Segmentation and Quantification of Non-Cavitated Enamel Caries Imaged with Swept-Source Optical Coherence Tomography.

(1) Background: OCT imaging has been used to assess enamel demineralization in dental research, but it is not yet developed enough to qualify as a diagnostic technique in clinics. The current capabilities of most commercial acquisition software allow for visual and qualitative assessments. There is a need for a fast and verified batch-processing algorithm to segment and analyze demineralized enamel. This study suggests a GUI MATLAB algorithm for the processing and quantitative analysis of demineralized enamel. (2) Methods: A group of artificially demineralized human enamels was in vitro scanned under the OCT, and ROI frames were extracted. By using a selected intensity threshold colormap, Inter- (Ie) and Intra- (Ia) prismatic demineralization can be segmented. A set of quantitative measurements for the average demineralized depth, average line profile, and integrated reflectivity can be obtained for an accurate assessment. Real and simulated OCT frames were used for algorithm verification. (3) Results: A strong correlation between the automated and known Excel measurements for the average demineralization depth was found (R2 > 0.97). (4) Conclusions: OCT image segmentation and quantification of the enamel demineralization zones are possible. The algorithm can assess the future development of a real-time assessment of dental diagnostics using an oral probe OCT.

Resident selection, assessment, and management: Proceedings of the 2022 ADEA Advanced Dental Education Summit.

The fifth biennial Advanced Dental Education Summit was organized by the ADEA Council on Advanced Education Programs. With a focus on "Resident selection, assessment, and management," the summit aimed to discuss best practices for selecting, assessing, and managing advanced education residents. Expert presentations covered the resident's journey from interview to graduation, emphasizing strategies for supporting resident wellness, success, and evaluation. The summit provided recommendations, including the incorporation of psychosocial assessments in the selection process, early recognition of behavioral issues, clearly defining clinical competencies, and creating a culture of wellness through supportive policies and structures.

Dental Utilization in a Pediatric Emergency Department and Urgent Care Centers Before, During, and After Shutdown of a Pediatric Dental Clinic During the COVID-19 Pandemic, 2019-2021.

OBJECTIVES: Limited data are available on how the closure of pediatric dental clinics because of the COVID-19 pandemic affected hospital pediatric emergency department (ED) visits in the United States. We evaluated changes in dental-related visits at a pediatric ED and associated urgent care centers (UCCs) after the shutdown of a large pediatric dental clinic because of the COVID-19 pandemic. METHODS: We conducted a single-center retrospective medical record review of 811 patients aged 0 to 17 years who presented to a pediatric ED or associated UCC at Rady Children's Hospital-San Diego for dental-related concerns from March 19, 2019, through January 17, 2021. Patients were classified into 3 periods: before shutdown, during shutdown, and after shutdown. We collected data on demographic characteristics; International Classification of Diseases, Tenth Revision codes; dental diagnosis; treatment; and COVID-19 test results. We compared the frequency and proportion of patients seen for dental-related concerns, dental diagnosis, and treatment during the 3 periods. RESULTS: The proportion of dental-related concerns in the ED doubled during the shutdown (0.7%) and was 1.5 times higher after the shutdown (0.6%) compared with before the shutdown (0.4%; P < .001). Significantly more patients were seen in EDs than in UCCs during and after the shutdown than before the shutdown (P = .005). During and after the shutdown, admission to the hospital for antibiotic treatment increased significantly to 6.5% and 7.9%, respectively, compared with before the shutdown (2.8%; P = .022), and nonaerosolized procedures and ED/UCC discharge increased to 13.4% and 9.3%, respectively, compared with before the shutdown (6.2%; P = .015). CONCLUSIONS: Mitigating future closures of dental offices is important given the shifted burden of dental care to the ED.

Displacement of a Dental Implant into the Pterygoid Fossa: A Clinical Report.

The placement of dental implants in the pterygomaxillary region can be advantageous in maxillary complete arch fixed implant-supported prosthetic rehabilitations to avoid bone grafting and sinus elevation surgeries. Pterygomaxillary implants improve implant biomechanics by eliminating distal cantilevers and increasing the anteroposterior spread with reported mean implant survival rates comparable to traditional implant sites. Although only minor surgical complications have been reported in the literature with the placement of dental implants in the pterygomaxillary region this clinical report describes a major surgical complication involving the displacement of a dental implant into the pterygoid fossa.

Clinical and microbiologic investigation of an expedited peri-implantitis dog model: an animal study.

BACKGROUND: Animal studies are pivotal in allowing experimentation to identify efficacious treatment protocols for resolution of peri-implantitis. The purpose of this investigation was to characterize an expedited dog peri-implantitis model clinically, radiographically, and microbiologically. METHODS: Eight hound dogs underwent extractions (week 0) and implant (3.3 × 8.5 mm) placement with simultaneous surgical defect creation and ligature placement for induction of peri-implantitis (week 10). Ligatures were replaced at 6 weeks (week 16) and removed after 9 weeks (week 19) when supporting bone loss involved approximately 50% of the peri-implant bone. Microbial samples from the defects and healthy control implant sites collected at week 19 were analyzed utilizing a microarray. Clinical measures of inflammation were obtained and radiographic bone loss was measured from periapical radiographs. Radiographic depth and width measurements of bony defect were repeated at weeks 10 (baseline), 16, and 19. Canonical analysis of principal coordinates was used to visualize overall differences in microbial abundance between peri-implantitis and healthy implants. RESULTS: This accelerated disease protocol led to intrabony defect creation with a mean depth and width of 4.3 mm and 3.5 mm, respectively after 9 weeks of ligature placement. Microbial identification revealed 59 total bacteria in peri-implant sites, 21 of which were only present in peri-implant sites as compared to healthy controls. Overall microbial beta diversity (microbial between-sample compositional diversity) differed between peri-implantitis and healthy implants (p = 0.009). CONCLUSIONS: Within the limitations of this study, this protocol led to expedited generation of peri-implant defects with a microbial profile indicative of a shift to disease and defect patterns conducive to regenerative treatment. However, the possibility of potential spontaneous resolution of lesions due to the lack of a chronicity interval as compared to chronic disease models need to be further clarified and considered during preclinical peri-implantitis model selection.

A Specialized Pediatric Emergency Medicine Track Decreases Computed Tomography in Head Injured Patients.

BACKGROUND: There is an increased emphasis on reducing exposure to ionizing radiation in pediatric patients. Guidelines from the Pediatric Emergency Care Applied Research Network help practitioners identify patients at low risk for clinically important traumatic brain injury after head injury. OBJECTIVES: We seek to determine whether the institution of a pediatric track staffed by pediatric emergency medicine physicians (PEMs) within a community emergency department (ED) impacts the overall utilization of head computed tomography (CT) on children younger than 15 years with head injury. METHODS: We used a retrospective cohort analysis of patients under the age of 15 years presenting to a community ED in the year before and the year of institution of a pediatric emergency track. Relative risk estimates were used to determine the risk of CT use associated with nonpediatric-trained emergency providers. RESULTS: The community ED saw 11,094 patients and 14,639 patients younger than 15 years in fiscal years 2014-2015 and 2015-2016, respectively. In the year before PEMs, there were 312 children younger than 15 years seen for head injury; 47.09% received head CTs. After PEM coverage, there were 396 children younger than 15 years seen for head injury; 17.17% received head CTs. Pediatric patients with head injury were 2.2 times more likely to receive CTs before the institution of the pediatric track (95% confidence interval, 1.8-2.6). CONCLUSION: The implementation of a pediatric emergency track demonstrated a significant decrease in CT utilization for head injury. Continued development of pediatric tracks in community EDs can lead to reduction of CTs.

The Impact of Behavioral Health Patients on a Pediatric Emergency Department's Length of Stay and Left Without Being Seen.

OBJECTIVE: Emergency department (ED) boarding of admitted patients negatively impacts ED length of stay (LOS). Behavioral health (BH) patients are often challenging to safely discharge. We examined the association between daily BH census and non-BH LOS and left without being seen (LWBS) rates. METHODS: Retrospective analysis of BH and non-BH patients at a high-volume tertiary care pediatric ED from December 2014 to June 2016 examined the association between BH patients and non-BH LOS and LWBS rates. Behavioral health patients were identified by presence of social work assessment and BH chief complaint and/or final diagnosis. Data were analyzed using 1-sample test of proportions, Student t test, Spearman and Pearson correlations, logistic regression, and odds ratios with 95% confidence intervals. RESULTS: A total of 143,141 patients were seen, 3% (n = 4351) for BH presentations. Median LOS for discharged non-BH patients was 128 minutes compared with 446 minutes for BH patients. Daily LOS and bed hold hours were significantly longer for BH than for non-BH patients (P < 0.0001 for each analysis). After adjusting for ED census, daily BH census was significantly associated with increasing LWBS rates and non-BH LOS. CONCLUSIONS: Behavioral health census and bed hold hours were significantly associated with increased LOS and LWBS rates and with our inability to meet desired LOS and LWBS rates. These associations support the existence of a threshold where the ED has reached capacity and is no longer able to absorb BH patients. Improving BH facility access may help improve overall pediatric ED patient care.

Postmortem evaluation of mandibular implant-supported fixed complete denture after 30 years of service.

A postmortem evaluation of a 5-implant-supported mandibular fixed complete denture that had successfully opposed a maxillary conventional complete denture for 30 years was undertaken. Before embalming, radiographs, implant stability measurements, push-in failure load tests, and histomorphometric analyses were performed on the implants and the mandible. Evaluation of this cadaver suggests that an edentulous mandible restored with an implant-supported fixed prosthesis can function successfully for over 30 years with few complications.

Comparison of the correlation of photoelasticity and digital imaging to characterize the load transfer of implant-supported restorations.

STATEMENT OF PROBLEM: Whether splinting or not splinting adjacent implants together can optimize the stress/strain transfer to the supporting structures remains controversial. PURPOSE: The purpose of this study was to compare the photoelasticity and digital image correlation (DIC) in analyzing the stresses/strains transferred by an implant-supported prosthesis. MATERIAL AND METHODS: A polymethylmethacrylate model was made with a combination of acrylic resin replicas of a mandibular first premolar and second molar and threaded implants replacing the second premolar and first molar. Splinted (G1/G3) and nonsplinted (G2/G4) metal-ceramic screw-retained crowns were loaded with (G1/G2) and without (G3/G4) the presence of the second molar. Vertical static loads were applied to the first molar implant-supported crown (50 N-photoelasticity; 250 N-DIC). The resulting isochromatic fringes in the photoelastic models were photographed, and a single-camera 2-dimensional DIC system recorded the deformation at the surface of the resin models. RESULTS: Residual stresses were present in the photoelastic model after screw fixation of the crowns. The following average photoelastic stress results (MPa) were found around the loaded implant: G1 (20.06), G2 (23.49), G3 (30.86), G4 (37.64). Horizontal strains (εxx, %) between the molars averaged over the length of the loaded implant were found by DIC: G1 (0.08 ± 0.09), G2 (0.13 ± 0.10), G3 (0.13 ± 0.11), G4 (0.16 ± 0.11). Splinted crowns transferred lower stresses to the supporting bone when the second molar was absent. The second molar optimized the stress distribution between the supporting structures even for nonsplinted restorations. CONCLUSIONS: Both methods presented similar results and seemed capable of indicating where issues associated with stress/strain concentrations might arise. However, DIC, while apparently less sensitive than photoelasticity, is not restricted to the use of light-polarizing materials.

Validation of finite element models for strain analysis of implant-supported prostheses using digital image correlation.

OBJECTIVES: A validated numerical model for stress/strain predictions is essential in understanding the biomechanical behavior of implant-supported dental prostheses. The digital image correlation (DIC) method for full-field strain measurement was compared with finite element analysis (FEA) in assessing bone strain induced by implants. METHODS: An epoxy resin model simulating the lower arch was made for the experimental test with acrylic resin replicas of the first premolar and second molar and threaded implants replacing the second premolar and first molar. Splinted (G1/G3) and non-splinted (G2/G4) metal-ceramic screw-retained crowns were fabricated and loaded with (G1/G2) or without (G3/G4) the second molar that provided proximal contact. A single-camera, two-dimensional DIC system was used to record deformation of the resin model surface under a load of 250N. Three-dimensional finite element (FE) models were constructed for the physical models using computer-aided design (CAD) software. Surface strains were used for comparison between the two methods, while internal strains at the implant/resin block interface were calculated using FEA. RESULTS: Both methods found similar strain distributions over the simulant bone block surface, which indicated possible benefits of having splinted crowns and proximal contact in reducing bone strains. Internal strains predicted by FEA at the implant-resin interface were 8 times higher than those on the surface of the model, and they confirmed the results deduced from the surface strains. FEA gave higher strain values than experiments, probably due to incorrect material properties being used. SIGNIFICANCE: DIC is a useful tool for validating FE models used for the biomechanical analysis of dental prosthesis.

Comparison of push-in versus pull-out tests on bone-implant interfaces of rabbit tibia dental implant healing model.

PURPOSE: This study aimed to investigate whether push-in and pull-out tests measure mechanical properties of the bone-implant interface differently, and which test is more sensitive to changes over the healing period. MATERIALS AND METHODS: Two identical self-threading dental implants (3.3×8.5mm) were placed in medial surface of the proximal condyles of left and right tibias of 20 rabbits (40 implants total). Five rabbits each were sacrificed after 1, 4, 8, and 12 weeks of healing. Push-in test was performed on one side's tibia implant and pull-out on the other side's implant, at a rate of 6mm/min. Primary and secondary implant stabilities and tibia weight were measured on all implants. RESULTS: The push-in test generated significantly higher failure load (p=.0001; 530N vs 279N), lower displacement at failure (p=.0003; 0.436mm vs 0.680mm), and higher interface stiffness (p<.0001; 1,641N/mm vs 619N/mm) than pull-out test. Failure load, stiffness, and secondary implant stability were significantly higher for longer compared with shorter healing periods, while displacement, tibia weight, and primary stability were not. Failure load and stiffness differed significantly for four healing times for the push-in but not for the pull-out test. Failure load was significantly correlated with secondary implant stability for both push-in (r=0.66) and pull-out (r=0.48) tests, but stiffness was significantly correlated with secondary stability only for the push-in test (r=0.72; pull-out test r=0.40). CONCLUSION: The push-in test appeared more sensitive than pull-out to changes in mechanical properties at bone-implant interfaces during healing in rabbit tibia model.

Prevalence of sinus augmentation associated with maxillary posterior implants.

Pneumatization of the maxillary sinus limits the quantity of alveolar bone available for implant placement and may result in a lack of primary stability and difficulty in achieving osseointegration. The purpose of this study was to retrospectively analyze a group of patients who had implants placed in the posterior maxilla, calculate the prevalence of sinus augmentation, and identify factors related to sinus augmentation. With institutional review board approval, dental records from a population of patients who had implants placed in the maxillary posterior region between January 2000 and December 2004 were used to create a database. Independent variables were classified as continuous (age of the patient at stage 1 implant surgery [S1], time between extraction and S1, time between extraction and sinus augmentation, and time between sinus augmentation and S1) and categorical (gender, implant failure, American Society of Anesthesiologists system classification, smoking, osteoporosis, residual crestal bone height, implant position, implant proximity, prostheses type, and implant diameter and length). The dependent variable was the incidence of a sinus augmentation procedure. Simple logistic regression was used to assess the influence of each factor on the presence of sinus augmentation (P < .05). The final database included 502 maxillary posterior implants with an overall survival rate of 93.2% over a mean follow-up period of 35.7 months. Of 502 implants, 272 (54.2%) were associated with a sinus augmentation procedure. Among variables, residual crestal bone height (P < .001), implant position (P < .001), implant proximity (P < .001), prosthesis type (P < .001), implant failure (P < .01), and implant diameter (P < .01), were statistically associated with sinus augmentation. Within the limitations of this retrospective study, the results suggest that more than half (54.2%) of the maxillary posterior implants were involved with a sinus augmentation procedure. The prevalence of sinus augmentation increased with decreased residual crestal bone height, more posterior implant locations, and complete or partial edentulism. Sinus augmentation was significantly associated with implant failure and wide implants.

Effect of surgical guide design and surgeon's experience on the accuracy of implant placement.

Implant position is a key determinant of esthetic and functional success. Achieving the goal of ideal implant position may be affected by case selection, prosthodontically driven treatment planning, site preparation, surgeon's experience and use of a surgical guide. The combined effect of surgical guide design, surgeon's experience, and size of the edentulous area on the accuracy of implant placement was evaluated in a simulated clinical setting. Twenty-one volunteers were recruited to participate in the study. They were divided evenly into 3 groups (novice, intermediate, and experienced). Each surgeon placed implants in single and double sites using 4 different surgical guide designs (no guide, tube, channel, and guided) and written instructions describing the ideal implant positions. A definitive typodont was constructed that had 3 implants in prosthetically determined ideal positions of single and double sites. The position and angulation of implants placed by the surgeons in the duplicate typodonts was measured using a computerized coordinate measuring machine and compared to the definitive typodont. The mean absolute positional error for all guides was 0.273, 0.340, 0.197 mm in mesial-distal, buccal-lingual, vertical positions, respectively, with an overall range of 0.00 to 1.81 mm. The mean absolute angle error for all guides was 1.61° and 2.39° in the mesial-distal and buccal-lingual angulations, respectively, with an overall range of 0.01° to 9.7°. Surgical guide design had a statistically significant effect on the accuracy of implant placement regardless of the surgeon's experience level. Experienced surgeons had significantly less error in buccal-lingual angulation. The size of the edentulous sites was found to affect both implant angle and position significantly. The magnitude of error in position and angulation caused by surgical guide design, surgeon's experience, and site size reported in this study are possibly not large enough to be clinically significant; however, it is likely that errors would be magnified in clinical practice. Future research is recommended to evaluate the effect of surgical guide design in vivo on implant angulation and position error.

Digital image correlation analysis on the influence of crown material in implant-supported prostheses on bone strain distribution.

PURPOSE: A digital image correlation (DIC) method for full-field surface strain measurement was used to analyze the effect of two veneering materials for implant supported crowns on the strain distribution within the surrounding bone. METHODS: An epoxy resin model of a bone block was made by housing acrylic resin replicas of a mandibular first premolar and second molar together with threaded implants replacing the second premolar and first molar. Porcelain-veneered (G1 and G3) and resin-veneered (G2 and G4) screw-retained splinted crowns were fabricated and loaded with (G1 and G2) and without (G3 and G4) the presence of the second molar replica. A 2-dimensional DIC measuring system was used to record surface deformation of the bone block model at a frequency of 1.0 Hz during application of a 250-N load. RESULTS: Maximum compressive strains (ɛ(XX), %) were found for the following regions: between molars, G1 (-0.21), G2 (-0.18), G3 (-0.26), and G4 (-0.25); between implants, G1 (-0.19), G2 (-0.13), G3 (-0.19), and G4 (-0.14). The magnitude of strains in the simulated bone block with the resin-veneered crowns was lower than that with porcelain-veneered crowns, irrespective of the presence or absence of the second molar. CONCLUSIONS: The softer resin veneer helped to spread the load more evenly amongst the supporting teeth and implants, thus reducing the strains in the simulant bone block. Conversely, using the harder porcelain veneer resulted in the load being concentrated within one or two teeth or implants, thus leading to higher strain values in the bone block.

Dental students choosing licensure path give more consideration to career flexibility rather than ethical dilemmas.

Although a patient-based clinical licensure examination (CLE) has been used in the United States for many decades to evaluate an individual's competency to practice dentistry, there continue to be validity, reliability, and ethical issues of concern to the profession. As a result of a 2009 decision by the Minnesota Board of Dentistry, dental students from the University of Minnesota School of Dentistry, beginning with the Class of 2010, are eligible for initial licensure in Minnesota by passing the nonpatient-based National Dental Examining Board of Canada Examination. Surveys were distributed to 101 senior dental students to assess what factors students used to decide whether or not to register for a patient-based CLE. The response rate to the survey was 84.2% (85/101). The opportunity to apply for a license in multiple states after passing a patient-based CLE was the primary factor in influencing the students to register for a patient-based CLE. Regarding the use of live patients in a CLE, students were most concerned with having to operatively restore teeth that could be treated more conservatively and for other reasons outside of their control, such as the patient failing to show up, patient not being accepted by the examiners, and procedural issues during the examination.

Digital image correlation analysis of the load transfer by implant-supported restorations.

This study compared splinted and non-splinted implant-supported prosthesis with and without a distal proximal contact using a digital image correlation method. An epoxy resin model was made with acrylic resin replicas of a mandibular first premolar and second molar and with threaded implants replacing the second premolar and first molar. Splinted and non-splinted metal-ceramic screw-retained crowns were fabricated and loaded with and without the presence of the second molar. A single-camera measuring system was used to record the in-plane deformation on the model surface at a frequency of 1.0Hz under a load from 0 to 250N. The images were then analyzed with specialist software to determine the direct (horizontal) and shear strains along the model. Not splinting the crowns resulted in higher stress transfer to the supporting implants when the second molar replica was absent. The presence of a second molar and an effective interproximal contact contributed to lower stress transfer to the supporting structures even for non-splinted restorations. Shear strains were higher in the region between the molars when the second molar was absent, regardless of splinting. The opposite was found for the region between the implants, which had higher shear strain values when the second molar was present. When an effective distal contact is absent, non-splinted implant-supported restorations introduce higher direct strains to the supporting structures under loading. Shear strains appear to be dependent also on the region within the model, with different regions showing different trends in strain changes in the absence of an effective distal contact.