The precision of drill calibration for dynamic navigation.

OBJECTIVES: To quantify the reproducibility of the drill calibration process in dynamic navigation guided placement of dental implants and to identify the human factors that could affect the precision of this process in order to improve the overall implant placement accuracy. METHODS: A set of six drills and four implants were calibrated by three operators following the standard calibration process of NaviDent® (ClaroNav Inc.). The reproducibility of the position of each tip of a drill or implant was calculated in relation to the pre-planned implants' entry and apex positions. Intra- and inter-operator reliabilities were reported. The effects of the drill length and shape on the reproducibility of the calibration process were also investigated. The outcome measures for reproducibility were expressed in terms of variability range, average and maximum deviations from the mean distance. RESULTS: A satisfactory inter-rater reproducibility was noted. The precision of the calibration of the tip position in terms of variability range was between 0.3 and 3.7 mm. We noted a tendency towards a higher precision of the calibration process with longer drills. More calibration errors were observed when calibrating long zygomatic implants with non-locking adapters than with pointed drills. Flexible long-pointed drills had low calibration precision that was comparable to the non-flexible short-pointed drills. CONCLUSION: The clinicians should be aware of the calibration error associated with the dynamic navigation placement of dental and zygomatic implants. This should be taken in consideration especially for long implants, short drills, and long drills that have some degree of flexibility. CLINICAL SIGNIFICANCE: Dynamic navigation procedures are associated with an inherent drill calibration error. The manual stability during the calibration process is crucial in minimising this error. In addition, the clinician must never ignore the prescribed accuracy checking procedures after each calibration process.

The Accuracy of Intraoral Registration for Dynamic Surgical Navigation in the Edentulous Maxilla.

PURPOSE: Despite the high clinical accuracy of dynamic navigation, inherent sources of error exist. The purpose of this study was to improve the accuracy of dynamic-navigated surgical procedures in the edentulous maxilla by identifying the optimal configuration of intraoral points that results in the lowest possible registration error for direct clinical implementation. MATERIALS AND METHODS: Six different four-area configurations (left and right sides; n = 12) were tested by three operators against two negative controls (left and right sides) and one positive control (three-area and eight-area configurations, respectively) using a skull model. The two dynamic navigation systems (X-Guide and Navident) and the two registration methods (bone surface tracing and fiducial markers) produced four registration groups: XG tracing, ND tracing, XG fiducial, and ND fiducial. The accuracy of the registration was checked at the frontal process of the zygoma. Intra- and interoperator reliabilities were reported for each registration group. Multiple comparisons were conducted to find the best configuration with the minimum registration error. RESULTS: Ranking revealed one configuration in the tracing groups (Conf.3) and two configurations in the fiducial groups (Conf.3 and Conf.5) that had the best accuracy. When the inferior surfaces of the zygomatic buttress were excluded, fiducial registration produced better accuracy with both systems (P = .006 and < .0001). However, bilaterally tracing 1-cm areas at these surfaces resulted in similar registration accuracy to placing fiducial markers there (P = .430 and .237). Navident performed generally better (P = .049, .001, and .002), but the values had a wider margin of uncertainty. Changing the distribution of the four tracing areas or fiducial markers had a less pronounced effect with the X-Guide than with the Navident system. CONCLUSIONS: For surgery in the edentulous maxilla, four fiducial markers placed according to Conf.3 or Conf.5 resulted in the lowest registration error. Where implants are being placed bilaterally, an additional two sites may further reduce the error. For bilateral zygomatic implant placement, it is optimal to place two fiducial markers on the inferior surfaces of the maxillary tuberosities, two on their buccal surfaces, and another two on the anterior labial surface of the alveolar bone. Utilizing the inferior zygomatic buttress is recommended over the inferior maxillary tuberosities in other types of maxillary surgeries.

Longitudinal assessment of undergraduate dental students: Building evidence for validity.

PURPOSE: To investigate the content and criterion validity, and reliability of longitudinal clinical assessment of undergraduate dental student clinical competence by determining patterns of clinical performance and comparing them with validated standalone undergraduate examinations. METHODS: Group-based trajectory models tracking students' clinical performance over time were produced from LIFTUPP© data for three dental student cohorts (2017-19; n = 235) using threshold models based on the Bayesian information criterion. Content validity was investigated using LIFTUPP© performance indicator 4 as the threshold for competence. Criterion validity was investigated using performance indicator 5 to create distinct trajectories of performance before linking and cross-tabulating trajectory group memberships with a 'top 20%' performance in the final Bachelor of Dental Surgery (BDS) examinations. Reliability was calculated using Cronbach's alpha. RESULTS: Threshold 4 models showed all students followed a single upward trajectory in all three cohorts, showing clear progression in competence over three clinical BDS years. A threshold 5 model produced two distinct trajectories, and in each cohort a 'better performing' trajectory was identified. Students allocated to the 'better performing' trajectories scored higher on average in the final examinations for cohort 2 (29% vs 18% (BDS4); 33% vs. 15% (BDS5)) and cohort 3 (19% vs. 16% (BDS4); 21% vs. 16% (BDS5)). Reliability for the undergraduate examinations was high for all three cohorts (≥0.8815) and did not change appreciably when longitudinal assessment was included. CONCLUSIONS: There is some evidence to support that longitudinal data have a degree of content and criterion validity for assessing the development of clinical competence in undergraduate dental students, which should increase confidence in decisions based on these data. The findings also provide a good foundation for subsequent research.

Adaptation to Virtual Assessment during the COVID-19 Pandemic: Clinical Case Presentation Examination.

BACKGROUND: Case presentation assessment is common in both medicine and dentistry and is known under various names depending on the country and institution. It relates mainly to aspects of diagnosis and treatment planning and is considered highly authentic and useful. The COVID-19 pandemic necessitated the movement of this assessment from face-to-face to online. The aim of this investigation was to explore the students' impressions of the two different examination modalities. With this information, a decision on future diets of this examination can be made to accommodate the students' perspectives. METHODS: Quantitative and qualitative data were gathered using an online, self-administered survey. RESULTS: The students were split 50/50 regarding which assessment modality they preferred. Overall, they considered the online examination to be fair, and the majority agreed that the online format allowed them to display their knowledge as well as face-to-face. CONCLUSIONS: The delivery of case presentation examination is possible online. An online case presentation is a fair, useful, and authentic assessment that is appropriate to the needs of the faculty and students. Satisfaction with the two possible methods of conducting this assessment suggests it would be reasonable to conduct this examination online in the future.

Pattern of pterygomaxillary disarticulation associated with Le Fort I maxillary osteotomy.

Pterygomaxillary disarticulation (PMD) contributes to surgical complications of Le Fort 1 osteotomy and is associated with undesirable fractures of the pterygoid plates. The aim of this paper was to investigate the patterns of PMD in Le Fort I osteotomies using Rowe's disimpaction forceps, and to evaluate correlations with age and anatomical measurements. Cone-beam computed tomography (CBCT) scans of 70 consecutive orthognathic patients were retrospectively evaluated to study four patterns of PMD: Type 1 - PMD at, or anterior to, the pterygomaxillary junction (PMJ); Type 2 - PMD posterior to the PMJ; Type 3 - PMJ separation with comminuted fracture of the pterygoid plates; Type 4 - disarticulation of the maxilla involving the pterygoid plates above the level of the osteotomy line. The preoperative anteroposterior and mediolateral thicknesses of the PMJ and the length of the medial and lateral pterygoid plates were assessed. Satisfactory PMD was achieved in all cases and no severe complications were reported, including vascular, dental, mucosal, or neural damage. The most common PMD was Type 1 (54.3%), followed by Type 2 (40%). Comminuted fracture of the pterygoid plates was limited to 5.7% of cases, and no Type 4 was detected. A weak correlation was detected between PMJ thickness and PMD pattern (p = 0.04). No statistically significant correlation was detected between patients' age and type of PMD. PMD of Le Fort I maxillary osteotomy using a Smith spreader and Rowe's disimpaction forceps proved safe, with minimal damage to the pterygoid plates.

Orthognathic patient perception of 3D facial soft tissue prediction planning.

The primary aim of this study was to explore patients' perceptions regarding the impact of 3D prediction planning (3D PP) of facial soft tissue changes following orthognathic surgery. The study was carried out on 30 patients who were shown photorealistic 3D soft tissue prediction planning before undergoing orthognathic surgery to demonstrate the expected facial changes. Distraction osteogenesis and cleft deformities were excluded from the study before consenting to surgery. Following surgery, the included patients were asked to complete a standard questionnaire to explore their perceptions regarding the impact, accuracy, and value of 3D prediction planning. The majority of the 30 participants perceived 3D PP to be beneficial in reducing their presurgical anxiety, increasing their motivation to undergo surgery, improving the accuracy of their surgical expectations, and enhancing doctor-patient communication. Most of the patients perceived their surgical soft tissue changes to be better than the predictions. Significant positive correlations were detected between satisfaction with the delivered service and the facility of seeing 3D PP (rs = 0.4; p = 0.034). Similarly, 3D PP improved patients' confidence in the surgical decision (rs = 0.4; p = 0.031), as well as increasing their motivation to undergo surgery (rs = 0.5; p = 0.010). 3D PP was found to be effective in improving the quality of orthognathic surgical care.

A novel surgical model for the preclinical assessment of the osseointegration of dental implants: a surgical protocol and pilot study results.

BACKGROUND: Dental implants are considered the gold standard replacement for missing natural teeth. The successful clinical performance of dental implants is due to their ability to osseointegrate with the surrounding bone. Most dental implants are manufactured from Titanium and it alloys. Titanium does however have some shortcomings so alternative materials are frequently being investigated. Effective preclinical studies are essential to transfer the innovations from the benchtop to the patients. Many preclinical studies are carried out in the extra-oral bones of small animal models to assess the osseointegration of the newly developed materials. This does not simulate the oral environment where the dental implants are subjected to several factors that influence osseointegration; therefore, they can have limited clinical value. AIM: This study aimed to develop an appropriate in-vivo model for dental implant research that mimic the clinical setting. The study evaluated the applicability of the new model and investigated the impact of the surgical procedure on animal welfare. MATERIALS AND METHODS: The model was developed in male New Zealand white rabbits. The implants were inserted in the extraction sockets of the secondary incisors in the maxilla. The model allows a split-mouth comparative analysis. The implants' osseointegration was assessed clinically, radiographically using micro-computed tomography (µ-CT), and histologically. A randomised, controlled split-mouth design was conducted in 6 rabbits. A total of twelve implants were inserted. In each rabbit, two implants; one experimental implant on one side, and one control implant on the other side were applied. Screw-shaped implants were used with a length of 8 mm and a diameter of 2 mm. RESULTS: All the rabbits tolerated the surgical procedure well. The osseointegration was confirmed clinically, histologically and radiographically. Quantitative assessment of bone volume and mineral density was measured in the peri-implant bone tissues. The findings suggest that the new preclinical model is excellent, facilitating a comprehensive evaluation of osseointegration of dental implants in translational research pertaining to the human application. CONCLUSION: The presented model proved to be safe, reproducible and required basic surgical skills to perform.

The Validation of an Innovative Method for 3D Capture and Analysis of the Nasolabial Region in Cleft Cases.

OBJECTIVE: To validate a newly developed method for capturing 3-dimensional (3D) images of the nasolabial region for assessing upper lip scarring and asymmetry in surgically managed unilateral cleft lip and palate (UCLP) cases. DESIGN: Validation study, single cohort. MATERIALS AND METHODS: Eighteen surgically managed UCLP cases were recruited, the nasolabial region of each face was scanned using an intraoral scanner (IOS) to produce 3D images. The images were manually segmented to allow the calculation of surface area of the scar and upper lip asymmetry. Five professionals and 5 lay assessors subjectively evaluated the same images and graded the upper lip scarring and asymmetry at 2 separate occasions. The relationship between the subjective and objective assessments was evaluated. RESULTS: Moderate correlation was found between subjective and objective evaluations of the upper lip scarring and total asymmetry. The captured 3D images were of good quality for the objective measurements of lip asymmetry and residual scarring. Moderate to strong correlations were detected between the 2 panels (T ranging between 0.5 and 0.9) with no significant difference (P > .05) in the mean score of the subjectively evaluated parameters. CONCLUSION: The IOS is a useful tool for the capture of the nasolabial morphology. The captured 3D images are a reliable source for measuring lip asymmetry and scar surface area. The method has sufficient validity for routine clinical use and for objective outcome measures of the surgical repair of cleft lip.

Engineered Coatings for Titanium Implants To Present Ultralow Doses of BMP-7.

The ongoing research to improve the clinical outcome of titanium implants has resulted in the implemetation of multiple approches to deliver osteogenic growth factors accelerating and sustaining osseointegration. Here we show the presentation of human bone morphogenetic protein 7 (BMP-7) adsorbed to titanium discs coated with poly(ethyl acrylate) (PEA). We have previously shown that PEA promotes fibronectin organization into nanonetworks exposing integrin- and growth-factor-binding domains, allowing a synergistic interaction at the integrin/growth factor receptor level. Here, titanium discs were coated with PEA and fibronectin and then decorated with ng/mL doses of BMP-7. Human mesenchymal stem cells were used to investigate cellular responses on these functionalized microenvironments. Cell adhesion, proliferation, and mineralization, as well as osteogenic markers expression (osteopontin and osteocalcin) revealed the ability of the system to be more potent in osteodifferentiation of the mesenchymal cells than combinations of titanium and BMP-7 in absence of PEA coatings. This work represents a novel strategy to improve the biological activity of titanium implants with BMP-7.

Replacement of the Distorted Dentition of the Cone-Beam Computed Tomography Scans for Orthognathic Surgery Planning.

PURPOSE: Cone-beam computed tomography (CBCT) does not record dental morphology accurately because of the scattering produced by metallic restorations and the reported magnification of the dentition. The aim of this study was the development and evaluation of a new method for the replacement of the distorted dentition of CBCT scans with a 3-dimensional (3D) dental image captured by a digital intraoral camera. MATERIALS AND METHODS: Six dried skulls with orthodontic brackets fixed on the teeth were used in this study. Three intraoral markers made of dental stone were constructed and attached to orthodontic brackets. The skulls were scanned by CBCT and the occlusal surfaces were captured using the TRIOS 3D intraoral scanner. The digital intraoral scan (IOS) was fused into the CBCT models. This produced a new composite digital model of the skull and the dentition. The skulls were scanned again using the commercially accurate Faro laser arm to produce the 3D model the skull and teeth gold standard for the assessment of the accuracy of the developed method. This was assessed by measuring the distance between the occlusal surfaces of the new composite model and the gold standard 3D laser produced model. RESULTS: The results showed the errors related to the superimposition of the intraoral image on the CBCT to replace the distorted dentition were 0.11 to 0.20 mm. CONCLUSION: The results of this novel method suggest that the dentition on the CBCT scan can be accurately replaced with the digital IOS image captured by an intraoral scanner to create a composite model that will improve the accuracy of digital orthognathic surgical planning and the fabrication of the guiding occlusal wafer.

The clinical application of rhBMP-7 for the reconstruction of alveolar cleft.

In this study, radiographic assessment was performed to find out the effectiveness of bone regeneration following the application of recombinant human bone morphogenetic protein 7 (rhBMP-7) for the reconstruction of alveolar cleft defects in 11 cases: nine unilateral and two bilateral alveolar clefs. Reconstruction of the alveolar cleft was performed by using 3.5 mg of rhBMP-7 (Osigraft OP1) on a type I collagen carrier. Radiographs were taken 6 months post operation using a Gendex Intraoral Unit with Agfa Dentus M2 Comfort occlusal film. The amount of bony infill was graded on a Kindelan four-point scale. The patients were followed up for an average of 6.6 years. Based on the radiographic analysis, eight out of the nine unilateral alveolar cleft cases received a score of grade I and one patient had a grade II score, using the Kindelan scale. In the two bilateral alveolar clefts, only one side had bone formation. The radiographic appearance showed a normal trabecular pattern similar to the adjacent bone. Thus, rhBMP-7 was radiographically and clinically successful in regenerating the bone at the alveolar cleft which resulted in shortening of the operation time, absence of donor-site morbidity and a shorter hospital stay. The promising results of this preliminary study should encourage a phase II trial to compare bone grafts with BMP for the reconstruction of alveolar defects.

Radiological assessment of bioengineered bone in a muscle flap for the reconstruction of critical-size mandibular defect.

This study presents a comprehensive radiographic evaluation of bone regeneration within a pedicled muscle flap for the reconstruction of critical size mandibular defect. The surgical defect (20 mm × 15 mm) was created in the mandible of ten experimental rabbits. The masseter muscle was adapted to fill the surgical defect, a combination of calcium sulphate/hydroxyapatite cement (CERAMENT™ |SPINE SUPPORT), BMP-7 and rabbit mesenchymal stromal cells (rMSCs) was injected inside the muscle tissue. Radiographic assessment was carried out on the day of surgery and at 4, 8, and 12 weeks postoperatively. At 12 weeks, the animals were sacrificed and cone beam computerized tomography (CBCT) scanning and micro-computed tomography (µ-CT) were carried out. Clinically, a clear layer of bone tissue was identified closely adherent to the border of the surgical defect. Sporadic radio-opaque areas within the surgical defect were detected radiographically. In comparison with the opposite non operated control side, the estimated quantitative scoring of the radio-opacity was 46.6% ± 15, the mean volume of the radio-opaque areas was 63.4% ± 20. Areas of a bone density higher than that of the mandibular bone (+35% ± 25%) were detected at the borders of the surgical defect. The micro-CT analysis revealed thinner trabeculae of the regenerated bone with a more condensed trabecular pattern than the surrounding native bone. These findings suggest a rapid deposition rate of the mineralised tissue and an active remodelling process of the newly regenerated bone within the muscle flap. The novel surgical model of this study has potential clinical application; the assessment of bone regeneration using the presented radiolographic protocol is descriptive and comprehensive. The findings of this research confirm the remarkable potential of local muscle flaps as local bioreactors to induce bone formation for reconstruction of maxillofacial bony defects.

The use of TriCalcium Phosphate (TCP) and stem cells for the regeneration of osteoperiosteal critical-size mandibular bony defects, an in vitro and preclinical study.

The investigation aims to assess the reconstruction of critical-size mandibular bone defects in rabbits using beta-Tricalcium Phosphate (ß-TCP) scaffolding loaded with stem cells. A 20 mm-long mandibular osteoperiosteal continuity defect was created in 8 New Zealand rabbits and filled with ß-TCP scaffolding. In 6 cases bone marrow stem cells (BMSCs) harvested, and enriched, from the posterior iliac crest of the same rabbit were seeded into the scaffolding, while a scaffold was used alone in two cases chosen at random. Radiographic analysis was carried out immediately following surgery and 4, 8 and 12 weeks postoperatively. Cone Beam CT (CBCT) scanning, biomechanical testing and histology assessments were carried out on the explanted mandibles three months postoperatively. The radiography showed minimal new bone formation in all the cases, with significant amounts of undegraded scaffold material visible. Sporadic areas of bone formation were seen, these did not bridge the gap of the created surgical defect. The mechanical properties of the regenerated bone were of an inferior quality when compared with that of the contralateral non-operated side. The addition of BMSCs to the biodegradable ß-TCP scaffold did not improve reconstruction of the created mandibular defect. Despite successful aspiration and culture of BMSCs, the survival of these cells in vivo was questionable.

Assessment of cellular viability on calcium sulphate/hydroxyapatite injectable scaffolds.

Cements for maxillofacial reconstruction of jaw defects through calcification of rotated muscle have been tested. The objective of this study was to investigate the visibility of loading of two types of commercially available cements, Cerament(™) Spine Support and Cerament Bone Void Filler with mesenchymal cells and cytokines (bone morphogenetic protein) to act as a biomimetic scaffolding for future clinical application. Determination of basic biocompatibility (cell viability) using methyl thiazolyl tetrazolium and live/dead assay was carried out using MG-63 cells at various time points. Next, in order to inform potential subsequent in vivo experiments, a collagen tissue mimic was used for characterization of rabbit mesenchymal stromal cells using immunofluorescent cytoskeleton staining, and simultaneous and then sequential injection of Cerament Spine Support cement and cells into collagen gels. Results indicated that Cerament Spine Support was more biocompatible and that sequential injection of cement and then rabbit mesenchymal stromal cells into the tissue mimics is an optimal approach for clinical applications.

Mandibular reconstruction in the rabbit using beta-tricalcium phosphate (ß-TCP) scaffolding and recombinant bone morphogenetic protein 7 (rhBMP-7) - histological, radiographic and mechanical evaluations.

This investigation assesses the histological, radiographic and mechanical properties of regenerated bone in a unilateral critical-size osteoperiosteal mandibular continuity defect in the rabbit model, following the application of beta-tricalcium phosphate (ß-TCP) scaffolding and recombinant human bone morphogenetic protein 7 (rhBMP-7). The study was carried out on nine cases; in six cases the critical-size defect was filled with rhBMP-7 in the ß-TCP scaffolding, and in three cases the ß-TCP was used alone. The cases were sacrificed 3 months post-operatively. Histologically the overall mean of the percentage of regenerated bone volume in the cases that received rhBMP-7 was 29.41% ± 6.25%, which was considerably greater than the 6.35% ± 3.08% in the cases treated with ß-TCP alone. Mechanical testing of the cases treated with rhBMP-7 gave failure moments (55 mNm-2.040 Nm) that were consistently greater than those treated with ß-TCP alone (0 mNm-48 mNm). In some cases the mechanical properties of the regenerated bone were comparable to those of untreated bone. RhBMP-7 in prefabricated ß-TCP scaffolding appeared, radiographically and histologically, to be an effective method for bone regeneration in mandibular critical-size defects in the rabbit model. This points towards possible future clinical applications.