Postoperative Cone-beam Computed Tomography Scans Research Articles

Layered deep learning for automatic mandibular segmentation in cone-beam computed tomography

ObjectiveTo develop and validate a layered deep learning algorithm which automatically creates three-dimensional (3D) surface models of the human mandible out of cone-beam computed tomography (CBCT) imaging. Materials & methodsTwo convolutional networks using a 3D U-Net architecture were combined and deployed in a cloud-based artificial intelligence (AI) model. The AI model was trained in two phases and iteratively improved to optimize the segmentation result using 160 anonymized full skull CBCT scans of orthognathic surgery patients (70 preoperative scans and 90 postoperative scans). Finally, the final AI model was tested by assessing timing, consistency, and accuracy on a separate testing dataset of 15 pre- and 15 postoperative full skull CBCT scans. The AI model was compared to user refined AI segmentations (RAI) and to semi-automatic segmentation (SA), which is the current clinical standard. The time needed for segmentation was measured in seconds. Intra- and inter-operator consistency were assessed to check if the segmentation protocols delivered reproducible results. The following consistency metrics were used: intersection over union (IoU), dice similarity coefficient (DSC), Hausdorff distance (HD), absolute volume difference and root mean square (RMS) distance. To evaluate the match of the AI and RAI results to those of the SA method, their accuracy was measured using IoU, DSC, HD, absolute volume difference and RMS distance. ResultsOn average, SA took 1218.4s. RAI showed a significant drop (p<0.0001) in timing to 456.5s (2.7-fold decrease). The AI method only took 17s (71.3-fold decrease). The average intra-operator IoU for RAI was 99.5% compared to 96.9% for SA. For inter-operator consistency, RAI scored an IoU of 99.6% compared to 94.6% for SA. The AI method was always consistent by default. In both the intra- and inter-operator consistency assessments, RAI outperformed SA on all metrics indicative of better consistency. With SA as the ground truth, AI and RAI scored an IoU of 94.6% and 94.4%, respectively. All accuracy metrics were similar for AI and RAI, meaning that both methods produce 3D models that closely match those produced by SA. ConclusionA layered 3D U-Net architecture deep learning algorithm, with and without additional user refinements, improves time-efficiency, reduces operator error, and provides excellent accuracy when benchmarked against the clinical standard. Clinical significanceSemi-automatic segmentation in CBCT imaging is time-consuming and allows user-induced errors. Layered convolutional neural networks using a 3D U-Net architecture allow direct segmentation of high-resolution CBCT images. This approach creates 3D mandibular models in a more time-efficient and consistent way. It is accurate when benchmarked to semi-automatic segmentation.

A cast-free approach to fabricating an implant-supported interim restoration: A dental technique

A cast-free approach is described to fabricate an implant-supported interim restoration by using the postoperative cone beam computed tomography (CBCT) scan to locate the placed implant. A postoperative intraoral scan was aligned to the postoperative CBCT scan through a dental implant planning software program. An attached interim abutment and implant analog complex was then scanned and superimposed on the placed implant in the postoperative CBCT scan. Once the best alignment was achieved, a virtual cast was generated, and an interim restoration with bilateral positioning wings was fabricated on the interim abutment and inserted during the second-stage surgery. This technique offers a cast-free approach to inserting an implant-supported interim restoration immediately after the second-stage surgery to guide the healing of the soft tissue that can minimize chairside time and optimize the clinical workflow.

Accuracy of haptic robotic guidance of dental implant surgery for completely edentulous arches

Statement of problemThe accuracy of single implant placement is critical, as errors may cause problems with vital structures intraoperatively, as well as postoperatively with the prostheses. These issues may be exacerbated in complete-arch edentulous treatments requiring relative accuracy among multiple implants, particularly with prefabricated prosthetic structures. PurposeThe purpose of this clinical study was to determine the accuracy of dental implant placement by using haptic robotic guidance in completely edentulous participants. Material and methodsIn a prospective single-arm clinical study, 5 qualified participants elected to receive dental implants placed by using haptic robotic guidance to restore either the maxillary or mandibular arch, or both, with complete-arch implant-supported prostheses. Three dual-arch participants and 2 single-arch participants resulted in 38 endosteal dental implants being placed. A virtual preoperative restorative and surgical plan was created before surgery. This plan was matched to the surgical workspace on the day of surgery by using a bone-mounted fiducial splint fabricated from a cone beam computed tomography (CBCT) scan. Intraoperatively, the surgeons maneuvered a handpiece attached to the robotic guidance arm, osteotomies were created with a haptically constrained handpiece, and the implants were placed with 3-dimensional haptic constraints as per the virtual plan. Postoperative CBCT scans allowed the evaluation of the deviations of the actual implant placement relative to the plan. ResultsTwenty-three implants were placed in the mandible and 15 in the maxilla. The mean ±standard deviation global angular deviation was 2.56 ±1.48 degrees, while the crown of the placed implant showed a deviation from the plan of 1.04 ±0.70 mm and the apex of 0.95 ±0.73 mm. The signed depth deviation was 0.42 ±0.46 mm proud. No adverse events were reported. ConclusionsThis clinical series for treating completely edentulous patients by using haptic robotic guidance was found to be safe and accurate. While further longer-term clinical studies are necessary to measure outcomes and to assess differences as compared with nonrobotic implementations, haptic robotic preparation appears to confer additional intraoperative advantages over other techniques for treating completely edentulous arches.

Three-dimensional pharyngeal airway space changes after bimaxillary advancement.

ABSTRACTIntroduction: The probability of improvement in the upper airway space (UAS) with orthognathic surgery should be considered during the surgical-orthodontic treatment decision, providing not only an esthetic, but also a functional benefit for the patient. Objective: The purpose of this study was to evaluate the 3D changes in the upper airway space after maxillomandibular advancement surgery (MMA). Methods: A retrospective analysis of 56 patients, 21 male and 35 female, with a mean age of 35.8 ± 10.7 years, who underwent MMA was performed. Pre- and postoperative cone-beam computed tomography scans (CBCT) were obtained for each patient, and the changes in the UAS were compared using Dolphin Imaging 11.7 software. Two parameters of the pharyngeal airway space (PAS) were measured: airway volume (AV) and minimum axial area (MAA). Paired t-test was used to compare the data between T0 and T1, at 5% significance level. Results: There was a statistically significant increase in the UAS. Bimaxillary advancement surgery increased the AV and the MAA, on average, by 73.6 ± 74.75% and 113.5 ± 123.87%, respectively. Conclusion: MMA surgery tends to cause significant increase in the UAS; however, this increase is largely variable.

In Vitro Transportation of Curved Canals Following Glide Path Preparation by PathFile and Scout RaCe Rotary Systems Versus Manual Instrumentation Using Cone-Beam Computed Tomography

Objectives:This study aimed to assess root canal transportation of curved canals following glide path preparation by PathFile and Scout RaCe rotary systems compared with manual instrumentation with stainless steel (SS) hand files using cone-beam computed tomography (CBCT).Materials and Methods:This in-vitro experimental study was conducted on extracted human mandibular first and second molars (n=51) with 25–45° canal curvature in their mesiobuccal root. All teeth underwent CBCT and were randomly divided into three groups (n=17). In group 1, a glide path in the mesiobuccal canal was created using SS hand files to the working length. In groups 2 and 3, after canal negotiation with a #8 SS hand file, a glide path was created with PathFile and Scout RaCe systems, respectively. The teeth underwent CBCT. Pre- and postoperative CBCT scans were compared to calculate the magnitude of canal transportation at 3, 6, and 9 mm from the apex. The results were analyzed using the Kruskal-Wallis and Freedman tests (P<0.05).Results:Manual instrumentation caused significantly higher canal transportation at 3 and 9 mm from the apex compared with rotary systems (P<0.05). PathFile and Scout RaCe were not significantly different at 3 (P=0.39) or 9 mm (P=0.99). No significant difference was noted in canal transportation among the three groups at 6 mm (P=0.15).Conclusion:Scout RaCe and PathFile cause less canal transportation than manual instrumentation with SS files when used for glide path preparation in curved canals, especially in the apical third.

THE EFFECT OF ISOLATED SEGMENTAL CHIN OSTEOTOMY (SCO) ON THE PHARYNGEAL AIRWAY SPACE

The chin affects facial esthetics and the harmony between frontal and lateral views and is one of the most important anatomic structures of the lower third of the face. Chin osteotomy is aimed at ensuring the harmonization of the facial profile by balancing the size and form of the lower third of the face. It is assumed that the isolated genioplasty surgery will improve the pharyngeal airway space (PAS) by promoting muscle changes, specifically by pulling forward the hyoid bone and decompressing the hypopharynx region. Two patients without obstructive sleep apnea syndrome (OSAS) underwent isolated chin osteotomy for esthetic purposes. Forward movement of the chin by the Pg point was 7 mm in one case and 11 mm in another case. They were evaluated by preoperative and postoperative cone-beam computed tomography scans. The upper airway space was subdivided into retropalatal and retroglossal spaces. After this, the upper airway space was analyzed through the following criteria: 1) three-dimensional, high-altitude, cross-sectional surfaces; 2) transverse and anteroposterior diameter changes. Isolated segmental genioplasty was used after precise virtual planning and resulted in the PAS increase only in one case. There was a relevant correlation between the vertical and horizontal chin change and the hypopharynx. There was an average of a 1.6-fold increase in the total volume of the upper airway space. The retroglossal space was increased 1.5-fold. In another case, there was no relevant correlation between the vertical and horizontal chin change and the PAS. Isolated segmental chin osteotomy provides predictable esthetic results in the correction of different mandible anterior deformities and may contribute to an increased volume and a morphologic airway change. Further studies should be conducted to evaluate the effect of isolated segmental genioplasty on the pharyngeal airway space.

Accuracy of a Novel Trace-Registration Method for Dynamic Navigation Surgery.

A technology called Trace Registration (TR) has been introduced to allow dynamic navigation of implant placement without the need for a thermoplastic stent. This study was undertaken in order to validate the accuracy of the TR protocol for dynamically guided implant surgery. A retrospective, observational, in vivo study was performed using dynamic navigation via the TR protocol. The preoperative cone beam computed tomography (CBCT) plan was superimposed and registered (aligned) with the postoperative CBCT scan to assess accuracy parameters. A total of 136 implants were placed in 59 partially edentulous arches. Mean deviation between the planned and actual position for all implants was 0.67 mm at the coronal level (entry point), 0.9 mm at the apical level, and 0.55 mm in depth, with an angle discrepancy of 2.50 degrees. Tracing 5 to 6 teeth tended to improve accuracy results compared to tracing 3 to 4 teeth. TR is as accurate as traditional registration and statically guided methods for implant surgery.

Computer-guided implant placement associated with computer-aided bone regeneration in the treatment of atrophied partially edentulous alveolar ridges: A proof-of-concept study

Background/purposeThe existing literature lacks information regarding the use of digital workflows during pre-surgical planning of implant rehabilitations in resorbed edentulous ridges. Thus, the aim was to evaluate the effectiveness of computer-guided implant placement and simultaneous computer-aided guided bone regeneration (GBR) in the treatment of atrophic posterior alveolar ridges. Materials and methodsPartially edentulous patients requiring GBR simultaneously to implant insertion were enrolled. Implant positions and the augmented missing bone were planned with specific software. A stereolithographic model of the grafted jaw was produced to transfer the virtual bone augmentation to the surgical field. A tooth-supported stent was used to guide implant insertion according to the virtual project. Visual analogue scales (VASs) were used to self-register postoperative pain, swelling, bleeding, and perception of the operation. Post-operative cone-beam computed tomography scan was superimposed to the virtual project to evaluate the accuracy of implant positions. ResultsOverall, 10 implants were placed in 5 patients. Healing proceeded uneventfully in all except one patient that showed a dehiscence of the lingual flap as early surgical complication. Nevertheless, complete filling of the bone defects was observed clinically and radiographically in all patients. Pain scored exceptionally high with respect to the other variables. Deviations of 0.73 ± 0.21 mm, 0.59 ± 0.28 mm, and 3.05° ± 1.22° were found at implant head, apex, and long-axis respectively. Distal implants showed higher angular deviations compared to mesial implants (p = 0.008). ConclusionComputer-guided approach provided encouraging results in terms of efficacy and accuracy. Conversely, patient-centered outcomes were below the expectations.

Effect of Le Fort I Maxillary Advancement and Clockwise Rotation on the Anteromedial Cheek Soft Tissue Change in Patients with Skeletal Class III Pattern and Midface Deficiency: A 3D Imaging-Based Prediction Study.

Patients with a skeletal Class III deformity may present with a concave contour of the anteromedial cheek region. Le Fort I maxillary advancement and rotational movements correct the problem but information on the impact on the anteromedial cheek soft tissue change has been insufficient to date. This three-dimensional (3D) imaging-assisted study assessed the effect of surgical maxillary advancement and clockwise rotational movements on the anteromedial cheek soft tissue change. Two-week preoperative and 6-month postoperative cone-beam computed tomography scans were obtained from 48 consecutive patients who received 3D-guided two-jaw orthognathic surgery for the correction of Class III malocclusion associated with a midface deficiency and concave facial profile. Postoperative 3D facial bone and soft tissue models were superimposed on the corresponding preoperative models. The region of interest at the anteromedial cheek area was defined. The 3D cheek volumetric change (mm3; postoperative minus preoperative models) and the preoperative surface area (mm2) were computed to estimate the average sagittal movement (mm). The 3D cheek mass position from orthognathic surgery-treated patients was compared with published 3D normative data. Surgical maxillary advancement (all p < 0.001) and maxillary rotation (all p < 0.006) had a significant effect on the 3D anteromedial cheek soft tissue change. In total, 78.9%, 78.8%, and 78.8% of the variation in the cheek soft tissue sagittal movement was explained by the variation in the maxillary advancement and rotation movements for the right, left, and total cheek regions, respectively. The multiple linear regression models defined ratio values (relationship) between the 3D cheek soft tissue sagittal movement and maxillary bone advancement and rotational movements of 0.627 and 0.070, respectively. Maxillary advancements of 3–4 mm and >4 mm resulted in a 3D cheek mass position (1.91 ± 0.53 mm and 2.36 ± 0.72 mm, respectively) similar (all p > 0.05) to the 3D norm value (2.15 ± 1.2 mm). This study showed that both Le Fort I maxillary advancement and rotational movements affect the anteromedial cheek soft tissue change, with the maxillary advancement movement presenting a larger effect on the cheek soft tissue movement than the maxillary rotational movement. These findings can be applied in future multidisciplinary-based decision-making processes for planning and executing orthognathic surgery.

Key factors for a successful surgical guide: A prospective pilot study

Aims: The aim of this prospective pilot study was to assess the effect of the variation factors starting from the impression technique to the surgery itself in the accuracy of the dental-supported stereolithographic surgical template in implant surgery. Methods and Materials: Eighteen tapered bone level Straumann implants were inserted in 12 partially edentulous patients. The pre- and post-operative cone-beam computed tomography scans were matched allowing comparison of the planned implants with the inserted ones, considering the coronal, apical, and the angular deviation values, according to different surgeons and different implant length. Results: A mean coronal variation of 1.15 ± 0.616 mm, an apical variation of 1.43 ± 0.77, mm and the angular variation of 2.90 ± 1.41were shown. These deviations were within the range reported by several systematic reviews with lower standard deviation from the mean values. Conclusion: Within the limitations of this study, the control of the variation key factors shows better results in guided surgery and with a higher consistency in the results even with different operators.

Effect of postoperative steroids on clinical outcomes and radiographic findings of horizontal alveolar ridge augmentation: A retrospective study.

The purpose of the study was to investigate if the prescription of oral postoperative steroids has an effect on clinical outcomes of horizontal ridge augmentation including implant placement and characteristics of the grafted bone. A retrospective chart review of 73 horizontal ridge augmentation cases was completed to assess the clinical outcomes, 53 of those cases were further assessed radiographically. Information was gathered regarding surgical technique, grafting materials, postoperative healing, medications used postoperatively, bone growth, and density changes as quantified on a cone-beam computed tomography (CBCT) scan. Statistical analysis was completed to identify whether the use of postoperative oral steroids altered outcomes. Steroids were used postoperatively following various horizontal ridge augmentation procedures. The use of tenting screws and resorbable membranes with a combination of osseous allograft and xenograft was used in 73 cases, 53 of which had preoperative and postoperative CBCT scans. Graft exposure occurred in five of the cases (9%), with the majority (n=4) among those with postoperative steroids, but this was not statistically significant (P-value=0.6510). Use of steroids was also not significantly associated with the number of courses of antibiotics (P-value>0.05), but it was significantly associated with increased number of postoperative visits (P-value<0.05). Among the subset for radiographic analysis (n=53), there were significant clinical and radiographic dimensional changes in alveolar ridge width with an average horizontal bone gain of 3.6mm. There were no statistically significant differences found in radiographic linear bone gain or clinical outcomes with the addition of steroids. A marginally statistically significant in the density of grafted bone was found with the addition of steroids (P-value>0.05). The prescription of postoperative steroids did not make a significant difference in clinical outcomes, success of implant placement or on radiographic assessment of grafted sites following horizontal alveolar ridge augmentation.

Landmark-Based Versus Voxel-Based 3-Dimensional Quantitative Analysis of Bimaxillary Osteotomies: A Comparative Study

We compared the accuracy of landmark-based and voxel-based 3-dimensional (3D) analysis to quantify the osseous movements of the maxilla and mandible after bimaxillary osteotomy. Cone beam computed tomography (CBCT) scans of 15 patients who had undergone bimaxillary osteotomy were randomly selected from the database. Before surgery, CBCT scanning was performed and an individualized 3D virtual surgical plan made for all patients. During surgery, the mandibular and maxillary segments were positioned as planned using 3D-milled interocclusal splints. At 1week after surgery, a postoperative CBCT scan was acquired. All pre- and postoperative CBCT data were rendered in 3 dimensions. The 3D virtual head models were superimposed on the cranial base. The 3D surgical movements of the maxilla and mandible were quantified using conventional landmark-based 3D cephalometric analyses and voxel-based 3D analyses (OrthoGnathicAnalyser). This process was performed by the same observer 3 times. The intraclass correlations and Bland-Altman plots were computed to quantify the measurement errors and reproducibility of both methods. High intraclass correlation coefficients were found for both methods. The voxel-based analyses yielded a higher correlation concerning the maxilla and distal mandible (r=0.98) compared with the landmark-based cephalometric analyses (r=0.90). The use of voxel-based 3D analyses in the quantification of osseous movements was more reliable and reproducible than the use of conventional landmark-based 3D analyses.

Preservation of residual hearing after cochlear implant surgery with slim modiolar electrode

PurposeTo evaluate the insertion results and hearing preservation of a novel slim modiolar electrode (SME) in patients with residual hearing.MethodsWe retrospectively collected the data from the medical files of 17 patients (18 ears) implanted with a SME. All patients had functional low frequency hearing (PTA (0.125–0.5 kHz) ≤ 80 dB HL). The insertion results were re-examined from the postoperative cone-beam computed tomography scans. Postoperative thresholds were obtained at the time of switch-on of the sound processors (mean 43 days) and at latest follow-up (mean 582 days). The speech recognition in noise was measured with the Finnish matrix sentence test preoperatively and at follow-up.ResultsThe mean insertion depth angle (IDA) was 395°. Neither scala dislocations nor tip fold over were detected. There were no total hearing losses. Functional low-frequency hearing was preserved in 15/18 (83%) ears at switch-on and in 14/17 (82%) ears at follow-up. According to HEARRING classification, 55% (10/18) had complete HP at switch-on and 41% (7/17) still at follow-up. Thirteen patients (14 ears) were initially fitted with electric–acoustic stimulation and seven patients (8 ears) continued to use it after follow-up.ConclusionsThe preliminary hearing preservation results with the SME were more favorable than reported for other perimodiolar electrodes. The results show that the array may also be feasible for electro-acoustic stimulation; it is beneficial in that it provides adequate cochlear coverage for pure electrical stimulation in the event of postoperative or progressive hearing loss.

Long-Term Postoperative Cone-Beam Computed Tomography Analysis of Secondary Bone Grafting in 79 Patients With Unrepaired Alveolar Clefts

This study used cone-beam computed tomography (CBCT) analysis to assess the long-term radiographic outcomes of early secondary alveolar bone grafting. The most recent postoperative CBCT scans of 79 alveolar cleft patients who underwent anterior iliac crest bone grafting by a single surgeon over a 6-year period and metall inclusion criteria were analyzed using a modified assessment tool. Clefts were measured vertically, horizontally, and superiorly in terms of nasal support and then assigned corresponding scores of 0 to 4 to help determine radiographic success. The sites were deemed poor (score of 0 or 1), acceptable (score≥2), or favorable (score≥3). Similarly, overall clefts (vertical plus horizontal scores) were classified as poor (score of 0 to 3), acceptable (score≥4), or favorable (score≥5). Statistical analysis was used to characterize patient demographic characteristics, to perform subgroup comparisons, and to identify factors specifically predictive of favorable outcomes. The study included 79 patients with a total of 105 clefts. Male patients comprised 60.8% of patients, and 32.9% of patients had a bilateral cleft. The average age at the time of surgery was 8years 0months, and the average time until the most recent postoperative CBCT scan was 2years 8months.The average scores were as follows: vertical, 2.9 (maximum score possible, 4); horizontal, 3.1 (maximum score possible, 4); nasal support, 2.7 (maximum score possible, 4); and overall cleft, 6.0 (maximum score possible, 8).All 79 patients were discharged on postoperative day 1, and the regraft rate was 0%. Multivariate analysis showed that younger patients had a significantly higher chance of achieving favorable results in terms of vertical scores (P=.0081) and overall cleft scores (P=.0204). The association between younger age and horizontal scores was marginally significant (P=.0667), but no significant association was found between age and nasal support. Younger patients have improved long-term radiographic success with grafted alveolar clefts. This finding supports performing anterior iliac crest bone grafting at a younger age in cleft lip patients.

Accuracy of implant position when placed using static computer-assisted implant surgical guides manufactured with two different optical scanning techniques: a randomized clinical trial

Data from cone beam computed tomography (CBCT) and optical scans (intraoral or model scanner) are required for computer-assisted implant surgery (CAIS). This study compared the accuracy of implant position when placed with CAIS guides produced by intraoral and extraoral (model) scanning. Forty-seven patients received 60 single implants by means of CAIS. Each implant was randomly assigned to either the intraoral group (n=30) (Trios Scanner, 3Shape) or extraoral group (n=30), in which stereolithographic surgical guides were manufactured after conventional impression and extraoral scanning of the stone model (D900L Lab Scanner, 3Shape). CBCT and surface scan data were imported into coDiagnostiX software for virtual implant position planning and surgical guide design. Postoperative CBCT scans were obtained. Software was used to compare the deviation between the planned and final positions. Average deviation for the intraoral vs. model scan groups was 2.42°±1.47° vs. 3.23°±2.09° for implant angle, 0.87±0.49mm vs. 1.01±0.56mm for implant platform, and 1.10±0.53mm vs. 1.38±0.68mm for implant apex; there was no statistically significant difference between the groups (P>0.05). CAIS conducted with stereolithographic guides manufactured by means of intraoral or extraoral scans appears to result in equal accuracy of implant positioning.

Accuracy of Computer-Guided Template-Based Implant Surgery: A Computed Tomography-Based Clinical Follow-Up Study.

The aim of this clinical study was to analyze the accuracy of computer-guided implant surgery. Assisted by computed tomography (CT)-based planning software and navigational templates, 16 patients successfully received 26 dental implants. Each implant parameter (a-d) was calculated based on superimposed preoperative and postoperative cone beam CT scans: (a) deviation at entry point; (b) deviation at apex; (c) angular deviation; and (d) depth deviation. Mean central deviation at implant entry point and apex was 0.91 mm (standard error [SE] = 0.11 mm; 95% confidence interval [CI]: 0.69-1.13) and 1.22 mm (SE = 0.11 mm; 95% CI: 0.99-1.45), respectively. Mean angulation deviation was 4.11 degrees (SE = 0.52 degrees; 95% CI: 3.04-5.17) and the average depth deviation was 0.65 mm (SE = 0.11 mm; 95% CI: 0.42-0.87). For the total number of implants placed, the maximum error was 2.34 mm at entry point, 2.71 mm at apex, 9.44 degrees in angular deviation, and 2.00 mm in depth deviation. Great accuracy was reached even in advanced cases with prior bone augmentation and complex traumas. This leads to the conclusion that particularly in advanced cases, computer-guided implantation can be beneficial.

Immediate nonfunctional loading of implants placed simultaneously using computer-guided flapless maxillary crestal sinus augmentation with bone morphogenetic protein-2/collagen matrix.

Immediate loading has shown positive results for total, partial, or single edentulism. The effects of BMP-2 addition to graft materials on bone formation and implant stability in the early stages of healing have rarely been studied, especially in patients with severely atrophic maxillae. To evaluate the effects of simultaneously placed immediate non-functional loaded implants and bone morphogenetic protein-2 (BMP-2)-loaded Bio-Oss collagen, on bone formation and implant stability during the early healing stages of patients with a severely atrophic posterior maxilla using crestal approach. Thirty-three cases presenting posterior maxillary residual alveolar bone height of 1-3 mm were evaluated. Flapless crestal sinus augmentation surgery was performed using BMP-2-loaded Bio-Oss collagen, with non-functional implants immediately loaded after surgery. The bone height was assessed using preoperative and postoperative cone beam computed tomography (CBCT). Bone density of the sinus graft sites and implant stability (after 3 months) were evaluated using postoperative CBCT scans and Periotest, respectively. The periodontal parameters and marginal bone loss around the implant were checked after 37.3 months of final prosthesis. The survival rate of the implants was 100% and the gingiva around the implants remained healthy. All implants remained integrated, and all sinus grafts showed radiographic bone formation. The results indicated high level of bone density and good implant stability, showing minimal marginal bone loss after 37.3 months. This technique could be used in the posterior maxillary region exhibiting poor bone quantity.

An average three-dimensional virtual human skull for a template-assisted maxillofacial surgery.

Although many advances have been made in three-dimensional virtual planning in maxillofacial surgery, facial harmony is still difficult to achieve and is heavily dependent on the surgeon's experience. The aim of the study is to present a method to build up an average three-dimensional virtual human skull to be used as a reference template for bone repositioning and reconstruction during maxillofacial surgical interventions. A total of 20 patients (10 females and 10 males) were selected for the optimal outcome after orthognathic surgery. Postoperative cone-beam computed tomography scans were collected and processed in order to obtain three-dimensional digital models of each skull. For male and female subgroups, the three-dimensional skull models were registered and an average three-dimensional virtual skull model was computed. Deviation color maps were calculated to show differences between each postoperative skull model in the population and the obtained average three-dimensional skull. A clinical use case of genioplasty treatment assisted by the provided average three-dimensional skull template was presented. The overall mean deviation from the average three-dimensional skull model was 1.3 ± 0.6 and 1.6 ± 0.5 mm in male and female subgroups, respectively. For both groups, the greatest deviations were at the area of the mandible, while almost no deviation was found at the zygomatic and orbital areas. In the presented use case, the female average three-dimensional skull model was effectively used for guiding surgical planning. The presented method of obtaining an average three-dimensional virtual human skull may offer the interesting perspective of performing an innovative template-assisted maxillofacial surgery.

Effects of different loading protocols on the bone remodeling volume of immediate maxillary single implants: A 2- to 3-year follow-up.

The purpose of this study was to assess the effect of different loading protocols (immediate or delayed) on bone volume remodeling of an immediate implant-supported single crown in the maxilla with a follow-up from 2 to 3 years. Patients presenting a failing tooth have been rehabilitated with implant-supported single crowns. Data of patients with a survey from 2 to 3 years after baseline surgery were retrospectively acquired. One implant per patient was randomly selected during data analysis and assigned to one of two predictor groups: the loading protocol, 9 immediate vs 13 delayed loading; and tooth position, 9 incisors vs 9 canines. Cumulative survival rates were recorded; loss of crestal bone volume was assessed with cone beam computed tomography (CBCT) by means of software that superimposed the preoperative and postoperative CBCT scan data (Matrix Laboratory) and by destascan software. Twenty-two patients were enrolled. No postoperative complications or implant failures were recorded. Bone volume loss from the 2- to 3-year follow-up period ranged between 19.1% and 22.0%, without significant differences between the two loading protocols. Irrespective of the tooth site, intragroup analyses revealed the presence of significant differences between preoperative and postoperative time evaluations for all the analyzed groups and subgroups. Volumes at baseline (ranging between 0.546 cc and 0.553 cc) recorded significant loss of approximately 110 mm3 (P values ≤ .0001) for both loading protocols. The volume at the postoperative evaluation ranged between 0.428 cc and 0.442 cc. Considering tooth site in the analysis, the subgroups showed similar behaviors at the crestal bone level. However, bone loss at the apex of the implant appeared to be lower for incisors than canines. This study attested that the loss of crestal bone around an immediate implant-supported single crown depended on neither the loading protocol nor the tooth site.

Canal transportation caused by one single-file and two multiple-file rotary systems: A comparative study using cone-beam computed tomography

Aim: This ex-vivo study aimed to compare canal transportation in mesio-buccal canal of mandibular first molars prepared with Mtwo and Revo-S multi-file and Neoniti single-file nickel[18TD$DIF]—titanium (Ni—Ti) rotary systems using cone-beam computed tomography (CBCT). Methodology: CBCTscans were obtained from 60 extracted mandibular first molars and the teeth were randomly divided into three groups. Mesio-buccal canal of mesial root was prepared with Revo-S, Neoniti or Mtwo rotary systems according to the instructions of the manufacturers. Postoperative CBCT scans were also obtained. A single operator performed canal preparations while another operator blinded to the group allocation of teeth did the measurements. Data were analyzed using SPSS 20. The mean and standard deviation (SD) of the amount of canal transportation were calculated and compared between the groups using the Friedman test ([19TD$DIF]P 0.05). Results: No significant difference was noted in canal transportation among the groups in the middle and apical third ([20TD$DIF]P &gt; 0.05). The rotary single-file instrument caused significantly greater canal transportation in the coronal third. Conclusion: No significant difference exists among different rotary systems in the amount of canal transportation caused in the middle and apical third of the mesio-buccal canal in mandibular first molars. Although all rotary files caused some degrees of canal transportation, the rotary single-file instrument caused significantly greater canal transportation than the multiple-file sequences in the coronal third.