Splintless surgery using patient-specific osteosynthesis in Le Fort I osteotomies: a randomized controlled multi-centre trial

The accuracy of orthognathic surgery has improved with three-dimensional virtual planning. The translation of the planning to the surgical result is reported to vary by >2 mm. The aim of this randomized controlled multi-centre trial was to determine whether the use of splintless patient-specific osteosynthesis can improve the accuracy of maxillary translation. Patients requiring a Le Fort I osteotomy were included in the trial. The intervention group was treated using patient-specific osteosynthesis and the control group with conventional osteosynthesis and splint-based positioning. Fifty-eight patients completed the study protocol, 27 in the patient-specific osteosynthesis group and 31 in the control group. The per protocol median anteroposterior deviation was found to be 1.05 mm (interquartile range (IQR) 0.45–2.72 mm) in the patient-specific osteosynthesis group and 1.74 mm (IQR 1.02–3.02 mm) in the control group. The cranial–caudal deviation was 0.87 mm (IQR 0.49–1.44 mm) and 0.98 mm (IQR 0.28–2.10 mm), respectively, whereas the left–right translation deviation was 0.46 mm (IQR 0.19–0.96 mm) in the patient-specific osteosynthesis group and 1.07 mm (IQR 0.62–1.55 mm) in the control group. The splintless patient-specific osteosynthesis method improves the accuracy of maxillary translations in orthognathic surgery and is clinically relevant for planned anteroposterior translations of more than 3.70 mm.     

Evaluating the accuracy of resection planes in mandibular surgery using a preoperative,intraoperative, and postoperative approach

In mandibular surgery, three-dimensionally printed patient-specific cutting guides are used to translate the preoperative virtually planned resection planes to the operating room. This study was performed to determine whether cutting guides are positioned according to the virtual plan and to compare the intraoperative position of the cutting guide with the resection performed. Nine patients were included. The exact positions of the resection planes were planned virtually and a patient-specific cutting guide was designed and printed. After surgical placement of the cutting guide, intraoperative cone beam computed tomography (CBCT) was performed. Postoperative CT was used to obtain the final resection planes. Distances and yaw and pitch angles between the preoperative, intraoperative, and postoperative resection planes were calculated. Cutting guides were positioned on the mandible with millimetre accuracy. Anterior osteotomies were performed more accurately than posterior osteotomies (intraoperatively positioned and final resection planes differed by 1.2 ± 1.0 mm, 4.9 ± 6.6°, and 1.8 ± 1.5°, respectively, and by 2.2 ± 0.9 mm, 9.3 ± 9°, and 8.3 ± 6.5° respectively). Differences between intraoperatively planned and final resection planes imply a directional freedom of the saw through the saw slots. Since cutting guides are positioned with millimetre accuracy compared to the virtual plan, the design of the saw slots in the cutting guides needs improvement to allow more accurate resections.     

Evaluation of fit feasibility of stock total joint replacement in temporomandibular joint ankylosis patients

Long standing adult temporomandibular joint ankylosis (TMJA) results in smaller ramal height, and warped and undulated ramus. Despite the efforts made to standardise the sizes available in stock joint (Zimmer Biomet®), the system causes fit challenges in TMJA patients. The aim of the study was to evaluate the virtual feasibility of stock prostheses in TMJA patients. The data included amount of bone contouring for fossa placement, available ramal length, length discrepancy if placed straight, angulation of mandibular component required to adapt to the bone, and mediolateral fit discrepancy. CT data of 50 TMJA patients (71 joints; unilateral, n = 29; bilateral, n = 21; male, n = 33; female, n = 17) with mean age of 24.26 ± 8.88 years were included. 53 joints required more than 3 mm lateral bone reduction for fossa placement. The ramal length were categorised into ranges 35–40 mm (n = 15), 41–45 mm (n = 14), 46–50 mm (n = 28) and >50 mm (n = 14). Correlation between the age of occurrence of ankylosis and ramal length using the Pearson correlation coefficient revealed a positive correlation (r = 0.38, p = 0.001). Length discrepancy, angulation of mandibular component, and mediolateral fit discrepancy decreases as the ramal length increases. Only 14 joints had appropriate fit of stock prostheses while the remaining 57 joints warranted compromised placement. Even the smallest available stock mandibular component (45 mm) had a compromised fit in terms of length and adaptability on the lateral aspect of ramus. The study concludes that a short ramus is mostly limiting factor in using stock prosthesis in TMJA patients. There is a need for still smaller size stock prostheses.     

The 3D-printed miniplate-jig system: a new,rapid, precise,and user-friendly approach to miniplate fixation of free-tissue mandibular reconstructions

Patient-specific, additively manufactured (printed) titanium reconstruction plates have been widely used to improve accuracy and efficiency of fibular flap reconstruction of the mandible. Miniplates possess some potential advantages over single-piece reconstruction plates, however multiple-miniplate fixation can be more technically demanding and may lengthen the duration of surgery. Furthermore, incremental angulation errors in screw placement for each miniplate could compromise overall dimensional accuracy of the neomandibular reconstruction. This preliminary article reports the first clinical use of a new patient-specific, printed titanium miniplate-jig system in a patient undergoing hemimandibulectomy for osteoradionecrosis of the mandible with fibular flap reconstruction. Our initial experience with the new device and technique demonstrates a quick, user friendly, and precise method for the placement and fixation of multiple miniplates in fibular-flap reconstruction of the mandible.     

Relationship between the canthal–tragus distance and the puncture point in temporomandibular joint arthroscopy

This study investigated whether a relationship exists between the length of the canthal–tragus line and the distance from the tragus at which the puncture point for arthroscope insertion should be made. On one side of 11 cadaver heads, a puncture point was marked 7 mm from the midtragus and 2 mm below the canthal–tragus line. On the other side, the distances were 10 mm and 2 mm, respectively. The arthroscope trocar and cannula were inserted at the marked points. The anatomical location of the arthroscope after insertion was confirmed by open dissection with the arthroscope in place. Following dissection, the canthal–tragus line was measured on each side of the cadaver's head. For measurements >70 mm, puncture points 10 mm from the midtragus led to insertion of the arthroscope inside the upper joint compartment. For measurements ≤70 mm, puncture points 7 mm from the midtragus led to insertion of the arthroscope inside the upper joint compartment. This suggests that for canthal–tragus distances of >70 mm, the arthroscope should be inserted 10 mm from the midtragus and for distances ≤70 mm it should be inserted at 7 mm for the greatest likelihood of entering the upper joint compartment of the TMJ.     

Anatomic measurement of the depth and location of the sublingual fossa

The purpose of this study was to measure the depth and location of the sublingual fossa, a potential site of sublingual bleeding/lingual cortical perforation during endosseous implant placement in the mandibular interforaminal region (MIR), to clarify anatomical variation. Using the mandibles of 37 Japanese cadavers, the lingual depth (LD) between the lingual surface and the line perpendicular to the inferior margin of the mandible (IMM), as well as the vertical distance (VD) between the lingual surface and the IMM or the mental foramen (MF) level, were measured at defined points and lines within the MIR. The definite sublingual fossa (SF) was identified by the LD (≥1.0 mm) and the VD, and the depth and location of the SF were determined. The depth ranged between 1.0 mm and 5.8 mm, and the vertical location ranged between 9.2 mm and 15.7 mm from the IMM and between 2.2 mm and 6.1 mm from the MF level. These results revealed certain tendencies in the depth and location of the SF but the variation was substantial. The SF should be identified in each case as accurately as possible by CT before implant placement in the MIR to minimize the risk of the potential complications.     

Three-dimensional soft tissue prediction in orthognathic surgery: a clinical comparison of Dolphin,ProPlan CMF,and probabilistic finite element modelling

Three-dimensional surgical planning is used widely in orthognathic surgery. Although numerous computer programs exist, the accuracy of soft tissue prediction remains uncertain. The purpose of this study was to compare the prediction accuracy of Dolphin, ProPlan CMF, and a probabilistic finite element method (PFEM). Seven patients (mean age 18 years; five female) who had undergone Le Fort I osteotomy with preoperative and 1-year postoperative cone beam computed tomography (CBCT) were included. The three programs were used for soft tissue prediction using planned and postoperative maxillary position, and these were compared to postoperative CBCT. Accurate predictions were obtained with each program, indicated by root mean square distances: RMS_Dolphin = 1.8 ± 0.8 mm, RMS_ProPlan = 1.2 ± 0.4 mm, and RMS_PFEM = 1.3 ± 0.4 mm. Dolphin utilizes a landmark-based algorithm allowing for patient-specific bone-to-soft tissue ratios, which works well for cephalometric radiographs but has limited three-dimensional accuracy, whilst ProPlan and PFEM provide better three-dimensional predictions with continuous displacements. Patient or population-specific material properties can be defined in PFEM, while no soft tissue parameters are adjustable in ProPlan. Important clinical considerations are the topological differences between predictions due to the three algorithms, the non-negligible influence of the mismatch between planned and postoperative maxillary position, and the learning curve associated with sophisticated programs like PFEM.     

Immediate dental implant placement with a horizontal gap more than two millimetres: a randomized clinical trial

The purpose of this study was to evaluate the horizontal dimensional changes in buccal alveolar bone immediately after dental implant placement in the upper premolar area with horizontal gaps >2 mm. A total of 48 patients were enrolled in this randomized clinical trial and were randomly assigned to one of three groups. Group I (flap with graft; n = 16) patients received an immediate implant with bone graft, membrane, and primary flap closure. Group II (flap without graft; n = 16) patients received an immediate implant with primary flap closure only. Group III (flapless without graft; n = 16) patients received an immediate implant without graft, membrane, or primary closure. Cone beam computed tomography (CBCT) scans were obtained preoperatively, immediately after implant placement, and at 6 months postoperative to evaluate horizontal dimensional changes in the buccal alveolar bone. Pain intensity was measured using a numerical rating scale. CBCT examinations revealed that bone had filled the horizontal gap in all three groups. Group II showed the greatest horizontal dimensional changes in the buccal alveolar bone, followed by group I. The least amount of change was recorded for group III. Furthermore, significantly less postoperative pain was recorded in group III when compared to the other groups. Short-term results suggest that the ‘flapless without graft’ technique shows similar results to the ‘flap with graft technique’ for immediate implant placement in the maxillary premolar extraction site with a horizontal gap >2 mm, when the bone plate is intact.     

Will they fit? Determinants of the adaptability of stock TMJ prostheses where custom TMJ prostheses were utilized

Currently only two alloplastic temporomandibular joint (TMJ) total joint replacement (TJR) systems are available in the United States. The aim of this study was to define variables that determine whether a Biomet stock prosthesis could have been used to reconstruct a TMJ previously reconstructed with a TMJ Concepts patient-fitted prosthesis. All of the TMJ Concepts prostheses placed between 2010 and 2018 at the University of Texas – Health at San Antonio were analyzed retrospectively. There were 128 cases (241 joints) with intact stereolithographic models analyzed for successful adaptation of the Biomet stock TMJ prosthesis. Anatomical, demographic, etiological, and perioperative data were gathered for each joint to investigate possible causes of failure of stock adaptation. The majority of joints, 74% (178/241), could have had a stock prosthesis adapt. All joints with ≥40 mm gap arthroplasty failed stock prosthesis adaptation. Only 50% (32/64) of the joints with at least one previous open TMJ surgery and 60% (58/96) of the joints with concomitant orthognathic surgery could have had a stock TMJ prosthesis. The stock prosthesis could not be adapted for any of the patients requiring TMJ replacement for congenital disorders or those requiring TMJ salvage. Overall, the majority of cases treated with a patient-specific TMJ TJR could have been treated with a stock prosthesis.     

The intrinsic error of a stereolithographic surgical template in implant guided surgery

The aim of the present study was to assess the clinical relevance of the potential mechanical error (intrinsic error) caused by the cylinder-burr gap in a ‘single type’ stereolithographic surgical template in implant guided surgery. 129 implants were inserted in 12 patients using 18 templates. The pre- and postoperative computed tomography (CT) scans were matched allowing comparison of the planned implants with the placed ones. Considering only the angular deviation values, the t test was used to determine the influence of the guide fixation and the arch of support on accuracy values. The Pearson correlation coefficient was used to correlate angular deviation and bone density. The intrinsic error was mathematically evaluated. t test results indicated that the use of fixing screws (P = 009) and the upper arch support (P = 027) resulted in better accuracy. The Pearson correlation coefficient (0.229) indicated a significant linear correlation between angular deviations and bone density (P = 009). A mean intrinsic error of 2.57 was mathematically determined considering only the angular deviation, as it was not influenced by other variables. The intrinsic error is a significant factor compared to all the variables that could potentially affect the accuracy of computer-aided implant placement.     

Analysis of outcomes after revision replacement of failed total temporomandibular joint prostheses

End-stage disease of the temporomandibular joint (TMJ) can be managed successfully with alloplastic total replacements, but these can fail because of allergy, infection, wear, fracture, and heterotopic development of bone. We prospectively reviewed the outcome data of all patients who required revision of previously placed replacement joints between 2004 and 2016. Data included pain and diet scores using 100 mm visual analogue scales (VAS), and interincisal distance recorded before, and at six weeks, six months and 12 months after operation. The reasons for failure and the number of previous procedures were also noted.Twenty patients (26 joints) had revisions. The reasons included infection (n = 9), reankylosis (n = 5), wear of the existing prosthesis (n = 2), fracture of the prosthesis (n = 2), foreign body reaction (n = 1), and allergy to the prosthesis (n = 1). The mean (range) age of the patients was 53.3 (47-68) years, and 15 were female and five male. Preoperatively, the mean (SD) pain score was 73.1 (22.4), mouth opening was 20.9 (10.2) mm, and diet score 41.7 (23.6). At 12-month follow up, all the measurements had improved significantly (p ≤ 0.05), with the pain score improving to a mean (SD) of 18.4 (25.2), mouth opening to 32.2 (9.3) mm, and diet score to 89.4 (18.5). Revision replacements done by an experienced team result in considerably improved outcomes with limited complications, but the improvements in function and pain are not as marked as they are after primary replacement.     

Non invasive and surgical measurement of length of soft tissue from the tip of interdental papilla to the alveolar crest

BackgroundVarious methods, including clinical and radiographic techniques, can be used to assess periodontal regeneration in interproximal areas. The goal of the present study was to compare the papilla length relative to the alveolar bone crest measured by clinical, intrasurgical, and radiographic techniques.Materials and methodsThe study sample included 250 interproximal papillae in 68 patients with generalized chronic periodontitis. The papilla length from the alveolar bone crest was measured clinically (as the actual papilla length, APL), intrasurgically (as the bone probing length, BPL), and radiographically (as the radiographic bone length, RBL). Measurements were standardized by using acrylic resin stents, XCP rinn, a paralleling technique, and/or a radiographic grid.ResultsThe mean (± standard deviation) for RBL was 4.9 ± 0.8 mm, BPL was 5.1 ± 0.6 mm, and APL was 5.1 ± 0.6 mm. Correlations between RBL and APL and between BPL and APL were 0.918 and 0.943, respectively (both P < 0.01).ConclusionsIf the clinical recordings are appropriately standardized, then noninvasive radiographic methods can be used to evaluate the papilla length with good accuracy.     

One-step lateral window approach for removal of benign minor sinus pathologies combined with transcrestal sinus floor elevation without bone grafts: a retrospective study

The aim of this study was to evaluate the clinical and radiographic outcomes of a lateral window approach for removal of benign minor sinus pathologies combined with transcrestal sinus floor elevation. From 2014 to 2018, all patients who received sinus pathology removal via a lateral window approach combined with transcrestal sinus floor elevation were screened. The serous exudate or minor sinus pathology was drained or removed via lateral window approach. Subsequently, transcrestal sinus floor elevation without grafting and simultaneous implant placement were performed. Panoramic radiographs and cone-beam computed tomography were taken preoperatively, immediately after surgery, and after prosthesis delivery. Twelve patients were included in this study. The decrease in Schneiderian membrane thickness was statistically significant (P < 0.001). Endo-sinus bone formation was observed on the buccal (1.35 ± 2.31 mm) and palatal (1.61 ± 2.65 mm) sites of the implant. The implant survival rate was 100%. All implants survived for an average of 21.83 ± 11.11 months. Within the limitations of this study, we suggest that the lateral window approach for minor sinus pathology removal combined with transcrestal sinus floor elevation has several advantages including endo-sinus bone gain without bone graft, minimal patient discomfort, reduced postoperative complications and shorter treatment period.     

Accuracy of Le Fort I osteotomy with combined computer-aided design/computer-aided manufacturing technology and mixed reality

The aim of this study was to verify the reproducibility and accuracy of preoperative planning in maxilla repositioning surgery performed with the use of computer-aided design/manufacturing technologies and mixed reality surgical navigation, using new registration markers and the HoloLens headset. Eighteen patients with a mean age of 26.0 years were included. Postoperative evaluations were conducted by comparing the preoperative virtual operation three-dimensional image (Tv) with the 1-month postoperative computed tomography image (T₁). The three-dimensional surface analysis errors ranged from 79.9% to 97.1%, with an average error of 90.3%. In the point-based analysis, the errors at each point on the XYZ axes were calculated for Tv and T₁ in all cases. The median signed value deviation of all calculated points on the XYZ axes was ?0.03 mm (range ?2.93 mm to 3.93 mm). The median absolute value deviation of all calculated points on the XYZ axes was 0.38 mm (range 0 mm to 3.93 mm). There were no statistically significant differences between any of the points on any of the axes. These values indicate that the method used was able to reproduce the maxilla position with high accuracy.     

Can an entry-level 3D printer create high-quality anatomical models? Accuracy assessment of mandibular models printed by a desktop 3D printer and a professional device

This study was performed to determine whether an in-house printed mandible model is sufficiently accurate for daily clinical practice. Ten example mandible models were produced with a desktop 3D printer (fused filament fabrication, FFF) and compared with 10 equivalent mandible models fabricated using a professional-grade 3D printer (selective laser sintering, SLS). To determine the precision of the printed models, each model was scanned with an optical scanner. Subsequently, every model was compared to its original standard tessellation language (STL) file and to its corresponding analogue. Mean ± standard deviation and median (interquartile range) differences were calculated. Overall these were −0.019 ± 0.219 mm and −0.007 (−0.129 to 0.107) mm for all 10 pairs. Furthermore, correlation of all printed models to their original STL files showed a high level of accuracy. Comparison of the SLS models with their STL files revealed a mean difference of −0.036 ± 0.114 mm and median difference of −0.028 (−0.093 to 0.030) mm. Comparison of the FFF models with their STL files yielded a mean difference of −0.055 ± 0.227 mm and median difference of −0.022 (−0.153 to 0.065) mm. The study findings confirm that in-house 3D printed mandible models are economically favourable as well as suitable substitutes for professional-grade models, in particular considering the geometric aspects.     

The virtual human face: Superimposing the simultaneously captured 3D photorealistic skin surface of the face on the untextured skin image of the CBCT scan

The aim of this study was to evaluate the impact of simultaneous capture of the three-dimensional (3D) surface of the face and cone beam computed tomography (CBCT) scan of the skull on the accuracy of their registration and superimposition. 3D facial images were acquired in 14 patients using the Di3d (Dimensional Imaging, UK) imaging system and i-CAT CBCT scanner. One stereophotogrammetry image was captured at the same time as the CBCT and another 1 h later. The two stereophotographs were individually superimposed over the CBCT using VRmesh. Seven patches were isolated on the final merged surfaces. For the whole face and each individual patch: maximum and minimum range of deviation between surfaces; absolute average distance between surfaces; and standard deviation for the 90th percentile of the distance errors were calculated. The superimposition errors of the whole face for both captures revealed statistically significant differences (P = 0.00081). The absolute average distances in both separate and simultaneous captures were 0.47 and 0.27 mm, respectively. The level of superimposition accuracy in patches from separate captures was 0.3–0.9 mm, while that of simultaneous captures was 0.4 mm. Simultaneous capture of Di3d and CBCT images significantly improved the accuracy of superimposition of these image modalities.     

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 ± 0.49 mm vs. 1.01 ± 0.56 mm for implant platform, and 1.10 ± 0.53 mm vs. 1.38 ± 0.68 mm 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.     

A novel ‘surgeon-dominated’ approach to the design of 3D-printed patient-specific surgical plates in mandibular reconstruction: a proof-of-concept study

Three-dimensionally (3D) printed patient-specific surgical plates have been proposed to facilitate mandibular reconstruction and are attracting extensive attention. We have recently reported the high accuracy of 3D-printed patient-specific surgical plates used in head and neck reconstruction. Based on this previous work, the current study proposes a novel ‘surgeon-dominated’ approach to the design of 3D-printed patient-specific surgical plates. The aim of this proof-of-concept study was to explore the workflow and technical procedures of the surgeon-dominated approach. The workflow includes virtual surgery, the design and printing of patient-specific surgical devices, and real surgery. The prototype of the patient-specific surgical plate was designed by surgeons and further optimized for 3D printing by engineers. Different types of mandibular defect were tested to confirm the wide applicability of this approach. Cases in which this approach was used were reviewed and the duration of time spent on each case studied. Based on a total of 16 patients, the time spent on virtual surgery and plate design was 18.83 ± 13.19 hours, and the time taken for 3D printing, post-processing, and product delivery was 162.9 ± 55.15 hours. Therefore, this novel surgeon-dominated approach is feasible and time-saving, which would likely promote the wide application of patient-specific surgical plates and lead to a new era of ‘digitization and precision’ in mandibular reconstruction.ClinicalTrials.gov registration: NCT03057223.     

Palatal orthodontic miniscrew insertion using a CAD-CAM surgical guide: description of a technique

The aim of this report was to describe a new computer-guided technique for a controlled site preparation and palatal orthodontic miniscrew insertion using a dedicated software. A surgical guide was designed after planning the appropriate insertion sites on three-dimensional images created by the fusion of cone-beam computed tomography (CBCT) and digital dental model images. Pre- and postoperative CBCT images were compared and the angular, coronal, and apical deviations between the planned and the placed miniscrews were calculated. The mean coronal and apical deviations were 1.38 mm (range: 3.48–0.15 mm; standard deviation (SD): 0.65) and 1.73 mm (range: 5.41–0.10 mm; SD: 1.03), respectively, while the mean angular deviation was 4.60° (range: 15.23–0.54°; SD: 2.54). The present surgical guide allows a controlled and accurate palatal miniscrew placement in three dimensions.     

Rationale for a reverse tapered body shift implant for immediate placement

Immediate implant placement holds considerable value, yet primary implant stability is often a critical factor. The aim of this study was to evaluate the stability, volumetric viability, and buccal gap size of reverse tapered body shift (RTBS) implants after immediate placement. Peak insertion torque measurements of two RTBS designs (apical 40% vs. apical 50%), relative to conventionally tapered implants, were assessed in simulated extraction sockets prepared in synthetic bone blocks. Additionally, the proximity of the RTBS implants to neighbouring teeth and anatomical structures, and the buccal gap distance were evaluated in human cadavers. The mean (± standard deviation) insertion torque was 12.00 ± 1.40 N•cm for the conventionally tapered implants (n = 50), 35.36 ± 2.74 N•cm (n = 50) for RTBS-1, and 48.20 ± 2.90 N•cm (n = 50) for RTBS-2; the difference between designs was statistically significant (P < 0.01). In total, 40 RTBS implants (20 per design) were placed in six cadaveric premaxillae. Only one locus was inappropriate for both RTBS implant designs, due to the proximity of neighbouring teeth. The average buccal gap for both implant designs was 2.8 mm (P = 0.104). The improved primary stability and increased buccal gap size with RTBS implants may enhance the feasibility of immediate placement. The study findings should be further validated in clinical trials.