Comparison of the biomechanical behavior between commercial and 3D-printed patient-specific Ti6Al4V L-Shaped titanium plates following le fort i osteotomy using finite element analysis: A technical Note.

OBJECTIVE: To evaluate and compare the biomechanical behavior of three-dimensionally (3D) printed patient-specific Ti6Al4V with commercially made titanium mini plates following Lefort-I osteotomy using finite element analysis. METHODS: Le Fort I osteotomy was virtually simulated with a 5 mm maxillary advancement and mediolateral rotation in the coronal plane, resulting in a 3 mm gap on the left side's posterior. Two fixation methods were modeled using software to compare 3D-printed Ti6Al4V and commercial titanium mini plates, both featuring a 4-hole l-shape with thicknesses of 0.5 mm and 0.7 mm at the strategic piriform rim and zygomaticomaxillary buttress locations. Using ANSYS R19.2, finite element models were developed to assess the fixation plates and maxilla's stress, strain, and displacement responses under occlusal forces of 125, 250, and 500 N/mm². RESULTS: This comparative analysis revealed slight variation in stress, strain, and displacement between the two models under varying loading conditions. Stress analysis indicated maximum stress concentrations at the vertical change in the left posterior area between maxillary segments, with the Ti6Al4V model exhibiting slightly higher stress values (187 MPa, 375 MPa, and 750 MPa) compared to the commercial titanium model (175 MPa, 351 MPa, and 702 MPa). Strain analysis showed that the commercial titanium model recorded higher strain values at the bending area of the l-shaped miniplate. Moreover, displacement analysis revealed a maximum of 3 mm in the left posterior maxilla, with the Ti6Al4V model demonstrating slightly lower displacement values under equivalent forces. CONCLUSION: The maximum stress, strain, and segment displacement of both fixation models were predominantly concentrated in the area of the gap between the maxillary segments. Notably, both fixation models exhibited remarkably close values, which can be attributed to the similar design of the fixation plates.

Does Maxillomandibular Fixation Technique Affect Occlusion Quality in Segmental LeFort I Osteotomy?

BACKGROUND: Segmental maxillary osteotomies require precise occlusal control due to variability in individual segment positioning. The role of maxillomandibular fixation (MMF) technique on occlusal control has not been validated. PURPOSE: The purpose is to measure and compare the accuracy of occlusal positioning among MMF techniques. STUDY DESIGN, SETTING, SAMPLE: This was a double-blinded in vitro study on experiment models to simulate a 3-piece LeFort I osteotomy. The models were constricted posteriorly and expanded using 3 different MMF techniques and compared to the unaltered baseline occlusion. Based on sample size calculation, 32 separate attempts were made for each MMF technique. PREDICTOR VARIABLE: The predictor variable was MMF technique (brackets, MMF screws, and embrasure wires). MAIN OUTCOME VARIABLES: The primary outcome variable was the visual occlusal analysis score, a 1.00 to 4.00 continuous scale measuring the similarity of the achieved occlusion to the planned (control) occlusion assessed by an oral and maxillofacial surgeon and an orthodontist. High visual occlusal analysis score indicated greater occlusal accuracy, with 3.50 defined as the threshold for accuracy. The secondary outcome variable was the linear error of the achieved occlusion at the canine and first molar teeth, with lower error indicating greater accuracy. An a priori accuracy threshold of 0.5 mm was set for this variable. COVARIATES: None. ANALYSES: Kruskal-Wallis test with post hoc testing was used to analyze the difference in the outcome variables of interest. P value < .05 was considered statistically significant. RESULTS: Thirty-two attempts for each technique showed that brackets had higher VAOS than MMF screws and embrasure wires (median differences 1.49 and 0.48, P < .001), and had lower linear occlusal error (median differences 0.35 to 0.99 mm, P < .001). CONCLUSION AND RELEVANCE: MMF technique influences the quality of occlusal control, with greater visual rating scores and lower linear errors seen with brackets than with embrasure wires or MMF screws.

On the feasibility of minimally invasive Le Fort I with patient-specific implants: Proof of concept.

A novel approach to Le Fort I osteotomy is presented, integrating patient-specific implants (PSIs), osteosynthesis and cutting guides within a minimally invasive surgical framework, and the accuracy of the procedure is assessed through 3D voxel-based superimposition. The technique was applied in 5 cases. Differences between the surgical plan and final outcome were evaluated as follows: a 2-mm color scale was established to assess the anterior surfaces of the maxilla, mandible and chin, as well as the condylar surfaces. Measurements were made at 8 specific landmarks, and all of them showed a mean difference of less than 1 mm. In conclusion, the described protocol allows for minimally invasive Le Fort I osteotomy using PSIs. Besides, although the accuracy of the results may be limited by the small sample size, the findings are consistent with those reported in the literature. A prospective comparative study is needed to obtain statistically significant results and draw meaningful conclusions.

Cleft Lip and Palate: LeFort I Distraction with Halo and Hybrid Internal Maxillary Distractors.

Distraction osteogenesis is a viable treatment option for patients with a cleft associated with severe maxillary retrusion. A rigid external distraction device and a hybrid internal maxillary distractor have been used to advance the maxilla allowing for predictable and stable results. These techniques can be applied by itself or as an adjunct to traditional orthognathic procedures. The technical aspects are presented. These procedures tend to be simpler and demonstrate great stability compared to traditional surgical methods. The reasons for stability are discussed.

Cleft Lip and Palate: Le Fort I Distraction Using an Internal Device.

Maxillary hypoplasia is a commonly seen dentofacial anomaly in patients with cleft lip and palate after surgical repair of the cleft anomaly. To facilitate large horizontal movements of the maxilla, distraction osteogenesis is used to slowly stretch the soft tissue envelope with the skeletal advancement preventing tissue recoil and skeletal relapse. Internal distraction devices have the advantage of reducing the amount of physical and psychological stress placed on patients, families, and caregivers. The technique has been successful in producing stable results for large advancements of the facial skeleton when compared with conventional Le Fort I advancement and fixation of the maxilla.

Craniosynostosis: Le Fort III Distraction Osteogenesis.

The Le Fort III advancement was first described in 1950 and has since become a key technique in the armamentarium of craniofacial surgeons. The application of distraction osteogenesis to the craniofacial skeleton has allowed for large movements to be performed safely in young patients. This technique is valuable for correcting exorbitism, airway obstruction owing to midface retrusion, and class III malocclusion. It can be performed with either an external distractor or internal distractors. Although serious complications have been reported, these occur rarely when performed by experienced providers.

Orthognathic surgery: a randomized study comparing Piezosurgery and Saw techniques.

INTRODUCTION: The purpose of this study was to evaluate specific parameters: intra-operative time, facial swelling, degree of pain (VAS scale), recovery time and neurosensory disturbance in patients who underwent orthognathic surgery either using piezo or saw devices. MATERIAL AND METHODS: We designed a retrospective study, which included 100 patients who underwent bilateral sagittal split osteotomy (BSSO) surgery combined with maxillary Le Fort I. They were separated into 2 groups of 50 patients each. The surgeries were performed between September 2015 and April 2017 by the same surgeon. RESULTS: Intra-op time is unchanged but patients operated with the Piezo devices requested fewer painkilling medication and were dismissed on the second day after the surgery. Neurosensory recovery was statistically significant in the Piezo group. CONCLUSION: Far less post-op swelling and the reduction in the use of painkillers lead to a speedier recovery in patients who underwent orthognathic surgery using Piezosurgery. These patients also recovered more sensitivity in the lower lip area. KEY WORDS: Orthognatic surgery, Piezosurgery, Saw.

Orthognathic Hardware Complications in the Era of Patient-Specific Implants.

BACKGROUND: Patients undergoing orthognathic skeletal correction present with a variety of comorbidities that may affect surgical outcomes. The purpose of this study was to determine how patient risk factors and operative technique contribute to complication rates after orthognathic surgery in the era of patient-specific implants. METHODS: Retrospective cohort analysis was conducted of pediatric patients undergoing Le Fort I osteotomy, bilateral sagittal split osteotomy, and/or genioplasty from 2014 to 2018. Patient risk factors, operative characteristics, and postoperative outcomes were gathered and compared with appropriate statistics. RESULTS: Ninety-four patients met inclusion criteria, with an overall 1-year complication rate of 11.7 percent (11 of 94). Patient-specific mandibular plates are significantly associated with infection (p = 0.009; OR, 8.8), occurrence of any complication (p = 0.003; OR, 8.3), readmission (p < 0.001; OR, 11.1), and reoperation (p < 0.001; OR, 11.4). In patients with syndromes or history of cleft lip/palate, patient-specific mandibular plates are associated with infection (p = 0.006; OR, 10.3), readmission (p < 0.001; OR, 21.6), and reoperation (p < 0.001; OR, 22.9). In multivariate regression controlling for age, sex, syndrome status, and orofacial cleft history, use of patient-specific mandibular plates was associated with infection (p = 0.017; adjusted OR, 12.5), any complication (p = 0.007; adjusted OR, 11.8), readmission (p = 0.001; adjusted OR, 17.9), and reoperation (p = 0.001; adjusted OR, 18.9). CONCLUSIONS: In the era of patient-specific orthognathic surgery, syndromic status and use of patient-specific mandibular plates are associated with increased infection, readmission, and reoperation because of hardware-related complications. The authors' data support increased caution and counseling with use of patient-specific mandibular implants in patients with syndromic status, history of orofacial cleft, and history of previous maxillomandibular surgery given increased risk of hardware-related complications. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Computer-Aided Design and Manufacturing Cutting and Drilling Guides with Prebent Titanium Plates Improve Surgical Accuracy of Skeletal Class III Malocclusion.

BACKGROUND: The aim of this study was to evaluate the effects of the use of computer-aided design and manufacturing cutting and drilling guides with prebent titanium plates for the correction of skeletal class III malocclusion. METHODS: In this prospective, randomized, controlled clinical trial, 46 patients with skeletal class III malocclusion were randomly assigned into two groups. The patients underwent bimaxillary surgery with computer-aided design and manufacturing cutting and drilling guides with prebent titanium plates (experimental group) or computer-aided design and manufacturing splints (control group). Preoperative and postoperative imaging data were collected and then analyzed using Mimics Research 19.0, Geomagic Studio, and IBM SPSS Version 21.0. RESULTS: Deformity evaluation and posttreatment assessment were performed for all patients. The experimental group had fewer postoperative complications. Comparison of the linear and angular differences to facial reference planes revealed more accurate repositioning of the mandible and condyles in the experimental group, although the position of several landmarks still requires small adjustments. CONCLUSION: Computer-aided design and manufacturing cutting and drilling guides with prebent titanium plates effectively corrected skeletal class III malocclusion, providing positional control of segments with reasonable surgical accuracy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Transmucosal Pterygomaxillary Separation in the Le Fort I Osteotomy.

The Le Fort I osteotomy is a versatile operation for correction of developmental, congenital, and posttraumatic deformities of the lower midface. One of the challenges of the osteotomy is pterygomaxillary separation, with the potential for unfavorable fractures to the orbit/skull base or vascular injury. A modified technique for pterygomaxillary disjunction is the transmucosal tuberosity osteotomy. The authors have used this technique for pterygomaxillary separation in 200 consecutive Le Fort I osteotomies over a 3-year period (2014 to 2017). There were no episodes of unfavorable propagation to the skull base or orbit, oroantral or oronasal fistulae, excessive bleeding/vessel injuries, or vascular insufficiency to the maxilla. The transmucosal tuberosity approach is a reliable and safe method of performing the pterygomaxillary separation during the Le Fort I osteotomy.

Surgical Protocol for a Safe Lateral Nasal Wall Osteotomy.

PURPOSE: The purpose of this study was to define the anatomy and anatomic variations of the lateral nasal wall area to identify safe access points, determine the optimum osteotomy line for Le Fort I osteotomies, and define a surgical protocol. MATERIALS AND METHODS: The angulations and widths of 160 lateral nasal walls and the distances of the greater palatine canal were measured on axial images from coronal sections 5 mm over the deepest point of the nasal base. RESULTS: The average angle between the anterior lateral nasal wall and the medial maxillary sinus wall was 160 degrees in females and 165.67 degrees in males for the right and 155.90 degrees in females and 163.22 degrees in males for the left side. Statistically significant differences were found in the lengths, angulations, and widths of the lateral nasal walls between females and males. CONCLUSION: This study described the mean angulations and linear distances between anatomic structures of the lateral nasal wall and it defines the "Medipol protocol" for a safe osteotomy.

Patient-specific 3D printed plates improve stability of Le Fort 1 osteotomies in vitro.

PURPOSE: Selective laser melting used to manufacture patient-specific 3D-printed (PSP) plates is a delicate process, which may introduce weakened areas in the plates, with risk of fracture. This in vitro study's purpose was to test the ability of PSP plates to stabilize Le Fort I osteotomies compared with manually adapted stock plates. The study's objectives were to measure the force needed to compress the osteotomy and evaluate whether the PSP plates would break during compression. MATERIALS AND METHODS: This controlled in vitro study evaluated the maxillary stability using the clinical data from 7 patients. The virtually planned maxillary reposition was 3D-printed in 2 copies, and the osteotomy gap was fixated by either PSP plates or stock plates. The models were compressed until the Le Fort I osteotomy gap was eliminated. The primary outcome was the force needed to compress the model. The primary predictor variable was a comparison between PSP and stock plates. Secondary outcome measurements were the slope of elastic modulus, yield point, and force needed for 2 mm compression. Statistical testing was performed by Wilcoxon signed-rank test with significance level at P ≤ 0.05. RESULTS: The PSP plates performed better than stock plates in all outcome measurements. None of the plates broke during compression despite forces of more than 4000 N. The first point of failure in PSP plates was the first screw cranial to the osteotomy. In comparison, the first point of failure in stock plates was in the plates' bend at the osteotomy. CONCLUSION: In this in vitro setup, the Le Fort I osteotomies fixated with PSP plates were more stable than the osteotomies fixated with conventional stock plates. No adverse effects occurred during testing of PSP plates; thus, PSP plates seem to be a safe alternative to stock plates and may even be preferable.

The Precise Midline Positioning Instrument for Le Fort I Osteotomy.

To reduce the deviations in the horizontal direction of posterior maxilla during the maxilla Le Fort I osteotomy, the authors develop and validate the precise midline positioning instrument for Le Fort I osteotomy, which can guide the precise relocation of the truncated maxillary bone segment. The patent application for the precise midline positioning instrument for Le Fort I osteotomy is already submitted (patent no: 201711245533.6, China). The accuracy of Le Fort I osteotomy can be improved significantly, because of the amplification effect of this patent on the rotation/micro-movement of the posterior maxilla in all directions to achieve the precise movement and pairing of the maxillary bone segment. And this method is simple, efficient, and laborsaving.

Comparison between patient specific implants and conventional mini-plates in Le Fort I osteotomy with regard to infections: No differences in up to 3-year follow-up.

Individually designed osteotomies and milled or printed patient-specific osteosynthesis materials are rapidly becoming a standard in maxillofacial reconstructive surgery. The benefits of using patient-specific implants (PSIs) in orthognathic surgery are especially clear in complex cases, and for this reason they are rapidly becoming common practice. We have earlier reported the benefits related to the use of PSIs as reposition and fixation system in Le Fort I osteotomy. The aim of this study was to compare complications associated with fixation with PSIs (31 patients) versus conventional mini-plates (37 patients) in Le Fort I osteotomy. No statistically significant differences in infection, reoperations or soft tissue problems were observed between the two systems used. Interestingly, three of the 37 patients in the mini-plate group underwent reoperation due to insufficient advancement or malocclusion, whereas none of the patients in the PSI group needed reoperation. In conclusion, PSIs are reliable for use in orthognathic surgery, with no signs of infection associated complications.

Rigid External Distraction with Intranasal Bone-borne Traction Hooks for Midfacial Hypoplasia.

Rigid external distraction is currently performed to correct cases of severe maxillary hypoplasia. As an improvement of this technique, we propose the use of an intranasal bone-borne traction hook. This study is a retrospective chart review of the intranasal bone-borne traction hooks used in the treatment of severe maxillary hypoplasia. There were 110 patients treated with the hooks from 2005 to 2017. The maximum traction force was 7.75 kg, and there were few complications encountered during distraction. There were 76 patients who had the hooks removed under local anaesthesia. A cephalometric analysis was conducted in 56 patients. The average advancement of A-point was 9.9 ± 4.2 mm, 8.4 ± 2.5 mm, 11.0 ± 3.7 mm, 17.9 ± 4.4 mm for the trans-sutural distraction osteogenesis (DO), maxillary anterior segment DO, Le Fort I osteotomy DO and Le Fort III/II osteotomy DO, respectively. The average changes of sella-nasion-point A (SNA) were 8.89 ± 4.30 degrees, 8.21 ± 3.17 degrees, 10.49 ± 3.26 degrees, and 15.10 ± 4.00 degrees, respectively. The A point-nasion-B point (ANB) also showed increases in all procedures with P < 0.001. In conclusion, this technique sufficiently advances the midface and ensures the scars are concealed in the nasal base. The traction hook can bear a large traction force, causes minimal complications and is easily removed.

Segmental Multiple-Jaw Surgery without Orthodontia: Clear Aligners Alone.

Segmental Le Fort I osteotomy, a complex procedure with many mobile parts, has traditionally required presurgical orthodontics with conventional braces, composed of metal brackets, bands, and archwires. These appliances are not always accepted by patients, particularly older teenagers and professional adults who previously endured traditional orthodontia during adolescence, and now require retreatment because of jaw growth differences necessitating orthognathic surgery. Less obtrusive orthodontic therapies, involving clear aligners (e.g., Invisalign), are becoming increasingly popular, as they are less noticeable and less aesthetically objectionable. They are typically indicated for milder occlusal discrepancies, such as crowding and minor rotations, without significant vertical or transverse problems. Clear aligners in conjunction with orthognathic surgery for severe dentofacial problems are progressive and not widely used. Moreover, the most complicated of orthognathic sequences, segmental double-jaw surgery, has never before been described to be performed using Invisalign. Several potential challenges exist when performing segmental double-jaw surgery with Invisalign (i.e., no bonded or banded appliances, and no archwire). The purpose of this article is to review the feasibility of segmental double-jaw surgery without orthodontia (Invisalign only), report a series of cases, and review the technical steps involved.

Custom-Made Titanium Miniplates Associated With Ultrahigh-Molecular-Weight Polyethylene Graft in Orthognathic Surgery: An Adjunct to Maxillary Advancement.

Patients with considerable maxillomandibular anteroposterior discrepancies and maxillary hypoplasia require corrective treatment through orthognathic surgery. However, in the treatment of severe maxillary retrognathism, it is necessary to reconstruct areas of bone deficiency through grafting techniques in addition to maxillary advancement using only the Le Fort I osteotomy. Treatment in these patients is more challenging and requires high surgical predictability. Alloplastic materials often have been used for the reconstruction of poor bone contours. Ultrahigh-molecular-weight polyethylene (UHMWPE) is currently an excellent filler material for poor bone regions and is a good substitute for autografts and other alloplastic materials for its unique properties, including high biocompatibility. Insertion of this material in the fixation system customized for virtually planned orthognathic surgeries is an innovative technique. This report describes the insertion of UHMWPE into custom-made titanium miniplates manufactured by computer-aided design and computer-aided manufacturing technology for orthognathic surgery consisting of maxillary advancement and mandibular retrusion to treat a patient with Crouzon syndrome, Class III malocclusion, and severe maxillary retrognathism.

Prevalence of nasolacrimal canal obstruction and epiphora following maxillary orthognathic surgery.

Acquired injuries of the nasolacrimal apparatus may be the result of craniomaxillofacial surgical procedures, facial trauma, or inflammation. Injury to the nasolacrimal duct system following maxillary orthognathic surgery is rarely reported. This study evaluated the importance of early diagnosis and treatment of epiphora developing after Le Fort I surgery. The records of 83 patients who underwent maxillary orthognathic surgery over a 2-year period were reviewed. The prevalence of postoperative epiphora was 3.6% and it persisted for a mean of 32.7 days. No patient required further surgical treatment of the nasolacrimal duct obstruction. Clinicians should evaluate the lacrimal canal position and schedule close postoperative follow-up of injuries to the nasolacrimal apparatus. These may become permanent, necessitating additional surgery.

Internal Distraction Resulted in Improved Patient-Reported Outcomes for Midface Hypoplasia.

BACKGROUND: Both internal and external distraction devices have been used successfully in correcting midface hypoplasia. Although the indication for surgery and the osteotomy techniques may be similar, deciding when to use internal versus external devices has not been studied. The authors studied patient-reported outcomes with FACE-Q and functional surveys for internal and external devices for midface distraction patients. METHODS: Patients who underwent distraction advancement after Le Fort I and Le Fort III were surveyed using the FACE-Q survey and a functional survey. Equal groups of internal and external device patients were compared (n = 64). Data recorded included: sex, age, follow-up, diagnosis, operating room time, expected blood loss, length of stay, distraction length, consolidation time, and complications. RESULTS: Internal and external device groups were similar with regards to patient diagnosis, operative time, expected blood loss, distraction length but consolidation times differed (internal = 3.6 versus external = 1.1 months). For FACE-Q appearance appraisal, there were similarities in domain and scale. For the functional survey (airway/breathing, ocular/vision, occlusion/eating, speech/articulation), there was also similar scoring. However, internal device patients had superior FACE-Q scores for Quality of Life: Social Function (80.9 versus 68.9), Early Life Impact (92.9 versus 62.4), Dental Anxiety (70.2 versus 48.3), Psychological Well-being (87.8 versus 68.6); and Decision Satisfaction (81.2 versus 56.9) and Outcome Satisfaction (91.0 versus 84.7). CONCLUSIONS: Internal and external midface distraction patients had similar patient-reported outcomes for appearance and functional improvement; however, internal device patients were more satisfied with their quality of life and their decision to undergo the procedure.

Systematic three-dimensional analysis of wafer-based maxillary repositioning procedures in orthognathic surgery.

PURPOSE: Little is known about the three-dimensional (3D) transfer accuracy in maxillary repositioning procedures based on conventionally manufactured dental-mounted wafers. The purpose of the present study was a systematic 3D analysis for wafer-based maxillary positioning in orthognathic surgery. MATERIALS AND METHODS: A total of 92 patients underwent Le Fort I in addition to mandibular bilateral sagittal split osteotomies (BSSO). Alignment of the pre- and postsurgical CBCT data sets allowed measuring maxillary position changes in axial, sagittal and transversal directions. RESULTS: The highest achieved absolute transfer inaccuracies were 1.37 mm, ±0.84 in the sagittal direction, followed by 1.15 mm, ±0.69 in the axial, as well as 1.05 mm, ±0.79 in the transversal direction. The largest relative deviations could be found for repositions in the transversal plane (109.4%, ±4.5), followed by the axial (66.2%, ±51.5) and sagittal plane (49.3%, ±2.2). Significant transfer accuracy differences of repositioning procedures in the sagittal direction, mainly advancement procedures, could be detected if performed with (1.75 mm, ±0.90) or without (1.18 mm, ±0.78) additional rotational correction component. No significant differences were found between unidirectional and multidirectional maxillary correction procedures. CONCLUSION: The present study for the first time delivers systematic 3D accuracy data of wafer-based maxillary positioning procedures, attesting to its feasibility but also further encouraging the search for improvement strategies.