Maxillary Segment Research Articles

Photoelastic models applied to dental restorations

To improve the understanding of the changes generated by restorative procedures through photoelastic models. Dental reconstruction should be based on principles of occlusion in order not to cause premature contact points during preparation and restoration procedures that can lead to disorders such as occlusal trauma, temporo-mandibullary joint dysfunction, or fractures. This paper presents a didactic method to objectively visualize occlusal loads and their distribution. Photoelastic models of teeth and maxillary segments were made to visualize the effects of dental preparations and restorations, as well as the wear of premature contact points. The direction, intensity and distribution of stresses in the crown and bone support were analyzed by photoelasticity. The technique allows visualization of how the structures are affected from the cavity preparation, the different stresses with diamond or carbide burs, in addition to observing how a premature contact point not only affects the organ that contains it but also the surrounding structures.

46 - Optimal Intrusive Force for a Periodontally Compromised Tooth: A Finite Element Analysis Strategy

The present study evaluated the optimal force for orthodontic intrusive mechanics of a tooth with different levels of periodontal support reduction using a finite element analysis (FEA) approach. An anatomical 3D model was constructed representing a second unirradicular premolar inserted into a maxillary bone segment. Based on the control model, three horizontal bone resorption conditions were simulated with alveolar bone height loss of 2 mm, 4 mm, and 6 mm (R2, R4, and R6, respectively). An 25 cN intrusive force was used for the two simulated mechanics: bilateral mini-implant intrusion and conventional intrusion. A root resorption risk index (RRRi) was calculated by dividing the maximum compressive hydrostatic stress in the periodontal ligament by the hydrostatic stress of the capillaries (4.7 kPa). It was assumed that the optimal intrusive force of reduced periodontal premolars was reached when the compressive hydrostatic stress distributions pattern of the reduced models was similar to those found in the control models of the corresponding mechanics. The FEA optimal force values for each model were compared with those obtained by the analytical formula (Force = stress x area). A linear trendline was observed between the control force reduction percentage and the bone loss height for both mechanics. For each millimeter of bone height loss, the control force had to be reduced by 9% for conventional intrusion, and by 8% for bilateral mini-implant intrusion. The root resorption risk index and the optimal intrusive force depends not only on the remaining root area with ligament support, but also on the intrusive mechanics used. The use of bilateral mini-implants in orthodontic intrusion reduced the external apical root resorption risk index and increased the optimal intrusive force. The proposed FEA strategy provided an easy, precise and feasible approach to suggest the optimum force in a clinical situation.

Modified Cupar's method for immediate diastema closure

Anterior maxillary osteotomy or ostectomy (AMO) is a safe, reliable, and easily adaptable procedure routinely performed in orthognathic surgery for the management of the dentoalveolar segment of the anterior maxilla. The anterior segmental maxillary osteotomy was first performed in 1921 by Cohn-Stock. Several modifications were done regarding approaches for AMO; however, Cupar's method is the most preferred approach by the surgeons and in practice since several decades. A novel midline split osteotomy is performed in combination with Cupar's method for superior and posterior repositioning of anterior maxillary segment in combination with immediate closure of diastema in this case report.

Orthognathic Surgery's Effects on Subjects with Cleft Lips' Speech and Breathing

Cleft lip frequently vitrine intense dent facial abnormalities that demand orthognathic surgical operation. Orthognathic surgical operation in those fatalities generally consists of now no longer closest maxillary Cleft development, however in addition sagittal, horizontal, and vertical motion of each jaws. Exact making strategies and implementation bids many complications, due to the occurrence of prodigious blemish tissues as of former operations, tissue deficits, the unruly of positioning a sections of jaw and tender muscles. Other challenging conditions in cleft victims are nuisances associated with post-surgical air route, dialog, velopharyngeal failure, nerve harm, and impurities. This appraisal is embattled on orthognathic surgical procedure in cleft lip patients, administration, practices, accomplishment, and pains. Cleft lip befalls when one or both median adenoidal progressions bomb to wrath through the agreeing maxillary progression. The strictness of lifting diverges as of an unimportant indentation in the higher lip to a dual cleft encompassing the anterior naris in collaboration The nasal septum diverges sideways from the non-cleft in an autonomous cleft lip. The muscles on the median cross of the cleft (transverse muscles of the nose and orbicularis oris) are not introduced into any of the muscles on the contralateral lateral or the skins from place to place the adenoidal septum because of this. Nasolabial (transverse nasalis, levatorlabiisuperioris, and levator labiisuperiorisalaequenasi), bila- bial (orbicularis oris), and labiomental (depressor angulioris) are the three functional groupings of superficial facial muscles that are all eliminated inferiorly. The underdevelopment of the incisor-bearing region of the maxilla is also significant. These abnormalities, by chance, inspire the mucocutaneous muscles, resulting in dislodgment of the anterior naris casing from the upper portion of the lip, disavowal of the labial skin, and anomalies of the easy skins on the opposite side of the mucocutaneous intersection.

Ortopedia prequirúrgica en pacientes con fisura labio palatina: alimentación, estética y brecha entre segmentos maxilares Revisión sistemática

Objective: To describe the results of the use of presurgical orthopedic teatments NAM, Dynacleft and nasal component in terms of esthetics, feeding, and the gap between maxillary segments. Method: We conducted a literature review in Pubmed and SCIELO, in addition to a manual search of books and scientific articles. After applying the inclusion and exclusion criteria, 25 studies were analyzed.  Results: The literature indicates that NAM and Dynacleft improve esthetics and reduce the gap between the maxillary segments. However, more evidence is needed in relation to feeding.  Conclusion: The results of presurgical orthopedics are better if treatment begins in the first days after birth. The esthetic benefits include lip and nasal symmetry, nasal tip projection, and post primary surgical scar.

Role of orthodontist in cleft lip and palate

Cleft lip and palate is one of the most common congenital anomalies occurring round the world varying with the race, ethnicity and geography. Cleft lip and/or palate problems tends to worsen as the individual grows older. Although it occurs as a different entity in itself but its presence can hamper aesthetics as well as functions by effecting growth, dentition, speech, hearing and overall appearance resulting in social and psychological problems for the child as well as the parents. Cleft lip and palate is of a multifactorial origin such as inheritance, teratogenic drugs, and nutritional deficiencies and can also occur as syndromic or non-syndromic cleft. Treatment of Cleft Lip and Palate comprises of different specialists having an individual insight in a particular case ultimately reaching to a consensus for a successful culmination of the treatment. Although appropriate timing and method of each intervention is still arguable. An orthodontist plays a role in pre surgical maxillary orthopaedics, in aligning the maxillary segments and dentition, in preparation for secondary alveolar bone grafting and finally in obtaining ideal dental relation and preparing the dentition for prosthetic rehabilitation or orthognathic surgery if required. Therefore, for efficient treatment outcome and refinement of individual techniques or variations of the treatment protocol a highly able team of specialists from different specialities is a must, preferably on a multicentre basis.

Blood Supply of Cranial Nerves Passing Through the Cavernous Sinus: An Anatomical Study and Its Implications for Microsurgical and Endoscopic Cavernous Sinus Surgery.

BackgroundDespite improvements in surgical techniques, cranial nerve (CN) deficits remain the most frequent cause of disability following cavernous sinus (CS) surgery. The most common tumor affecting the CS is meningioma. They originate from lateral wall and have their blood supply from meningohypophyseal trunk (MHT) and inferolateral trunk (ILT). Pituitary adenomas commonly invade the CS through its medial wall and receive blood supply form medial branches of the internal carotid artery (ICA) (superior and inferior hypophyseal arteries). Some tumors may grow within the CS (e.g. trigeminal schwannomas, hemangiomas). These tumors are fed by all the intracavernous ICA branches. Tumors involving the CS may also displace the neurovascular structures, therefore, a better understanding of intracavernous neurovascular anatomy may reduce the postoperative morbidity associated with approaching CS tumors. In this anatomical study, the anatomic variations and their clinical implications of the intracavernous CNs’ blood supply were evaluated through transcranial and endonasal routes.MethodsTwenty sides of ten adult cadaveric formalin-fixed, latex-injected specimens were dissected in stepwise fashion under microscopic and endoscopic magnification. The origin and course of the intracavernous ICA branches supplying the intracavernous CNs are studied.ResultsThe proximal segment of the oculomotor nerve receives blood supply from the ILT in 85%, and the tentorial artery of the MHT in 15% of specimens. The distal segment is exclusively supplied by the ILT. The proximal trochlear nerve receives blood supply from the ILT (75%) and the tentorial artery (25%); the distal segment is exclusively supplied by the superior orbital branch. The proximal third of the abducens nerve receives its vascularity exclusively from the dorsal meningeal artery, and its middle and distal thirds from the ILT. The ophthalmic and proximal maxillary segments of the trigeminal nerve also receive blood supply from the ILT. The distal maxillary segment is supplied by the artery of the foramen rotundum. All ILT branches terminate on the inferomedial aspects of the intra-cavernous CNs. Extensive anastomoses are found between ILT branches and the branches arising from external carotid artery.ConclusionUnderstanding the anatomy of the intracavernous ICA’s branches is important to improving surgical outcomes with tumors involving the CS.

Evaluation and Comparison of Stress Patterns and Teeth Displacement with Intrusion of Maxillary Posterior Segment by Skeletal Anchorage System (Infrazygomatic Crestal Bone Screw) and High Pull Headgear: A 3D Finite Element Study

Introduction: In the last decades the application of the Finite Element Methodology (FEM) has become popular. It can calculate stresses and displacement in complex structures and can anticipate the tissue responses to orthodontic mechanics applied for treating different malocclusions. This study evaluated and compared the stress patterns and teeth displacement with application of 450g of intrusive force bilaterally on maxillary posterior segment utilizing a conventional old method, High-Pull Headgear (HPHG) and a newer method, Infrazygomatic Crestal Bone Screw (IZC-BS) using 3D-FEM. Method: A 3D-FEM model of the craniomaxillary segment with maxillary teeth was reconstructed from the Cone Beam Computed Tomographic image of a patient with class II div I malocclusion on class II skeletal base with anterior open bite and 450g of intrusive force was applied bilaterally on maxillary posterior segment utilizing HPHG and IZC-BS and stress patterns and teeth displacement were studied and compared. Result: Von Mises stresses on Zygomaticomaxillary, Zygomaticotemporal and Pterygomaxillary sutures and surface landmarks on maxillary, zygomatic, temporal and sphenoid bones were more pronounced and generalized for HPHG group. Intrusion, expansion and sagittal displacement of maxillary posterior segment were also more pronounced with HPHG group. Stresses weren’t present at the apical root areas of the maxillary posterior teeth for both the groups. Conclusion: On applying equal amount of intrusive force bilaterally to the maxillary posterior segment, stress patterns and teeth displacement were more pronounced and effective for HPHG group however; apical root areas of the maxillary posterior teeth in both the groups didn’t show any stresses.

Does Maxillary Expansion for Alveolar Cleft Bone Grafting Affect Nasal Width More on the Cleft Side?

PurposeMaxillary expansion is often required in patients with cleft lip and alveolus/palate prior to alveolar cleft bone grafting (ABG) to align maxillary segments and provide space for closure of an oronasal fistula (ONF). There is limited information on how maxillary expansion affects the nasal skeleton in patients with unilateral cleft lip and alveolus/palate (UCLA/P). The purpose of this study was to compare changes in width between the cleft and non-cleft sides after maxillary expansion at the widest part of the nasal pyriform and at the level of the inferior turbinates. Patients and methodsThis is a retrospective case series of patients with UCLA/P who had maxillary expansion prior to alveolar bone grafting by the author (BLP) at Boston Children's Hospital from 2015 through 2020. Patients were included if they had maxillary expansion prior to ABG and had CBCT before and after expansion. Linear measurements at the widest aspect of the nasal pyriform and the most superior position of the inferior turbinate were recorded for both the cleft and non-cleft sides. Patients were excluded if they did not have maxillary expansion, if the CBCT data did not include all relevant landmarks, or the scans were greater than 4 years apart. Twenty patients with UCLP who underwent ABG without expansion during the same time period were used as a control group. A paired sample T-test was used to compare the cleft vs. the non-cleft side in the expansion group. The same test was used to compare the non-expanded control group to those who underwent maxillary expansion. ResultsA total of 119 patients with UCLA/P had maxillary expansion prior to ABG, but only 41 (61.0% male, mean age at ABG 10.1 years) had adequate pre- and post-expansion CBCT and were included in the study. Patients with UCLA/P who underwent maxillary expansion showed greater increase in width at the nasal pyriform and inferior turbinate levels on the cleft side compared to the non-cleft side (P < .001). When compared to the non-expanded control group of patients with UCLA/P, the percent increase at the nasal pyriform and inferior turbinate on both the cleft and non-cleft sides were statistically greater for those who underwent maxillary expansion (P < .001, P = .01 at inferior turbinate on the non-cleft side). ConclusionPatients with UCLA/P who undergo maxillary expansion prior to alveolar bone grafting have greater dimensional change of the anterior nasal skeleton on the side of the cleft.

Conformity of Virtual Surgical Plans to Postoperative Results in Segmental Orthognathic Surgery

Background/purposeVirtual surgical planning (VSP) in orthognathic surgery has enabled reconstructive surgeons to achieve more predictive results when compared to conventional methods. Still, few studies have evaluated the accuracy of VSP in more complex cases, such as those requiring maxillary segmentation. The aim of this study was to examine the conformity of virtual surgical plans to postoperative results following segmental procedures performed by a single surgeon. MethodsThis was a retrospective study of patients who had undergone triple jaw (segmental Le Fort I, bilateral sagittal split osteotomy, and genioplasty by the senior author (DMS) between 2016 and 2020. The preoperative virtual surgical plan and postoperative cone beam computed tomographic scan were registered in 3-Matic software (Materialise, Leuven, Belgium) using cranial base landmarks. The conformity of the postoperative skull model to the virtual surgical plan was quantified using linear and angular measurements at various 3D bony landmarks. The average mean difference (AMD) in the x-, y-, and z-axes was calculated. Paired T-tests were used to compare postoperative measurements with those from the pre-operative STL. Multivariate linear regression was performed to analyze and modifying effects of age, gender, number of segments (2 vs. 3), and malocclusion class. ResultsTwenty-nine patients were included (mean age 24.5 years; 72.4% female). Three-dimensional analysis showed significant AMD between the virtual plan and postop CBCT for the following landmarks: U1 Midpoint (y, AMD: 1.65mm, P = .03), B point (y, AMD: 1.63mm, P = .005), pogonion (y, AMD: 2.38mm, P = .0005), menton (y, AMD: 2.22mm, P = .0003). There were no differences between the virtual plans and postop CBCT at any other points. Transversely, the overall AMD was 1.15mm, with under-expansion occurring in 79.3% (2.18mm) and over-expansion in 20.7% of patients (1.65mm). Angular measurements revealed statistical significance for SNB (AMD: 1.38, P = .02), but not for SNA and ANB values. Multivariate regression showed no association between age, gender, segmentation (2 vs. 3), or class of malocclusion and the extent of conformity for any measurements. ConclusionThere is a high degree of conformity between the VSP and postoperative results following triple jaw orthognathic surgery with segmental maxillary osteotomies. The greatest nonconformity was found in the sagittal plane and was mostly limited to the mandible. Segmentation did not affect surgical accuracy of the maxillary movements.

Mapping of Segmental and Partial Segmental Infantile Hemangiomas of the Face and Scalp

Recognizing segmental infantile hemangioma (IH) patterns is important for risk stratification and provides clues to pathogenesis. Previously, segmental hemangiomas were mapped to 4 facial regions, 3 corresponding to known facial metameres. To refine existing maps of facial segmental IHs, examine so-called indeterminate hemangiomas as they relate to known segmental patterns, and define a novel pattern of segmental scalp hemangiomas. This retrospective cohort study was conducted at 4 pediatric dermatology centers (University of California, San Francisco; Indiana University; Medical College of Wisconsin; and Northwestern University/Ann & Robert H. Lurie Children's Hospital of Chicago) using photographic archives of patients younger than 12 years with segmental and indeterminate hemangiomas on the face and scalp. Clinical images were used to map hemangioma distribution onto standardized facial templates. Heat map densiometry identified recurrent patterns that were compared with previously published patterns of facial segmental hemangiomas. Patterns of indeterminate hemangiomas were compared with those of segmental hemangiomas. Data collection took place in 2017, and analysis took place from 2017 to 2019. Distribution and patterning of segmental and indeterminate IHs of the face and scalp. A total of 549 IHs were mapped. The borders of the frontotemporal (S1) and frontonasal (S4) segments agreed with previous segmental maps; however, the maxillary (S2) and mandibular (S3) segment borders differed with respect to the preauricular skin. In contrast with previous reports, preauricular skin segregated with the mandibular (S3) rather than the maxillary (S2) segment. Indeterminate hemangiomas occurred within and respected the same borders as segmental hemangiomas. Hemangiomas on the lateral scalp commonly occurred in a C shape extending from the posterior auricular region. This cohort study provides an updated map of facial segmental IHs with redefined maxillary (S2) and mandibular (S3) segment borders. It provides evidence that indeterminate hemangiomas are partial segmental hemangiomas respecting anatomic boundaries of their larger segmental counterparts. A newly recognized C-shaped pattern of segmental scalp hemangioma is reported.

English

Asymmetries can be considered as a huge challenge for an orthodontist because of the complex mechanics and uncertainty in stability of treatment outcomes. Multifactorial nature of the asymmetry due to wide range has complicated the classification and determination of the cases. The aetiology can be classified as hereditary and environmental factors. The occlusal cant in patients can be evaluated by frontal photographs, lateral cephalograms, clinical assessment and a threedimensional imaging methods. Photographs can be used as one of the methods to evaluate the asymmetries of the soft tissue and also the cant of lips. In recent times with the aid of computers and different software’s like power point or keynote the use of reference lines with the software, facilitates in the analysis of the smile and the occlusal plane. The management of occlusal cant includes different treatment alternatives like orthognathic surgery, orthodontic therapy, or a combination treatment of both orthognathic surgery and orthodontic therapy. The surgical approach depends upon the awareness of the patient with the severity of cant and aesthetic problems as well as the jaw discrepancy in both vertical and sagittal directions. Orthognathic surgery creates an overall skeletal as well as soft tissue improvement including the lips. In cases with OC in anterior segment and deep - bite malocclusion a combination treatment is required. To reduce the anterior vertical height and to achieve more stable results intrusion of molars is considered using skeletal anchorage. The skeletal anchorage (miniscrews or miniplates) can be used for the correction of the cant in maxillary segment and the surgical treatment for correction of the asymmetry of the face like sagittal split osteotomy, ramus osteotomy etc. can be carried out. To achieve satisfactory outcome the clinician must examine and find the etiological factors and proper treatment planning has to be carried out based on the type of occlusal cant such that the outcome shows aesthetic smile along with good facial symmetry. KEY WORDS Occlusal Cant, Facial Asymmetry, Skeletal Asymmetry, Cant.

Root resorption associated with maxillary buccal segment intrusion using variable force magnitudes.

To compare the root resorption resulting from miniscrew-supported maxillary posterior dentoalveolar intrusion using two different force magnitudes. Adult patients with skeletal open bite, indicated for maxillary posterior dentoalveolar intrusion, were recruited and randomly assigned to the comparison or intervention groups. The comparison group involved applying 200 g of intrusive force per segment, which measured 20 g per root, while this force was 400 g per segment in the intervention group, measuring 40 g per root. Twenty participants were included in the final analysis after 2 patients dropped out, 1 in each group, to end up with 10 subjects (200 roots) per group. There was statistically significant root resorption of 0.84 ± 0.96 mm and 0.93 ± 1.00 mm in the comparison and the intervention groups, respectively. However, there was no statistically significant difference between the groups. Root resorption inevitably took place in association with orthodontic intrusion. However, increasing the magnitude of the intrusive force did not increase the amount of root resorption, either statistically or clinically.

A Cross-Sectional Study of Labial Bone and Covering Soft Tissue in Maxillary Anterior Segment: A Dilemma in Orthodontics.

Purposes The thickness of the buccal bone and its covering gingiva is pivotal in determining the prognosis of implant therapy as well as fixed orthodontic appliances, especially nonextraction treatments. The purpose of this study was to evaluate the buccal bone thickness and covering soft tissue in the maxillary anterior segment. Methods This study measured the hard tissue thickness at 2 and 5 mm more apical from the crest and at the root apical apex, as well as the distance from the CEJ to the alveolar crest, using 80 CBCT images divided into three age groups. In addition, the distance from free gingiva to alveolar crest and from free gingiva to CEJ was measured. The acquired data then was analyzed using an ANOVA, t-test, and Pearson correlation to investigate any associations or statistically significant differences between parameters. Results The highest mean soft tissue thickness at the 5 mm level was for central incisors and the least for canine. The highest mean thickness of soft tissue at the crest level and its 2 mm apical level was related to central incisors and the lowest mean thickness at these levels was related to canine. Analysis of hard tissue variables showed the lower thickness of hard tissue at higher ages compared to the young patients group, but the thickness of the soft tissue increases with age. Conclusion The highest mean thickness of the buccal hard tissue in the maxillary anterior segment was in lateral and central incisors. Also, the most prominent thickness of the labial soft tissue was in the central and lateral incisors at levels close to the crest.

Final Posttreatment Occlusion in Patients With Unilateral Cleft Lip and Palate.

Objective:To evaluate final posttreatment occlusion in patients with complete unilateral cleft lip and palate (cUCLP) by comparing (1) 3 treatment centers, (2) males and females, (3) cleft and noncleft sides, (4) right- and left-sided clefts, and (5) orthodontic treatment with/without orthognathic surgery (OS).Design:Retrospective cohort study.Patients:Blinded posttreatment dental casts of 56 patients (19.4 ± 1.4 years) with cUCLP from 3 centers in Switzerland.Main Outcome Measure:Occlusal assessment using the modified Huddart/Bodenham (MHB) index.Results:Our sample comprised 35 males and 21 females, 46 with left- and 10 with right-sided clefts, of which 32 had undergone OS. The final posttreatment occlusion showed a median MHB score of 0 (interquartile range: −1.0 to 2.0) in the total sample and did not seem to depend on treatment center, sex, or OS. The MHB scores for the anterior buccal and the buccal segments were more negative on the cleft than on the noncleft side (P = .002 and P = .006, respectively). When the cleft was on the left side, the MHB score tended to be more positive in the labial (P = .046) and anterior buccal segments (P = .034).Conclusions:This study shows a very satisfactory final posttreatment occlusion in patients with cUCLP. The more constricted buccal occlusion on the cleft side emphasizes the attention that should be given in correcting the more medially positioned lesser maxillary segment. The influence of cleft-sidedness should be analyzed further on a sample including more patients with right-sided clefts.

Polyphosphate (PolyP) for alveolar cleft repair: study protocol for a pilot randomized controlled trial

ObjectiveBone grafting is an important surgical procedure to restore missing bone in patients with alveolar cleft lip/palate, aiming to stabilize either sides of the maxillary segments by inducing new bone formation, and in bilateral cleft cases also to stabilize the pre-maxilla. Polyphosphate (PolyP), a physiological polymer composed of orthophosphate units linked together with high-energy phosphate bonds, is a naturally existing compound in platelets which, when complexed with calcium as Ca-polyP microparticles (Ca-polyP MPs), was proven to have osteoinductive properties in preclinical studies.AimTo evaluate the feasibility, safety, and osteoinductivity of Ca-polyP MPs as a bone-inducing graft material in humans.MethodsThis prospective non-blinded first-in-man clinical pilot study shall consist of 8 alveolar cleft patients of 13 years or older to evaluate the feasibility and safety of Ca-PolyP MPs as a bone-inducing graft material. Patients will receive Ca-polyP graft material only or Ca-polyP in combination with biphasic calcium phosphate (BCP) as a bone substitute carrier. During the trial, the participants will be investigated closely for safety parameters using radiographic imaging, regular blood tests, and physical examinations. After 6 months, a hollow drill will be used to prepare the implantation site to obtain a biopsy. The radiographic imaging will be used for clinical evaluation; the biopsy will be processed for histological/histomorphometric evaluation of bone formation.DiscussionThis is the first-in-man study evaluating the safety and feasibility of the polyP as well as the potential regenerative capacity of polyP using an alveolar cleft model.Trial registrationIndonesian Trial Registry INA-EW74C1N. Registered on 12 June 2020

Robot-Assisted Maxillary Positioning in Orthognathic Surgery: A Feasibility and Accuracy Evaluation.

Several methods enabling independent repositioning of the maxilla have been introduced to reduce intraoperative errors inherent in the intermediate splint. However, the accuracy is still to be improved and a different approach without time-consuming laboratory process is needed, which can allow perioperative modification of unoptimized maxillary position. The purpose of this study is to assess the feasibility and accuracy of a robot arm combined with intraoperative image-guided navigation in orthognathic surgery. The experiments were performed on 12 full skull phantom models. After Le Fort I osteotomy, the maxillary segment was repositioned to a different target position using a robot arm and image-guided navigation and stabilized. Using the navigation and the postoperative computed tomography (CT) images, the achieved maxillary position was compared with the planned position. Although the maxilla showed mild displacement during the fixation, the mean absolute deviations from the target position were 0.16 mm, 0.18 mm, and 0.20 mm in medio-lateral, antero-posterior, and supero-inferior directions, respectively, in the intraoperative navigation. Compared with the target position using postoperative CT, the achieved maxillary position had a mean absolute deviation of less than 0.5 mm for all dimensions and the mean root mean square deviation was 0.79 mm. The results of this study suggest that the robot arm combined with the intraoperative image-guided navigation may have great potential for surgical plan transfer with the accurate repositioning of the maxilla in the orthognathic surgery.

Management of trauma to the anterior segment of the maxilla: alveolar fracture and primary incisors crown and root fracture

Background: An injury to both the primary and permanent teeth and the supporting structures is one of the most common dental problems seen in children. Splinting is usually difficult or impossible to perform in the primary dentition (due to diminutive room size and lack of patient cooperation). Healing must, therefore, occur despite mobility at the fracture line, usually resulting in interposition of connective tissue. In some instances, infection will occur in the coronal pulp. The present study reported a case of trauma to the anterior primary teeth and alveolar bone in a four year old child. The trauma has caused fracture to the crowns and roots of the primary anterior teeth. The following case was managed in a procedure that may provide primary teeth subjected to trauma a better chance than extraction with a better prognosis. Case presentation: a 4 and a half year old child was subjected to trauma in anterior segment of maxilla. Suturing of the torn soft tissue was the first step followed by pulpotomy for the left primary lateral incisor. Fixation of the right primary central and lateral incisors was done by acid etch wire fixation. Both clinical and radiographic follow up was carried out for 6.4 years. Results: healing of the soft tissue was observed after one week and completed after two months. Fixation of the teeth continued for ten months. The fracture lines in the roots remained in position. Clinically there was no sign of any pulpal inflammation or necrosis. Radiographically, no signs of infection to the surrounding tissues could be seen, no resorption in the alveolar bone, external or internal resorption of the root did not happen also. After ten months fixation ended and the wire was removed. At that time there was normal resorption of the roots of the primary incisors in relation with the normal development of the permanent incisors. After 3 years both permanent central incisors erupted in their normal position. After 6.4 years all four permanent incisors erupted into occlusion in their normal position. Conclusion: primary teeth with root fractures and severely mobile coronal fragments can be treated by a conservative approach. The severity of the sequels is directly related to the degree of permanent tooth formation (child’s age), type of dental trauma and extent of the impact.

Maxillary repositioning using a CAD/CAM wafer and an intraoperative navigation system for bimaxillary orthognathic surgery using segmental Le Fort I osteotomy: A pilot study

ObjectiveThe precision of maxillary repositioning using computer-aided design/computer-aided manufacturing (CAD/CAM)-generated wafers and a surgical navigation system for bimaxillary orthognathic surgery (BMOS) using segmental Le Fort I osteotomy was evaluated. MethodsSix participants with jaw deformities who required BMOS incorporating segmental Le Fort I osteotomy were included. The preoperative simulation was performed using a three-dimensional skull model on the simulation software, and a wafer for maxillary repositioning was prepared by CAD/CAM. Using the CAD/CAM-generated wafer and intraoperative navigation system, the maxillary segments were repositioned to agree with virtual surgical planning. The ideal movements of the preoperative simulation were compared with the actual movements after the surgery, and the errors of the ideal movements with reference to the actual movements were evaluated three-dimensionally at seven evaluation points. ResultsThe largest and smallest median errors calculated from the differences between the ideal and actual 3-D movements were, respectively, 0.65 mm at anterior nasal spine, 0.02 mm at posterior nasal spine. There is no significant difference was observed between ideal and actual movements in either 2-D and 3-D. ConclusionThe clinical accuracy of maxillary repositioning with the CAD/CAM wafer and an intraoperative navigation system in segmental Le Fort I osteotomy was revealed in the present study.

A novel CAD/CAM composite occlusal splint for intraoperative verification in single-splint two-jaw orthognathic surgery

BackgroundPrevious computer-generated splints were designed and produced without modification than the traditional occlusal splints, which did not facilitate surgeon's intraoperative judgment in the single-splint two-jaw orthognathic surgery. Modifications of the digital occlusal splint can be achieved using computer-aided design and computer-aided manufacturing (CAD/CAM) software. This study reported the design, clinical application and validation of a novel CAD/CAM occlusal splint. MethodsThe maxillary and mandibular segments were fixed into the final occlusal splint and moved to the planned position according to the 3-dimensional simulation. The composite occlusal splint has 4 orthogonal bars to facilitate intraoperative assessment of the dental and skeletal midline, facial soft tissue midline, occlusal plane, upper tooth show, facial symmetry and facial bone position. To validate the surgical outcome, 5 parameters including pitch, roll and yaw rotations, midline deviation and chin position were measured on the virtual plan and the postoperative cone-beam computed tomography images to quantify the difference. ResultsThe results showed no significant differences in the 5 parameters between the simulation and postoperative images. The root-mean-square difference between the conventional splints and CAD/CAM surgical splint ranged from 0.18 to 0.31 mm by superimposition of the two image models. All patients were satisfied with the treatment outcomes. Overall, this novel occlusal splint is ideal for verification of the maxillomandibular position during surgery. ConclusionThe novel composite occlusal splint provided useful and informative check to verify the maxillomandibular complex (MMC) position and facial appearance in single-splint two-jaw orthognathic surgery.