One-year postoperative stability of LeFort I osteotomies with biodegradable fixation: A retrospective analysis of skeletal relapse

Reliability of Anterior Nasal Spine as a Reference Point After LeFort I Surgery Using Three-Dimensional Analysis

ABSTRACT

To evaluate the stability of maxilla following orthognathic surgery, it is necessary to consider the positional change of various landmarks according to bone remodeling of the maxilla. This study aimed to evaluate the stability of the anterior nasal spine (ANS) as a reliable landmark after orthognathic surgery. Forty-seven patients with skeletal class III malocclusion who underwent bimaxillary orthognathic surgery were included. Skeletal changes were measured using cone-beam computerized tomography at 3 time points: preoperative (T0), 1-month postoperative (T1), and 12-month postoperative (T2). Linear changes of the 6 landmark points of the maxilla were measured in 3 directions: anteroposterior, vertical, and transverse. The data were analyzed with paired t tests, independent t tests, and multiple regression analysis. At 12-month postoperatively, the ANS showed mean (standard deviation) 1.23 (1.07) mm posterior movement (P = 0.00), while other landmarks did not show positional changes, implying bony resorption of ANS. Multiple regression test showed surgical forward movements of ANS (T1-0) affect the postoperative backward changes (β = -.05, P < 0.05). There was a negative correlation between the surgical movement and postoperative change of ANS by Pearson correlation test (r = -0.38, P < 0.05). The ANS is not a reliable measurement point in three-dimensional superimposition after orthognathic surgery. Therefore, in studying the stability and positional change pattern after LeFort I surgery, it is not recommended to use ANS as a reference point, as changes can occur in the measurement point itself.

Skeletal and Dental Stability Following Different Magnitude of Le Fort I Advancement in Patients With Cleft Lip and Palate

PURPOSE

The purpose of this study was to measure the association between the magnitude of advancement and dental and skeletal relapse in patients with cleft lip and palate (CLP).

METHODS

A single-institution retrospective cohort study of skeletally matured patients with CLP who underwent isolated Le Fort I advancement surgery between 2013 and 2019 was studied. Patients were included if they had lateral cephalograms or cone-beam computed tomography (CBCT) at preoperative (T1), immediately postoperative (T2), and 1-year follow-up (T3). Lateral cephalometric landmarks were digitized and measured. The sample was divided on the basis of the magnitude of skeletal advancement: minor (<5 mm), moderate (≥5 but <10 mm), and major (≥10 mm) advancement groups. The mean advancement and relapse were compared between groups using 1-way ANOVA. Correlation between the amount of surgical advancement and relapse was evaluated.

RESULTS

Forty-nine patients with nonsyndromic CLP with hypoplastic maxilla met inclusion criteria and the sample consisted of 36 males and 13 females with the mean age of 19.5 years. In the minor, moderate, and major advancement groups, the mean advancement at point A was +4.1 ± 0.4, + 7.5 ± 1.4, and +11.3 ± 1.3 mm, respectively. At 1-year follow-up, the mean relapse at point A was -1.3 ± 1.2, -1.1 ± 1.2, and -1.7 ± 1.5 mm, respectively. There was no significant difference in the relapse amount between all surgical groups. No correlation between the magnitude of advancement and relapse was found.

CONCLUSIONS

This study demonstrated no statistically significant difference in skeletal stability between a minor (<5 mm), moderate (≥5 but <10 mm), and major (≥10 mm) Le Fort I advancement groups in patients with clefts. Regardless of the degree of advancement, mild skeletal relapse was observed in all 3 groups.

Skeletal and Dental Correction and Stability Following LeFort I Advancement in Patients With Cleft Lip and Palate With Mild, Moderate, and Severe Maxillary Hypoplasia

OBJECTIVE

This study evaluates skeletal and dental outcomes of LeFort I advancement surgery in patients with cleft lip and palate (CLP) with varying degrees of maxillary skeletal hypoplasia.

DESIGN

Retrospective study.

METHOD

Lateral cephalograms were digitized at preoperative (T1), immediately postoperative (T2), and 1-year follow-up (T3) and compared to untreated unaffected controls. Based on the severity of cleft maxillary hypoplasia, the sample was divided into 3 groups using Wits analysis: mild: ≤0 to ≥-5 mm; moderate: <-5 to >-10 mm; and severe: ≤-10 mm.

PARTICIPANTS

Fifty-one patients with nonsyndromic CLP with hypoplastic maxilla who met inclusion criteria.

INTERVENTION

LeFort I advancement.

MAIN OUTCOME MEASURE

Skeletal and dental stability post-LeFort I surgery at a 1-year follow-up.

RESULTS

At T2, LeFort I surgery produced an average correction of maxillary hypoplasia by 6.4 ± 0.6, 8.1 ± 0.4, and 10.7 ± 0.8 mm in the mild, moderate, and severe groups, respectively. There was a mean relapse of 1 to 1.5 mm observed in all groups. At T3, no statistically significant differences were observed between the surgical groups and controls at angle Sella, Nasion, A point (SNA), A point, Nasion, B point (ANB), and overjet outcome measures.

CONCLUSIONS

LeFort I advancement produces a stable correction in mild, moderate, and severe skeletal maxillary hypoplasia. Overcorrection is recommended in all patients with CLP to compensate for the expected postsurgical skeletal relapse.

Variables associated with stability after Le Fort I osteotomy for skeletal class III malocclusion

The purpose of this study was to assess skeletal stability and predictors of relapse in patients undergoing an isolated Le Fort I osteotomy. A retrospective cohort study of 92 subjects undergoing Le Fort I osteotomy for Class III malocclusion was implemented. Predictor variables were demographic and perioperative factors. The primary outcome variable was postoperative skeletal position with relapse defined as >2mm sagittal and/or vertical change at A-point on serial lateral cephalograms at immediate postoperative, 1 year, and latest follow-up time points. Mean advancement at A-point was 6.28±2.63mm and mean lengthening was 0.92±1.76mm. Eight subjects (8.70%) had relapse (>2mm) in the sagittal plane, and two subjects (2.17%) in the vertical plane. No subjects required reoperation for relapse as overbite and overjet remained in an acceptable range due to dental compensation. In regression analysis, magnitude of maxillary advancement was an independent predictor of relapse in the sagittal plane (P=0.008). There were no significant predictors of relapse in the vertical plane. This study suggests that isolated Le Fort I osteotomy for correction of skeletal Class III malocclusion is a stable procedure and that greater advancement is an independent risk factor for sagittal relapse.

Resorbable Versus Titanium Fixation of Le Fort I Osteotomy

Resorbable and titanium systems have been used in maxillary fixation. The aim of this review was to evaluate stability and morbidity of Le Fort I osteotomy by comparing both systems. It was performed in 11 databases, and reported according to preferred reporting items for systematic reviews and meta-analysis. Randomized and nonrandomized clinical trials, and retrospective comparative studies with patients who underwent nonsegmented Le Fort I osteotomy were included. Eleven articles were selected, with a total of 262 patients treated with resorbable and 252 with titanium fixation. The meta-analysis showed that when measured at point A, horizontal stability was 0.06 mm (95% confidence interval [CI] -0.19, 0.30), vertical stability for impaction was -0.43 mm (95% CI -0.94, 0.07), and for inferior repositioning was -1.29 mm (95% CI -2.62, 0.04). Morbidity was similar in the groups. Regarding infection, resorbable presented an absolute risk (AR) = 0.032, and titanium an AR = 0.025 (P = 1.0). For soft tissue reaction, an AR = 0.120 was shown for resorbable, and an AR = 0.132 for titanium (P = 0.85). Removal of fixation showed an AR = 0.024 for resorbable, and an AR = 0.025 for titanium (P = 1.0). Based on these results, resorbable and metal fixation systems seem to be equivalent with respect to stability and morbidity. This review was limited by the quality of the studies. Future studies should address these quality limitations to improve comparison between these 2 fixation approaches.

Experience with Anterior Maxillary Osteotomy Techniques: A Prospective Study of 20 Cases

Aim

This prospective study aimed at studying the complications associated with different techniques of anterior segmental maxillary osteotomy.

Material and Method

The study was conducted on 20 cases diagnosed with anteriorly prognathic maxilla with class 1 molar relation. The patients were followed up for a period of at least 1 year. The clinical and demographic data along with the intraoperative and postoperative complications associated with different treatment techniques were recorded.

Results

In five cases, Wassmund technique was followed with average time span of 32 min. Wunderer and Cupar technique took average time span of 23 min. Two patients presented with four non-vital teeth in a follow-up period of 1 year and one patient treated with Cupar's technique had complication of palatal tear. Only one patient reported with relapse in a follow-up period and none of the patients had any complication associated with hemorrhage, neurosensory alteration or requiring plate removal. The findings of our study recommend ASMO as treatment modality of choice in patients with bimaxillary and/or dentoalveolar protrusion with Cupar's technique providing more ease of operation.

Bone Regeneration Potential of Uncalcined and Unsintered Hydroxyapatite/Poly l-lactide Bioactive/Osteoconductive Sheet Used for Maxillofacial Reconstructive Surgery: An In Vivo Study

Uncalcined and unsintered hydroxyapatite/poly l-lactide (u-HA/PLLA) material has osteoconductive characteristics and is available for use as a maxillofacial osteosynthetic reconstruction device. However, its bone regeneration ability in the maxillofacial region has not been fully investigated. This study is the first to assess the bone regenerative potential of osteoconductive u-HA/PLLA material when it is used for repairing maxillofacial bone defects. A total of 21 Sprague-Dawley male rats were divided into three groups—the u-HA/PLLA, PLLA, or sham control groups. A critical size defect of 4 mm was created in the mandible of each rat. Then, the defect was covered with either a u-HA/PLLA or PLLA sheet on the buccal side. The rats in each group were sacrificed at 2, 4, or 8 weeks. The rats’ mandibles were sampled for histological analysis with hematoxylin and eosin staining, histomorphometry, and immunohistochemistry with Runx2 and osteocalcin (OCN) antibody. The amount of newly formed bone in the u-HA/PLLA group was significantly higher than that of the PLLA group. The expression of Runx2 and OCN in the u-HA/PLLA group was also significantly higher. These results demonstrate that the u-HA/PLLA material has excellent bone regenerative ability and confirm its applicability as a reconstructive device in maxillofacial surgery.

Impact of the Distance of Maxillary Advancement on Horizontal Relapse After Orthognathic Surgery

Background:

The maxillary horizontal relapse following Le Fort I advancement has been estimated to be 10% to 50%. This retrospective review examines the direct association between the amounts of maxillary advancement and relapse. We hypothesize that the greater the advancement, the greater the relapse amount.

Method:

Patients with class III skeletal malocclusion underwent maxillary advancement with either a Le Fort I or a Le Fort I with simultaneous mandibular setback (bimaxillary surgery) from 2008 to 2015. Patients were assessed for a history of cleft lip or cleft palate. Patients with known syndromes were excluded. Cephalometric analysis was performed to compare surgical and postsurgical changes.

Results:

Of 136 patients, 47.1% were males and 61.8% had a history of cleft. The mean surgery age was 18.9 (13.8-23) years and 53.7% underwent a bimaxillary procedure. A representative subgroup of 35 patients had preoperative, immediate postoperative, and an average of 1-year postoperative lateral cephalograms taken. The mean maxillary advancement was 6.3 mm and the horizontal relapse was 1.8 mm, indicating a 28.6% relapse. A history of cleft and amount of maxillary advancement were directly correlated, whereas bone grafting of the maxillary osteotomy sites was inversely correlated with the amount of relapse ( P < .05).

Conclusions:

Our data suggest positive correlation between amount of maxillary advancement and horizontal relapse as well as a positive correlation between history of cleft and horizontal relapse. Bone grafting of the maxillary osteotomy sites has a protective effect on the relapse.

Biomechanical Loading Evaluation of Unsintered Hydroxyapatite/poly-l-lactide Plate System in Bilateral Sagittal Split Ramus Osteotomy

OSTEOTRANS MX^® (Takiron Co., Ltd., Osaka, Japan) is a bioactive resorbable maxillofacial osteosynthetic material composed of an unsintered hydroxyapatite/poly-l-lactide composite, and its effective osteoconductive capacity has been previously documented. However, the mechanical strength of this plate system is unclear. Thus, the aim of this in vitro study was to assess its tensile and shear strength and evaluate the biomechanical intensity of different osteosynthesis plate designs after sagittal split ramus osteotomy by simulating masticatory forces in a clinical setting. For tensile and shear strength analyses, three mechanical strength measurement samples were prepared by fixing unsintered hydroxyapatite/poly-l-lactide composed plates to polycarbonate skeletal models. Regarding biomechanical loading evaluation, 12 mandibular replicas were used and divided into four groups for sagittal split ramus osteotomy fixation. Each sample was secured in a jig and subjected to vertical load on the first molar teeth. Regarding shear strength, the novel-shaped unsintered hydroxyapatite/poly-l-lactide plate had significantly high intensity. Upon biomechanical loading evaluation, this plate system also displayed significantly high stability in addition to bioactivity, with no observed plate fracture. Thus, we have clearly demonstrated the efficacy of this plate system using an in vitro model of bilateral sagittal split ramus osteotomy of the mandible.

Are Biodegradable Osteosyntheses Still an Option for Midface Trauma? Longitudinal Evaluation of Three Different PLA-Based Materials

The aim was to evaluate three different biodegradable polylactic acid- (PLA-) based osteosynthesis materials (OM). These OM (BioSorb, LactoSorb, and Delta) were used in 64 patients of whom 55 (85.9%) had fractures of the zygoma, five (7.8%) in the LeFort II level, two of the frontal bone (3.1%), and two of the maxillary sinus wall (3.1%). In addition to routine follow-up (FU) at 3, 6, and 12 months (m) (T1, T2, and T3) all patients were finally evaluated at a mean FU after 14.1 m for minor (e.g., nerve disturbances, swelling, and pain) and major (e.g., infections and occlusal disturbances) complications. Out of all 64 patients 38 presented with complications; of these 28 were minor (43.8%) and 10 major (15.6%) resulting in an overall rate of 59.4%. Differences in minor complications regarding sensibility disturbance at T1 and T3 were statistically significant (P = 0.04). Differences between the OM were not statistically significant. Apart from sufficient mechanical stability for clinical use of all tested OM complications mostly involved pain and swelling probably mainly related to the initial bulk reaction attributable to the drop of pH value during the degradation process. This paper includes a review of the current aspects of biodegradable OM.

Segmental stability in orthognathic surgery: hydroxyapatite/Poly-l-lactide osteoconductive composite versus titanium miniplate osteosyntheses

Hydroxyapatite was included into F-u-HA/PLLA (unsintered hydroxyapatite - Poly l-lactide) composite osteosynthesis material for its documented osteoconductive capacity. This study investigates segmental retention capacities and outcome stability using F-u-HA/PLLA composite osteosyntheses in orthognathic surgery. Of fifty patients in total, 25 patients were osteofixated with F-u-HA/PLLA osteoconductive bioabsorbable osteosyntheses and compared to a group of 25 patients treated with titanium miniplates. The F-u-HA/PLLA group included 14 maxillary advancements, 4 setbacks, 13 impactions, 5 elongations at A-point; the titanium group included 20 maxillary advancements, 2 setbacks, 11 impactions and 11 elongations. In the mandible the F-u-HA/PLLA group included 13 advancements at B-point, 11 setbacks, 16 clockwise rotations and 8 counterclockwise rotations at the Gonial angle (Ar-Go-Gn); the titanium group included 9 mandibular advancements, 5 setbacks, 8 clockwise rotations and 6 counterclockwise rotations at Ar-Go-Gn. Segmental stability and relapse were assessed comparing preoperative, postoperative and follow-up roentgen cephalometrics at 22 ± 11 months on average in F-u-HA/PLLA cases, 24 ± 22 months on average in the titanium group. All absolute operative movements were nonsignificant in the F-u-HA/PLLA cases compared to the titanium osteosynthesis cases. Relapses were nonsignificant but there was greater vertical relapse in maxillary impactions with titanium osteosyntheses. Throughout this study, F-u-HA/PLLA composite osteosyntheses appeared as stable as titanium miniplates. It can therefore be concluded, although from a limited number of patients, that the investigated osteoconductive osteosynthesis can be used in a similar way to titanium miniplates in orthognathic surgery. Compared to earlier studies using other bioabsorbable polymers in the literature, F-u-HA/PLLA proved to be more stable in segmental retention.

Comparative study of bone repair in mandibular body osteotomy between metallic and absorbable 2.0 mm internal fixation systems. Histological and histometric analysis in dogs: a pilot study

The objective of this study was to compare the bone repair along a mandibular body osteotomy stabilized with 2.0 mm absorbable and metallic systems. 12 male, adult mongrel dogs were divided into two groups (metallic and absorbable) and subjected to unilateral osteotomy between the mandibular third and fourth premolars, which was stabilized by applying two 4-hole plates. At 2 and 18 weeks, three dogs from each group were killed and the osteotomy sites were removed and divided equally into three parts: the upper part was labelled the tension third (TT), the lower part the compression third (CT), and the part between the TT and CT the intermediary third (IT). Regardless of the treatment system, union between the fragments was observed at 18 weeks and the CT showed more advanced stages of bone repair than the TT. Histometric analysis did not reveal any significant differences among the 3 parts or systems in the distance between bone fragments at 2 weeks. Although at 18 weeks the proportions of newly formed bone did not differ among TT, IT and CT, significantly enhanced bone formation was observed in all sections for the metallic group. The patterns of repair were distinct between treatments.

Segmental stability of resorbable P(L/DL)LA-TMC osteosynthesis versus titanium miniplates in orthognatic surgery

After two decades of the use of resorbable miniplates, new polymer compositions for resorbable osteosynthesis are still being developed to make the handling and outcome of operations even more predictable and give higher stability to the repositioned segments. This study investigates a new resorbable osteosynthesis system in orthognathic patients. 50 patients were treated with P(L/DL)LA-TMC resorbable osteosynthesis and compared to a group of 50 patients treated with titanium miniplates. Segmental stability and relapse were measured comparing preoperative, postoperative and follow-up lateral cephalograms. Throughout this study, resorbables appeared to be as stable as titanium miniplates except in maxillary elongation and mandibular setback. Here, the titanium miniplates showed significantly higher stability than resorbable plates. P(L/DL)LA-TMC osteosynthesis seem to have less strength against compressive forces after maxillary elongation and they are less resistant to the forces the tongue exerts, pressing against the mandible after setback. It can therefore be concluded that the resorbable osteosynthesis can be used in the same situations as titanium miniplates except in maxillary elongation and mandibular setback.