Abstract
The aim of this study was to evaluate the stability of Le Fort I maxillary inferior repositioning surgery in patients with a vertical maxillary deficiency at least 6 months after surgery. The electronic databases were searched to identify all articles reporting the long-term effects of one-piece maxillary inferior repositioning with rigid fixation. Methodological quality was evaluated according to 15 criteria related to study design, measurements, and statistical analysis. Two articles were identified, with a total of 22 patients. The maxilla was repositioned inferiorly from a mean 3.2 to 4.5 mm in the anterior part and from a mean 0.1 to 1.8 mm in the posterior part. At 6 months post-treatment, absolute relapse of a mean 1.6 mm was measured for the anterior part of the maxilla and 0.3 mm for the posterior part of the maxilla. The stability of maxillary inferior repositioning surgery could not be confirmed due to the small sample size, unclear diagnosis, and potential confounding factors.
The treatment of patients with a vertical maxillary deficiency is challenging because they frequently require a downward movement of the maxilla to attain a functional and aesthetically acceptable treatment result. Orthodontic treatment alone is not able to achieve these goals, and in these patients a combination of orthodontic treatment and maxillary inferior repositioning surgery is the best treatment option. However, maxillary inferior repositioning surgery has been regarded as relatively unstable, with a reported relapse in the literature ranging from 50% up to 100%. One of the approaches proposed to reduce relapse is rigid fixation of the maxillary segments.
The use of rigid internal fixation (usually titanium miniplates) in maxillary inferior repositioning surgery should ensure stability of the maxilla immediately after the operation. The long-term stability should also be improved because miniplates remain in situ for at least 6 months. Although some authors question whether miniplates alone provide adequate maxillary stability, rigid internal fixation is used routinely in maxillary inferior repositioning surgery. Therefore the aim of this study was to evaluate the stability of Le Fort I maxillary inferior repositioning surgery with rigid internal fixation in adult patients with a vertical maxillary deficiency at least 6 months after surgery, by performing a systematic review of randomized controlled trials, prospective cohort studies, and primary publications on retrospective studies.
Materials and methods
Protocol and registration
The protocol for this systematic review was registered prior to the study in the International Prospective Register of Systematic Reviews (PROSPERO, http://www.crd.york.ac.uk/PROSPERO ), registration number CRD42012002174.
Eligibility criteria
Inclusion criteria were the following: (1) randomized clinical trials, prospective cohort studies, or retrospective original studies; (2) adult patients with a maxillary vertical deficiency; (3) surgical intervention: one-piece Le Fort I maxillary inferior repositioning surgery with rigid internal fixation; (4) studies with a minimum of 10 subjects in the sample; (5) lateral cephalometric head films taken pre-surgery, post-surgery (≤7 days), and at least 6 months after surgery.
The following were excluded: (1) case reports and review/summary articles; (2) patients with craniofacial anomalies or those who were medically compromised; (3) patients in whom Le Fort I maxillary inferior repositioning surgery with wire fixation was performed; (4) patients undergoing multiple-piece Le Fort I maxillary inferior repositioning surgery.
Information sources and search
PubMed (1950s to present) and Embase (1974 to present) databases and the Cochrane Central Register of Controlled Trials (1992 to present) were searched until 11 November 2011 and subsequently updated to 24 June 2014 to identify all articles reporting the long-term effects of Le Fort I maxillary inferior repositioning surgery with rigid maxillary fixation.
The following strategy was used for the PubMed search: (“Le Fort I” [Title/Abstract] OR maxilla* [Title/Abstract] OR “Osteotomy, Le Fort” [MeSH]) AND (Osteotom* [Title/Abstract] OR surgery [Title/Abstract] OR operation [Title/Abstract]) AND (inferior repositioning OR repositioning OR inferior OR downgraft*). The search strategies for Embase and the Cochrane register were equivalent to that used in the PubMed search. The grey literature was not searched.
In addition, all references in the studies included were hand-searched for potentially relevant studies not identified in the initial literature search. Authors were not contacted for missing information. No language restriction was applied.
Study selection
Two reviewers (JC and RK) assessed eligibility independently of each other in an unblinded manner. All titles and abstracts of the studies identified initially were screened to select those reporting on the long-term stability (≥6 months) of maxillary inferior repositioning surgery with rigid maxillary fixation. Subsequently, full-text papers of the potentially relevant studies were retrieved and perused by the reviewers for eligibility. Any disagreement was resolved by consensus between the two observers. Next, a hand-search of the reference lists of the studies included was performed by the first author.
In the case of more than one publication on the same patient group for the same postoperative follow-up, the most informative and relevant article was included in this systematic review.
Data extraction
One observer extracted the following data from the selected studies: year of publication, type of study, sample size, type of malocclusion, type of surgical intervention, bone grafting if reported, number of surgeons involved, mean age at surgery, length of follow-up period, mean maxillary inferior repositioning, and relapse at follow-up ( Tables 1 and 2 ). Subsequently, the accuracy of the data was verified by the second observer. The principal summary measures were defined as differences in mean values for skeletal variables between pre-surgery and immediately post-surgery (change during surgery) and between immediately post-surgery and at least 6 months post-surgery (relapse).
| Kretschmer et al., 2010 | Perez et al., 1997 | |
|---|---|---|
| Type of study | Retrospective, consecutively treated patients | Retrospective |
| Number of patients | 12 (out of 60 patients who had Le Fort I osteotomy; segmental osteotomies excluded; gender proportion NR) | 10 (out of 28 patients who had MIR; segmental osteotomies excluded; gender proportion NR) |
| Malocclusion | NR | NR |
| Type of surgery | NR | NR |
| Bone grafting | In some patients | In some patients |
| Number of surgeons | Attending and residents (number of surgeons NR) |
‘Two surgical groups’ |
| Age at surgery | Mean 25.7 years a (range 15–47 years) | ‘At least 16 years old for women and 18 years for men’ |
| Follow-up | 1–1.3 years a | At least 0.5 years or final post-treatment orthodontic cephalometric radiographs |
a Out of 60 patients who had MIR; segmental osteotomies excluded.
| Kretschmer et al., 2010 | Perez et al., 1997 | |
|---|---|---|
| Reference system | x -axis: S–N rotated through N by 7° clockwise y -axis: perpendicular through N |
x -axis: S–N rotated through N by 7° clockwise y -axis: perpendicular through S |
| Surgical change, mean mm (SD) (T1–T2) | ||
| ANS vertical | 3.2 (2.1) | 4.5 (3.1) |
| PNS vertical | 1.8 (1.1) | 0.1 (3.4) |
| Me vertical | – | 0.1 a (3.6) |
| Post-surgical change, mean mm (SD) (T2–T3) | ||
| ANS vertical | 0.1 b (1.3) | −1.6 (1.9) |
| PNS vertical | −0.3 (0.9) | 0.3 b (2.0) |
| Me vertical | – | −0.4 a (2.7) |
Assessment of study quality
The methodological quality of the selected publications was assessed independently by two observers (JC, RK) according to the scoring system of Gordon et al. This evaluation system for the methodology of clinical trials is based on 15 criteria related to study design, measurements performed, and statistical analysis. The criteria are listed in Table 3 . The item was scored with a checkmark when a criterion was fulfilled. If a criterion was not applicable for a study, ‘n/a’ (not applicable) was marked against it. Study quality was expressed as the percentage of criteria fulfilled in relation to the total number of applicable criteria. The averaged quality (aQ) was rated as follows: aQ < 55% indicates poor quality; 55% ≤ aQ < 70% indicates moderate quality; aQ ≥ 70% indicates good quality. A low score reflects a high risk of bias, whereas a high score suggests a low risk of bias.
| I. Study design (total = 7; response: Y, N, n/a) |
| A. Objective: objective clearly formulated |
| B. Sample size: considered adequate |
| C. Sample size: estimated before collection of data |
| D. Selection criteria: clearly described |
| E. Baseline characteristics: similar baseline characteristics |
| F. Timing: prospective |
| G. Randomization: stated |
| II. Study measurements (total = 3; response: Y, N) |
| H. Measurement method: appropriate to the objective |
| I. Blind measurement: blinding |
| J. Reliability: adequate level of agreement |
| III. Statistical analysis (total = 5; response: Y, N) |
| K. Dropouts: dropouts included in data analysis |
| L. Statistical analysis: appropriate for data |
| M. Confounders: confounders included in analysis |
| N. Statistical significance level: P -value stated |
| O. Confidence intervals provided |
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