SURGICAL AND ORTHODONTIC TREATMENT METHODS IN PATIENTS WITH BIMAXILLARY PROTRUSION - A SYSTEMATIC REVIEW

Abstract

Background

The acceptable goal of treatment of bimaxillary protrusion is the retraction of maxillary and mandibular incisors with a resultant decrease in soft tissue convexity. This can be achieved by both surgical and orthodontic treatment methods. The aim of this study was to conduct a systematic literature review on the outcome of either method and other associated factors.

Methodology

Electronic databases (PubMed, Cochrane, Medline) were searched to identify studies that assessed hard and soft tissues changes in patients treated for bimaxillary protrusion with surgery or orthodontics. Abstracts that appeared to fulfill the initial selection criteria were selected, and the full-text original articles were retrieved and analyzed. Only articles that fulfilled the final selection criteria were finally considered. Their references were also hand-searched for possible missing articles from the database searches.

Results

The initial literature search identified 215 articles while 71 full text articles were retrieved for further analysis. Twenty-four publications were included in the final review. Most of the studies were retrospective with no randomized control trial. The studies showed high heterogeneity in type and technique of space closure, anchorage, orthodontic appliance and surgery. Surgical treatment was carried out for more severe cases than orthodontic treatment. Both methods achieved increased inter-incisal angle, however shorter treatment time appeared to be associated with surgery.

Conclusion

Satisfactory outcome were achieved with both treatment protocols. However, surgery was more indicated in severe cases.

Introduction

Bimaxillary protrusion is characterized by protrusive dentition and lips with reduced inter-incisal angle. It is relatively common in African /Asian populations with varying degree of severity1. The negative perception of this trait and its effects on quality of life in most cultures makes the patient to seek treatment1^-3.

The goal of treatment is retraction of maxillary and mandibular incisors with a resultant decrease in soft tissue convexity. This is achieved by extraction of premolar teeth followed by orthodontic retraction of anterior teeth using maximum anchorage mechanics4^-6, surgical treatment methods are also employed7^-9. Both methods have their advantages and disadvantages. Shorter treatment time is associated with surgical treatment however complications are often more reported with surgery when compared with orthodontic treatment method7^-9.

The aim of this study was to review the available surgical and orthodontic treatment protocols in patients with bimaxillary protrusion. The objectives were to compare the two treatment methods in terms of correction of interincial angle, rate of space closure and complications.

Methods

Literature search

This systematic review was performed between June 2017 to September 2017 in accordance with the PRISMA statement10. We searched the PubMed, Medline, Cochrane and Prospero databases using the keywords and search strings as follows: (Bimaxillary Protrusion [mesh] OR Bimaxillary proclination OR bimaxillary dentoalveolar proclination) AND ((treatment OR orthodontic treatment)). The search was restricted to human studies published in English. In addition, the ‘‘related articles’’ options in PubMed Medline and manual search of bibliographies of identified articles were used to retrieve additional studies.

Criteria for eligibility

Studies were included if they reported on: pretreatment interincisal angle, pre-treatment molar relationship, other vertical/ antero- posterior discrepancy, outcomes for patients who had been treated with surgical or orthodontic method, and followed-up of for at least 6 months. Reviews, case reports of a single case and articles that did not report pre and post treatment cephalometric analyses were excluded. The title and abstract of the identified articles were screened based on these criteria after which the full text of all eligible articles were retrieved for further analysis. References of the included articles were screened to further identify potentially eligible articles.

Quality assessment

Recognizing that more methodologically sound studies may provide more reliable conclusions, the quality of each study was assessed using a modified quality assessment checklist for observational studies11 to evaluate the methodologic soundness of each article. The list comprise four domains representing the key components of methodological quality examined as follows:

Study design

Prospective study design with a mean follow up time clearly stated as 1 year or more.

Study population

Scores were given if eligibility (Inclusion and exclusion) criteria clearly described with sufficient descriptions of baseline characteristics which include demographics and traits of bimaxillary protrusion. In addition, studies with number of cases ≥ 50 were given scores.

Interventions

Description of details of treatment technique including all relevant predictor variables.

Outcome measurements

Studies with information on all relevant outcome measures and explanation on adverse events like complications provided as well as identical interval between measurements for all patients. Studies with information on statistical analysis were similarly scored.

A score of 0 or 1 was given depending on if each item was documented or not. The maximum score is 10.

Data collection

A proforma was used to record the data from the eligible articles. Information collected included primary author, year of publication, study type, age and number of patients, follow up, and documented complications.

Statistical analysis

Descriptive statistics was used for analysis. The characteristics of the included publications were summarized and presented in tables.

Results

The initial electronic searches of databases retrieved 215 potentially eligible articles, 7 publications were identified from other sources. After initial review of the titles and abstracts, 71 articles were selected for screening, and 151 were rejected (Fig. 1). Of the 71 articles selected for further consideration, 47 were excluded because they did not meet the inclusion criteria which left 24 full-text articles for further consideration and analysis. Of the 24 included articles reviewed, all were retrospective cohort studies except one which was prospective. The study characteristics of the selected publications are reported in Table 1.

Fig. 1. Flow Chart of the Literature Selection Process.

Table 1. study characteristics.

Author/Year	Country	Study Design	Study Group/ Type	No of patients	M/F	Mean Age	Measurements Outcome(Soft tissue/dental/both)	Observation Period (months)
Yao et al/ 2008	Taiwan	retrospective	Ortho/Edgewise	47	4/43	23.5	both	24
Hosseinzadeh-Niki et al / 2016	Iran	retrospective	Ortho/fixed straight wire	18	0/18	16.4	both	24
Monga et al /2016	India	retrospective	Ortho/fixed straight wire	18	4/14	17.3	both	20
Sakthi et al/2014	India	Prospective	Ortho/surgery graft	40	20/20	21.5	both	6
Huang et al / 2015	China	retrospective	Ortho/ NR	60	15/45	23.5	both	12
Xie et al/2013	china	retrospective	Surgery	20	1/19	29.0	both	36
Solem et al /2013	USA	retrospective	Ortho/skeletal, intra oral anchorage	24	4/20	24	both	12
Felembam et al/2013	Saudi Arabia	Case series	Ortho / FA , 2stage vs enmasse retraction	2	1/1	22	both	18
Raypeyma et al/2013	Iran	retrospective	Surgery/ single jaw, bimax	40	14/26	27	both
Choo et al/2011	USA	retrospective	Surgery/ perisegmental corticotomy	24	0/24	27.3	both
Sharma/ 2010	Nepal	retrospective	ortho	30	15/15	18.4	both
Park et al/2008	Korea	retrospective	Surgery/ ant segmental osteotomy	30	1/29	36	both
Lee et al/ 2007	Korea	retrospective	Ortho/surgery	65	0/65	26	both
Bills et al/ 2005	USA	retrospective	Ortho edgewise	48	10/38	21.8	both	NR
Baek et al/2005	Korea	retrospective	Ortho/ Surgery	46	0/46	-
Tan /1996	singapore	retrospective	Ortho Edgewise	50	/	-	both	26
Diels et al/2005	USA	retrospective	Ortho/edgewise	60	30/30	14.5	both	35
Lew/ 1989	China	retrospective	Ortho/ Begg	32	/	22	both	?
O’Reilly /1989	USA	retrospective	Surg/ subapical osteotomy	14	0/14	25.5	both	6
Lew et al /1989	China	retrospective	Surg/ subapical osteotomy	19	/	23	both	19.8
Keating / 1986	UK	retrospective	Ortho/NR	30	13/17	11.8	both	61
KIm et al/ 2002	Korea	retrospective	Surgical/ corticotomy osteotomy	20	2/18	21-33	both	12
Chung et al/ 2011	Korea	Case series	Ortho/ NR	2	0/2	23-25	both	NR
Koyama et al/ 2011	Japan	retrospective	Ortho/ pm extraction, implant skeletal anchorage/ headgear	28	3/25	24.9	both

A total of 767 patients were treated for bimaxillary protrusion with either methods. The gender characteristics were reported in all the articles except for three publications with overwhelming female preponderance (137/630). Age was reported as mean and range in all but two publications ranging from 24.6-31.6 years. (Table 1).

Quality assessment: Table 2 depicts the quality assessment scores of the 24 publications. Majority of the studies were scored average suggesting that most of the studies were of moderate quality.

Orthodontic treatment method

Fourteen studies4^-6,12^-22 evaluated treatment outcome obtained with the use of orthodontic method mainly Begg, edgewise or fixed straight wire appliances. There is wide variation in the type of anchorage device (skeletal vs non-skeletal), and stage of retraction (enmasse vs 2 stage retraction) techniques.

Surgical treatment method

Seven studies23^-29 assessed outcome after surgical treatment mostly osteotomies under local anesthesia eg subapical, segmental, perisegmental, bimaxillary procedures were reported in all studies with one study reporting the additional use of bone graft30.

Both methods:

Three studies30^-32utilized a comparative study design involving both treatment protocols. The study by Baek et al³¹ indicated that better results were reported with anterior subapical osteotomies when compared with orthodontics even though the difference was not statistically significant. Similarly, Lee et al32 reported larger amount of basal bone retraction and greater change in the upper lip projection/angulation with bimaxillary anterior subapical osteotomy when compared with orthodontics with or without corticotomy. Sakthi et al30 also found faster retraction rate corresponding to higher rate of space closure and better anchorage control when surgery was carried out.

Outcome Measure:

All the studies assessed changes in both dental and soft tissues however, there is wide variation in parameters assessed with majority reporting on inter-incisal angle, upper/lower incisor retraction, upper/lower lip retraction, naso-labial angle increase, improvement in lip procumbency, treatment time, space closure and iatrogenic complications.

Discussion

The current approach to health care delivery is hinged on evidence.Clinicians prescribing one treatment method over others depend on current best evidence for rational decision making. Therefore, this present systematic review attempted to provide current evidence for which treatment method is better in treatment of bimaxillary protrusion subjects.

An earlier systematic review of orthodontic treatment demonstrated that upper and lower lips retract and nasolabial angle increases following premolar extraction in biprotrusive patients. This study however focused only on single treatment (orthodontics) in non-growing patients and as such cannot provide current comparative evidence on both treatment methods .

In this review, the level of evidence from the selected reports was moderate/low. There was no randomized clinical trial with the majority of studies being retrospective in design. The potential for bias as a result of the quality of studies analyzed should be borne in mind.

Because of the variable outcome parameters adopted for evaluating outcome measure, direct comparison of the 767 patients was not feasible. The three comparative studies provided the only opportunity for direct comparison of treatment outcome. Although, the sample size was not large enough, it is noteworthy that the better result reported in surgical protocols is devoid of major complications commonly associated with corresponding surgical procedures. Concerns about the complications of surgical treatment especially loss of tooth vitality, periodontial problems and root resorption have earlier been expressed34.

Conclusions

In conclusion, based on the available evidence, both methods achieved increased inter-incisal angle and improved convexity with satisfactory outcome. Shorter treatment time appeared to be associated with surgery. Surgery may be indicated in severe incisor proclination, adult desirous of short treatment time, and those with additional vertical and antero-postereior discrepancy eg gummy smile, basal bone prognathism cases. For better and valid comparison of result, there is need to standardize classification, treatment technique and treatment effect with more well conducted prospective studies.