|Year : 2018 | Volume
| Issue : 2 | Page : 69-74
Stability of anterior open bite correction treated with posterior teeth intrusion using temporary anchorage devices. A systematic review
Mohammed K Al-Dhubhani
Private Practice, Asser Province, KSA
|Date of Web Publication||14-Sep-2018|
Mohammed K Al-Dhubhani
Private Practice, Asser Province
Source of Support: None, Conflict of Interest: None
Anterior open bite (AOB) could be corrected by intrusion of the posterior teeth using temporary anchorage device (TAD). However, stability of such approach is still not obvious. The aim of this paper is to systematically review the available scientific evidence regarding the stability of AOB correction on treated with posterior teeth intrusion using TADs. Electronic databases and certain orthodontic journals were searched. Randomized controlled trials (RCTs), nonRCTs (nRCTs), and retrospective studies (RTSs) investigating the stability of AOB correction treated with intrusion of maxillary, mandibular posterior teeth or both using any type of TAD were retrieved. Both reviewers were involved in data extraction and analysis, and any disagreements were resolved by discussion. Three RTSs and one nRCT were recognized. Low level of scientific evidence was identified after assessment of the risk of bias of the involved studies with no related RCT was performed. Although, overbite relapsed after debonding, positive overbite is maintained in all 95 participants of the involved studies. Overbite relapse could not be explained by the relapse of posterior teeth intrusion only. Weak scientific evidence supports that correction of the AOB by posterior teeth intrusion using TAD is stable approach at the short and long term.
Keywords: Miniplates, miniscrews, molar intrusion, open bite, orthodontic, systematic
|How to cite this article:|
Al-Dhubhani MK. Stability of anterior open bite correction treated with posterior teeth intrusion using temporary anchorage devices. A systematic review. Saudi J Oral Sci 2018;5:69-74
|How to cite this URL:|
Al-Dhubhani MK. Stability of anterior open bite correction treated with posterior teeth intrusion using temporary anchorage devices. A systematic review. Saudi J Oral Sci [serial online] 2018 [cited 2018 Dec 12];5:69-74. Available from: http://www.saudijos.org/text.asp?2018/5/2/69/241166
| Introduction|| |
Nonsurgical correction of anterior open bite (AOB) is usually a difficult task for any orthodontist mainly because of high relapse tendency. Skeletal, dental, respiratory, neurologic, or habitual factors are all possible etiological factors. The treatment of AOB is usually aimed at obtaining an adequate amount of overlap of the maxillary and mandibular anterior teeth. Various treatment modalities were suggested in the literature for the treatment of AOB, the typical approach is orthodontic extrusion and retroclination of the anterior teeth, however, such treatment aimed only at camouflaging the underlying skeletal discrepancy. More sophisticated treatment modality is a combination of orthodontic and orthognathic surgical treatments in adulthood and more recently intrusion of posterior teeth by means of temporary anchorage devices (TADs).,,
Several authors reported successful true maxillary molar intrusion for the treatment of open bite, increased facial height, and supraerupted maxillary molars., Scheffler et al. found that a mean of 2.3 mm of true maxillary molars could be obtained using TAD. However, molars could be intruded up to 8 mm depending on their initial position and treatment targets.
Data regarding the stability of TAD-assisted AOB correction still are scarce in the literature. It has been found that AOB relapsed by 11.2% over 4 years in a sample of patients treated by zygomatic miniplates.
When conventional mechanics for treatment of AOB compared with TAD-assisted correction, better stability has been found in patients treated conventionally. In retrospective study, Baek et al. evaluated the relapse rate after 3 years of concluding treatment; 1.2 mm (17%) of overbite reduction was noted and 80% of total relapse occurs at the 1st year after treatment. Although 0.5–1.5 mm of molar intrusion relapse occurred, the positive overbite maintained in a sample of 33 patients and this could be explained by incisor extrusion after treatment.
| Materials and Methods|| |
The question this systematic review tried to answer is “Does TAD-assisted AOB correction is stable treatment modality?” The treatment plan of included studies should include utilization of any type of TAD to intrude maxillary, mandibular posterior teeth, or both and has a clear measure of overbite relapse after debonding. The primary outcome was the amount of overbite relapse after appliance debonding. The secondary outcome was the amount of relapse of intruded posterior teeth.
A systematic search of articles published from January 2000 to October 2017 was performed to retrieve randomized clinical trials (RCTs), nonRCTs, and retrospective studies (RTS) investigated the stability of TAD-assisted AOB correction. Ovid MEDLINE, PubMed, Embase, and the Cochrane Library databases were systematically searched for related articles. Independent search in selected orthodontic journals (the American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, European Journal of Orthodontics, Journal of Clinical Orthodontics, and Korean Journal of Orthodontics and Orthodontic Waves) was also performed. Articles that do not measure the posttreatment AOB change, case reports and series, and animal experiments and studies that involved patients in primary or mixed dentition stage or patients with craniofacial deformities and non-English articles were all excluded from this review. The key words used in the electronic search included “anterior open bite,” “molar intrusion,” and “posterior teeth intrusion,” which were crossed with “stability” and “outcome” [Table 1].
Study selection and data collection
The titles and abstracts of all articles obtained through the electronic searches were screened independently by two reviewers (MK and RR). After reading abstracts and removing the duplicates, a list of articles was generated for full-text screening by the same two reviewers. A consensus was reached among the reviewers about the articles that met the inclusion criteria.
Data were collected by the two reviewers (MK and RR) on data forms containing the following items: Year of publication, the design of study, material and methods, sample size, type of TAD used, amount of AOB reduction and amount of molar intrusion, follow-up period, amount of molar intrusion, and AOB relapse.
Risk of bias
A methodological quality scoring process was used to identify which selected studies would be most valuable. Methodological index for nonrandomized studies  was applied to assess the quality of involved studies.
| Results|| |
A total of 384 articles were recognized through electronic searches. Sixty-three duplicated articles were removed, and another 315 articles were excluded depending on their titles and abstracts. Thus, six articles remained for full-text screening. After full-text screening, another two articles were excluded because the full text of one of them  is only available in the Korean language, and the other one investigated the molar intrusion relapse but not the overbite relapse. Therefore, only four of those met the inclusion criteria of this review [Figure 1].
All included studies were retrospective except for Marzouk and Kassem, in which they performed a prospective controlled trial. The sample size was relative small in the studies maybe except for Scheffler et al. that involved 33 consecutive patients. However, the long-term follow-up (4 years) was only available for 25 patients. A total of 95 patients were successfully treated in all included studies with a wide age range from 13 to 49 years, and various intrusion techniques were used. The most common technique was buccal or zygomatic TAD attached to the upper molars by mean of power chains or coil springs ,, with transpalatal bar to prevent buccal flaring of the molars. Scheffler et al. used miniplates for nearly half of the sample (14 patients) and Marzouk and Kassem  used miniplates exclusively in their trial. It should be noted that no study evaluated the stability of AOB after intrusion of mandibular molars with or without maxillary molars. Marzouk and Kassem  was the only trial that specified the force magnitude for molar intrusion (450 g/side). Follow-up periods ranged from 1 year ,, to 4 years. All involved studies used linear cephalometric values to measure the overbite and posterior teeth intrusion. Maxillary first molar was used as representative of the amount of posterior teeth intrusion and subsequent relapse in all studies.,,, Detailed characteristics of the involved studies are illustrated in [Figure 2].
Risk of bias in the studies
Out of the four selected studies, only one was prospective controlled trial , and the other three studies were retrospective.,, The total quality scores of the included studies according to MINOR  ranged from 5 out of 12 to 10 out of 24 that indicate moderately to heavily biased studies. Comprehensive quality assessment considering specific methodological requirements is detailed in [Table 2].
Results of the individual studies
Interestingly, no randomized clinical trial was performed to assess the stability of TAD-assisted AOB correction perhaps due to new nature of such technique. In addition, only one retrospective study  compared results of this approach with other conventional methods of AOB treatment (i.e., combination of premolar extraction, anterior elastics and either accentuated-curve archwires or the multiloop edgewise archwire technique (MEAW) and high-pull headgear). In this study, although more AOB relapse after 2 years was reported in patient who had TAD (0.8 mm ± 1.1) than conventional method patient (0.5 mm ± 1.4), the difference was small and insignificant clinically and statistically (P ≥ 0.05). Relapse of posterior teeth intrusion was 0.5 mm ± 0.9 (P ≥ 0.05).
Baek et al. showed that AOB relapsed by 1.2 mm ± 1.44 at the end of 3 years of retention. However, most of the relapse (82%) occurred in the 1st year posttreatment (P ≤ 0.05). Molar intrusion showed small relapse (0.45 mm ± 0.46) at 3-year follow-up and again most of the relapse (95%) occurred at the 1st year of retention (P ≤ 0.05).
One of the RTS assessed in this review evaluated the AOB and posterior teeth intrusion relapse at 1-year and 2-year follow-up intervals. At 1 year of retention, only small relapse of AOB and posterior teeth intrusion was noted (0.3 mm ± 0.8 and 0.5 mm ± 1.1, respectively). Authors did not report whether such relapse was statistically significant or not. However, they evaluated the results of stability by percentage of patients who had clinically significant changes (>2 mm). Only 2 out 25 patients (8%) had more than 2 mm of overbite relapse, and 4 patients (16%) had more than 2 mm of maxillary molars reeruption (relapse).
The last study involved in this review was the only prospective trial with no control group. Marzouk and Kassem  showed (0.57 mm ± 0.09) of overbite relapse at 1 year of retention (P ≥ 0.05) and (0.31 mm ± 0.07) posterior teeth intrusion relapse (P ≥ 0.05). At the 4th year of retention, (0.77 mm ± 0.43 and 0.41 mm ± 2.03) of overbite relapse and posterior teeth intrusion relapse was found, respectively, which both were statistically insignificant.
Summary of results
Due to the heterogeneous variables in the involved studies, a meta-analysis was not possible. Large differences concerning the selection criteria and size of the samples were found. The samples studied comprised both growing and nongrowing participants and both extraction, nonextraction treatment approaches, wide spectrum of participants age with different types of malocclusions (i.e., Class I, Class II, and crowding). In addition, a different intrusion protocols with different type of TAD, force magnitude, treatment duration, and different retention protocols. Most importantly, the different studies enrolled patients with different initial AOB and maxillary molar alveolar heights.
| Discussion|| |
Several authors showed that intrusion of posterior teeth mainly upper molars using TAD are an effective strategy in the management of patients with dental or skeletal AOB.,, The mechanism behind this correction believed to be due anticlockwise mandibular rotation. In this paper, we systematically investigated the available scientific evidence regarding the stability of AOB treated by means of posterior teeth intrusion with TAD.
Out of four studies included in this review, two studies used miniscrews , one study used a combination of miniscrews and miniplates  and one study used miniplates exclusvily. All miniscrews were placed by orthodontists in contrast to miniplates that were placed by oral surgeons.
One of the most stable results of overbite and molar intrusion was reported by Scheffler et al. who reported less than half of millimeter of mean overbite relapse either at the short-term (1-year follow-up) or the long-term (≥2 years). Nevertheless, the initial AOB of the patients in this study was the smallest (1.2 mm ± 1.7) compared to other studies ,, and even some patients had a positive but shallow overbite (1.8 mm). In addition, this was the only study that used bonded occlusal splint covering the maxillary molars and premolars during intrusion phase which may aid in stability by creating better distribution of intrusive forces and in contrast to other studies they first achieved the posterior teeth intrusion before placement of fixed appliance.
Marzouk and Kassem  also showed low relapse rate for posterior teeth intrusion and overbite (mean; 0.41 and 0.77 mm, respectively) compared to Baek et al. and Deguchi et al. after 4 years of debonding. It should be noted that unlike other studies Scheffler et al. and Marzouk and Kassem  studies used miniplates as anchorage tool for posterior teeth intrusion and achieved the largest amount of molar intrusion (3.04 mm ± 0.79) compared to about 2 mm of mean molar intrusion in other studies. Thus, it could be speculated that the more the molar intrusion during treatment, the more the stability of overbite after treatment. Interestingly, although relapse of molar intrusion seems to be comparable in all involved studies in this review (ranged from 0.3 to 0.5 mm), the overbite relapse showed large differences (ranged from 0.3 to 1.2 mm) which may indicate that molar reeruption (relapse) is not the sole etiological factor of overbite relapse posttreatment and another factor such as compensating incisor extrusion,, facial growth, and the treatment strategy itself may contribute in the overbite maintenance.
Three studies ,, have followed the patients at two time intervals, and most (80% to 95%) of the total relapse has occurred at the 1st year out of treatment, and any further relapse after that is small and insignificant clinically. Moreover, when molar intrusion stability compared with overbite stability, the former showed more stability after the 1st year of follow-up.,,,
Deguchi et al. was the only comparative study in this review where they compared the stability of AOB correction treated with TAD or with conventional methods. Patients treated without TAD had received premolars extraction and combination of anterior elastics and either accentuated curve of Spee archwires or the MEAW and a high pull headgear. The results of this study showed that AOB treated conventionally is slightly more stable after 2 years of retention which could be explained by the fact that patients with in TAD group had more skeletal components of the AOB than conventional method group. The authors recommended applying of extra measures in AOB patients treated with TAD such as the use of occlusal stops in the mandibular molars, myofunctional therapy and keeping TAD during retention period to maximize the stability.
Baek et al. was among the first published articles that assessed the AOB stability of patients treated by maxillary molar intrusion in a small sample size of adult patients (n = 9); The AOB was treated either by buccal and lingual miniscrews or with buccal miniscrews and transpalatal arch. This retrospective study showed the higher relapse rate of AOB among all studies in this review (1.2 mm ± 1.44) after 3 years of retention. While one study  failed to find a correlation between initial AOB severity and the amount of subsequent relapse, another study  found a positive correlation and the both studies , found a negative correlation between the amount of overbite correction and posterior teeth intrusion and the extent of subsequent relapse.
Regarding the retention protocol, two studies , used a combination of fixed lingual retainers and removable retainers while Marzouk and Kassem  used only removable upper and lower retainers with posterior bite plane. Deguchi et al. gave no description of retention protocol. Indefinite retention was recommended in all those studies.,,
Active retention in the form of elastics attached between removable retainer and miniscrews in the first 6 months of retention was prescribed in one study  that showed low relapse rate of molar intrusion and overbite.
Only four studies met the inclusion criteria of this review with no RCTs. RCTs with proper randomization and control groups are mandatory to compare the stability of AOB treated by TAD with other treatment modality. It is also interesting to compare the failure rate of AOB after using different intrusion protocols. The absence of control groups, small sample size, and confounding factors are the most common disadvantages of the involved studies. Only the 1st maxillary molar relapse was measured in all studies; nevertheless, it is important to investigate the effect of different posterior teeth relapse on the relapse of the overbite.
| Conclusion|| |
Currently, there is weak evidence with low level of certainty that correction of AOB by posterior teeth intrusion with TAD is quite stable treatment strategy at the short- and long-term. Four years after debonding, overbite relapsed by 0.3 to 1.2 mm and molar intrusion showed between 0.3 and 0.5 mm of relapse and most of this relapse occurred at the 1st year after debonding. Thus, strict retention protocol is highly recommended. Well-conducted RCTs are urgently needed to reach robust scientific evidence.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]