Introduction
Our objective was to perform a systematic review of studies pertaining to the distalization of teeth with appliances reinforced with temporary skeletal anchorage devices.
Methods
PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Knowledge, Ovid, and Scopus were searched until the second week of August 2010 to identify all articles reporting on the use of orthodontic implants or miniplates in distalization of teeth. The quality of the relevant studies was ranked on an 11-point scale, from low to high quality.
Results
Twelve relevant articles were identified. The distal movement of the maxillary molars was from 3.3 to 6.4 mm; the concomitant molar distal tipping was from 0.80° to 12.20°. The maxillary incisors remained stable during molar distalization. The assessment of study quality showed that 8 studies were of low and 4 of medium quality.
Conclusions
Molar distalizers reinforced with the temporary skeletal anchorage devices seem to effectively move molars distally without unwanted mesial incisor tipping. Because of the lack of high-quality studies, however, the findings of this study should be interpreted with caution.
Distalization of the molars has become a popular nonextraction treatment alternative in some patients with Class II malocclusions. There are numerous methods to move teeth distally; some techniques require a patient’s active compliance, whereas others do not. Because patients’ cooperation during orthodontic treatment is frequently problematic, the appliances that eliminate the need for compliance are usually deemed superior to those demanding cooperation. Although popular noncompliance appliances, such as the pendulum and the distal jet, are effective in distalizing molars, the distalization process is associated with the concomitant loss of anterior anchorage. Sfondrini et al critically evaluated various appliances used for molar distalization and found that most noncompliant appliances were associated with mesial movement or tipping of the incisors, synonymous with loss of anchorage. Similar conclusions were made by Antonarakis and Kiliaridis, who systematically reviewed the effects of noncompliance tooth-borne distalizers. They found that distalization of molars is related to unavoidable loss of anchorage, which was observed as premolar mesial movement and incisor mesial crown and tipping movements.
To reinforce anchorage and reduce unwanted movement of the incisors and premolars, a temporary skeletal anchorage device (TSAD) can be used. The TSAD is defined as a device that is temporarily fixed in bone for reinforcement of orthodontic anchorage. Because a TSAD is stable, it provides absolute anchorage. To date, many distalization appliance designs incorporating TSADs have been developed. They range from the skeletal anchorage system (SAS) with miniplates placed in the zygomatic region in the maxilla or retromolar region of the mandible to appliances supported by a single orthodontic implant in the anterior palate. Although the current studies suggest that these appliances might be effective in moving molars distally, an in-depth analysis is needed to investigate also other aspects of distalization, such as a rate and duration of molar movement. Therefore, the objectives of this systematic review were to evaluate the effectiveness of the distalization of molars with distalizers supported with TSADs and to compare the effectiveness of TSAD-reinforced distalizers with tooth-borne noncompliance distalization appliances.
Material and methods
PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Knowledge, Ovid, and Scopus were searched until the second week of August of 2010 to identify all articles reporting on the use of TSADs in distalization of molars. The search strategy used in this review is shown in Table I .
| 1. | orthodontic ∗ |
| 2. | micro-implant ∗ OR microimplant ∗ OR “micro implant ∗ ” |
| 3. | mini-implant ∗ OR “mini implant ∗ ” |
| 4. | “orthodontic implant ∗ ” |
| 5. | “mini-plate ∗ ” OR “mini plate ∗ ” |
| 6. | “palatal implant ∗ ” OR “midpalatal implant ∗ ” |
| 7. | “buccal implant ∗ ” |
| 8. | miniscrew ∗ OR mini-screw ∗ OR “mini screw ∗ ” |
| 9. | microscrew ∗ OR micro-screw ∗ OR “micro screw ∗ ” |
| 10. | 2 OR 3 OR 4 OR 5 OR 6 OR 7 OR 8 OR 9 |
| 11. | 1 AND 10 |
Based on the data from titles and abstracts of the retrieved studies, both authors independently selected articles that met the following inclusion criteria.
- 1.
Studies on human subjects, published in English.
- 2.
Studies that included clear descriptions of the distalization appliance and the technique.
- 3.
Prospective or retrospective original studies (case reports and review and summary articles were excluded).
- 4.
Studies with minimum 10 subjects in the sample.
The reference lists of these articles were perused, and references related to the articles were followed up. If there was disagreement between the authors, inclusion of the study was confirmed by mutual agreement.
From the identified articles, the authors independently extracted data referring to year of publication, type of study, sample size, site of implant or miniplate placement, type of distalizing appliance, magnitude of force exerted on the teeth, duration of treatment, age at the start of treatment, presence of second molars, calculation of the method error, amounts of molar retraction and tipping, and changes of the position of the central incisors ( Table II ).
| Study | Type of study; consecutive patients (Y, N); control group (Y, N) | Sample size | Age at start of treatment in years (SD) | Site of placement of the TSAD | TSAD diameter, length | Osseointegration (Y or N) | Distalization appliance | Magnitude of force |
|---|---|---|---|---|---|---|---|---|
| Cornelis and De Clerck, 2007 | Retrospective; Y; N | 17 (15 female, 2 male) | 27.3 (NR) | Infrazygomatic crest | Miniplate | N | Elastics attached to maxillary fixed appliance | 150 g |
| Escobar et al, 2007 | Retrospective; Y; N | 15 (6 girls, 9 boys) | 13 (2.1) | Anterior palate | 2 implants: 2.0 mm, 11 mm | N | Modified pendulum appliance | 250 g |
| Gelgör et al, 2004 | Prospective; NR; N | 25 (18 girls, 7 boys) | 13.8 (NR) | Anterior palate | 1.8 mm, 14 mm | N | Transpalatal bar between premolars supported by implant and nickel-titanium open coil between premolar and molar on the buccal side | 250 g |
| Gelgör et al, 2007 ∗ | Retrospective; N; Y | 20 (8 girls, 12 boys) | NR (NR); range, 11.6-15.1 | Anterior palate | 1.8 mm, 14 mm | N | Transpalatal bar between premolars supported by implant and nickel-titanium open coil between premolar and molar on the buccal side | 250 g |
| Gelgör et al, 2007 † | Retrospective; N; Y | 20 (11 girls, 9 boys) | NR (NR); range, 12.3-15.4 | Anterior palate | 1.8 mm, 14 mm | N | Appliance consisting of acrylic palatal button attached to implant, premolar rests, and nickel-titanium open coils on the lingual side | 250 g |
| Kinzinger et al, 2009 | Retrospective; N; N | 10 (8 girls, 2 boys) | 12.1 (NR) | Anterior palate | 1.6 mm, 8-9 mm | N | Distal jet | 200 g |
| Kircelli et al, 2006 | Prospective; NR; N | 10 (9 girls, 1 boy) | 13.5 (1.8) | Anterior palate | 2.0 mm, 8 mm | N | Pendulum appliance | NR |
| Oberti et al, 2009 | Prospective; NR; N | 16 (4 girls, 12 boys) | 14.3 (NR) | Anterior palate | 2 implants: 2.0 mm, 11 mm | N | Dual–force distalizer | 250-300 g |
| Oncag et al, 2007 | Retrospective; Y; Y | 15 (9 girls, 6 boys) | NR (NR) | Anterior palate | 3.8 mm; 9 mm | Y | Pendulum springs made of beta nickel-titanium wire | 300 g |
| Park et al, 2005 | Retrospective; Y; N | 13 (8 girls, 5 boys) | 17.9 (5.7) | 9 patients: Mn implants distal to second molars or in retromolar area; 2 patients: Mx implants in buccal alveolar bone between second premolars and first molars; 2 patients: both Mn and Mx implants | various | NR | Nickel-titanium coils and elastomeric thread | 200 g |
| Polat-Ozsoy et al, 2008 | Retrospective; N; Y | 22 (15 girls, 7 boys) | 13.6 (2.0) | Anterior palate | 2.0 mm, 8 mm | N | Pendulum appliance | 230 g |
| Sugawara et al, 2004 | Retrospective; N; N | 15 (12 female, 3 male) | 26.9 (NR) | Anterior margin of mandibular ramus | Titanium plates | N | SAS | NR |
| Sugawara et al., 2006 | Retrospective; N; N | 25 (22 female, 3 male) | 23.9 (NR) | Infrazygomatic crest | Titanium plates | N | SAS | NR |
| Study | Treatment duration in months (SD) | Presence of second molars | Method error | Amount of molar distal movement/tipping (mm/°) | Monthly rate of molar movement (mm) | Amount of central incisor mesial movement/tipping (mm/°); negative value for distal movement/tipping | Success rate |
|---|---|---|---|---|---|---|---|
| Cornelis and De Clerck, 2007 | 7.0 (2.0) | 100% | N | 3.3/1.8 | 0.5 | −1.4/NR | 100% |
| Escobar et al, 2007 | 7.8 (NR) | NR | Intraclass correlation coefficient | 6.0/11.2 | 0.8 | –0.5/–2.5 | Unclear |
| Gelgör et al, 2004 | 4.6 (NR) | 88% | Dahlberg’s method | 3.9/8.8 | 0.8 | 0.5/1.0 | NR |
| Gelgör et al, 2007 ∗ | 4.6 (NR) | 90% | Dahlberg’s method + correlational analysis | 4.0/9.1 | 0.7 | –0.5/–1.1 | NR |
| Gelgör et al, 2007 † | 5.4 (NR) | 85% | Dahlberg’s method + correlational analysis | 3.9/0.8 | 0.7 | –0.1/–0.1 | NR |
| Kinzinger et al, 2009 | 6.7 (NR) | 20% fully erupted, 25% erupting | N | 3.8/3.0 | 0.6 | –0.4/–0.6 | NR |
| Kircelli et al, 2006 | 7 (1.8) | NR | Spearman correlation coefficient between repeated measurements | 6.4/10.9 | 0.9 | –0.2/–0.6 | NR |
| Oberti et al, 2009 | 5 (NR) | Unerupted or just recently erupted | Intraclass correlation coefficient | 5.9/5.6 | 1.2 | –0.5/–0.8 | NR |
| Oncag et al, 2007 | 6.2 (NR) | NR | ANOVA test | 4.0/12.2 | 0.6 | Right side, 0.1/1.0 Left side, –2/–0.6 |
NR |
| Park et al, 2005 | 12.3 (5.7) | Mostly present | Paired t test | Mn first molars, 2.9/5 | ∗ | Mn central incisors, NR | 90% |
| Polat-Ozsoy et al, 2008 | 6.8 (1.7) | 13.6% | Spearman correlation coefficient between repeated measurements | 4.8/9.1 | 0.7 | –0.1/–1.7 | Unclear |
| Sugawara et al, 2004 | 28.9 (NR) | 100% | Unclear | 3.5/NR; tipping ratio, 46.3% |
0.1 | NR | NR |
| Sugawara et al, 2006 | 19 (NR) | 100% | Unclear | 3.8 mm crown, 3.2 mm root | 0.2 | NR | NR |
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