Table 5 Study outcome characteristics
Measurement record | Outcome measurement | Age at outcome measurement | Mean mandibular anterior crowding | Mandibular second molar eruption problems | Other findings | Eruption difficulty | |
|---|---|---|---|---|---|---|---|
Ferro et al. [15] | Panoramic radiograph | Mandibular second molar considered erupted once it reached the functional occlusal plane with its mesial marginal ridge at the same level of the mandibular first molar’s distal marginal ridge | Treatment group (13.4 years) | Treatment group (3.8 mm; SD, 1.3) | Treatment group: 18 (impaction) + 41 (ectopic eruption), Total patients- 59 (22%) | 9 patients showed bilateral impaction in treatment group; 1 patient showed bilateral impaction in untreated group | 22% |
Impaction diagnosed for molars whose eruption was interrupted before gingival emergence by physical barrier or abnormal dental position and closed apices of the roots | Control group (13.8 years) | Control group (4.8 mm; SD, 2.1) | Control group: 2 (impaction) + 2 (ectopic eruption), Total patients- 4 (2.96%) | ||||
Jacob et al. [19] | Panoramic radiograph | Not specified | Not specified | Not specified | Treatment group: 8 patients (11.9%) | Five (7.5%) patients showed unilateral second molar impaction while three (4.5%) showed bilateral impaction | 11.9% |
Rubin et al. [17] | Treatment group- Panoramic radiograph | No eruption difficulty when, with the root formed for 75% of its length or more, the second molar had erupted in the oral cavity | Treatment group (13.3 years) | 2–4.5 mm | 4.7% had eruption difficulty; 1% in the control group | Mandibular lingual holding arch- 4.7% | |
Control group- Lateral oblique radiograph | Eruption difficulty, when the root of the mandibular second molar was at least 75% formed, but the tooth remained unerupted | Control group (12.8 years) | |||||
Sonis and Ackerman [16] | Panoramic radiograph | Mandibular second molar impaction was defined as incomplete eruption when the distal cusps of the second molar were clinically visible and the mesial cusps were radiographically confirmed below the height of contour of the distal surface of the mandibular first molar | Not specified | 29 patients had at least one impacted second molar (14.5%). [Twenty-four patients had unilateral impactions, and five were bilateral] | 14.5% | ||
Arevalo et al. [18] | Panoramic radiograph and/or periapical radiograph | Second molar impaction was defined as incomplete eruption when 75 percent of the roots had formed, and the distal cusp might be clinically visible but the mesial was radiographically confirmed below the height of contour of the distal surface of the mandibular first molar | Not specified but age controlled | Not specified | Treatment group: 18 teeth; 10 patients (impaction), 7.1% | 7.1% | |
Control group: 4 teeth; 2 patients (impaction), 1.5% |