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Prospective clinical trial comparing the effects of conventional Twin-block and mini-block appliances: Part 1. Hard tissue changes.
Am J Orthod Dentofacial Orthop. 2005 Apr; 127(4):465-72; quiz 517.AJ

Abstract

PURPOSE

The aim of this prospective clinical trial was to compare the dentoskeletal effects of a conventional and a modified Twin-block (TB) appliance. The conventional TB appliance was constructed with a large, single-step advancement. The modified appliance, termed the mini-block (MB), was incrementally advanced, incorporated a maxillary incisor torquing spring, and had a reduced bite-block height.

MATERIAL

Seventy patients were placed into age- and sex-matched pairs. Patients in each pair were allocated to opposing appliance groups. Active treatment lasted 9 months, irrespective of the final overjet attained, and final cephalometric records were taken at 12 months (+/-1 month). Both groups showed pretreatment equivalence for age, sex, overjet, and cephalometric variables.

RESULTS

The TB group experienced a significantly greater reduction in overjet (median, -8 mm; P = .02) compared with the MB group (median, -4 mm). This improved overjet reduction was associated with significantly greater forward movement of pogonion (median change, TB: 3.3 mm; MB: 2.1 mm; P = .02) and greater retroclination of the maxillary incisors (median change, TB: -5 degrees ; MB: -1.9 degrees ; P = .04). No significant intergroup difference was found for changes in total anterior facial height (median change, TB: 4.4 mm; MB: 4.3 mm) and mandibular incisor proclination (median change, TB: 1.3 degrees ; MB, 2.4 degrees).

CONCLUSIONS

Progressive mandibular advancement was not associated with greater mandibular growth compared with single-step advancement. The maxillary incisor torquing spring seems to be effective at reducing maxillary incisor retroclination. Reduced bite activation in the MB group did not result in less mandibular incisor proclination. There was considerable individual variation in appliance effects within both groups.

Authors+Show Affiliations

The Royal London Hospital. daljit_s_gill@yahoo.co.ukNo affiliation info available

Pub Type(s)

Clinical Trial
Comparative Study
Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

15821691

Citation

Gill, Daljit S., and Robert T. Lee. "Prospective Clinical Trial Comparing the Effects of Conventional Twin-block and Mini-block Appliances: Part 1. Hard Tissue Changes." American Journal of Orthodontics and Dentofacial Orthopedics : Official Publication of the American Association of Orthodontists, Its Constituent Societies, and the American Board of Orthodontics, vol. 127, no. 4, 2005, pp. 465-72; quiz 517.
Gill DS, Lee RT. Prospective clinical trial comparing the effects of conventional Twin-block and mini-block appliances: Part 1. Hard tissue changes. Am J Orthod Dentofacial Orthop. 2005;127(4):465-72; quiz 517.
Gill, D. S., & Lee, R. T. (2005). Prospective clinical trial comparing the effects of conventional Twin-block and mini-block appliances: Part 1. Hard tissue changes. American Journal of Orthodontics and Dentofacial Orthopedics : Official Publication of the American Association of Orthodontists, Its Constituent Societies, and the American Board of Orthodontics, 127(4), 465-72; quiz 517.
Gill DS, Lee RT. Prospective Clinical Trial Comparing the Effects of Conventional Twin-block and Mini-block Appliances: Part 1. Hard Tissue Changes. Am J Orthod Dentofacial Orthop. 2005;127(4):465-72; quiz 517. PubMed PMID: 15821691.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Prospective clinical trial comparing the effects of conventional Twin-block and mini-block appliances: Part 1. Hard tissue changes. AU - Gill,Daljit S, AU - Lee,Robert T, PY - 2005/4/12/pubmed PY - 2005/5/3/medline PY - 2005/4/12/entrez SP - 465-72; quiz 517 JF - American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics JO - Am J Orthod Dentofacial Orthop VL - 127 IS - 4 N2 - PURPOSE: The aim of this prospective clinical trial was to compare the dentoskeletal effects of a conventional and a modified Twin-block (TB) appliance. The conventional TB appliance was constructed with a large, single-step advancement. The modified appliance, termed the mini-block (MB), was incrementally advanced, incorporated a maxillary incisor torquing spring, and had a reduced bite-block height. MATERIAL: Seventy patients were placed into age- and sex-matched pairs. Patients in each pair were allocated to opposing appliance groups. Active treatment lasted 9 months, irrespective of the final overjet attained, and final cephalometric records were taken at 12 months (+/-1 month). Both groups showed pretreatment equivalence for age, sex, overjet, and cephalometric variables. RESULTS: The TB group experienced a significantly greater reduction in overjet (median, -8 mm; P = .02) compared with the MB group (median, -4 mm). This improved overjet reduction was associated with significantly greater forward movement of pogonion (median change, TB: 3.3 mm; MB: 2.1 mm; P = .02) and greater retroclination of the maxillary incisors (median change, TB: -5 degrees ; MB: -1.9 degrees ; P = .04). No significant intergroup difference was found for changes in total anterior facial height (median change, TB: 4.4 mm; MB: 4.3 mm) and mandibular incisor proclination (median change, TB: 1.3 degrees ; MB, 2.4 degrees). CONCLUSIONS: Progressive mandibular advancement was not associated with greater mandibular growth compared with single-step advancement. The maxillary incisor torquing spring seems to be effective at reducing maxillary incisor retroclination. Reduced bite activation in the MB group did not result in less mandibular incisor proclination. There was considerable individual variation in appliance effects within both groups. SN - 0889-5406 UR - https://www.unboundmedicine.com/medline/citation/15821691/Prospective_clinical_trial_comparing_the_effects_of_conventional_Twin_block_and_mini_block_appliances:_Part_1__Hard_tissue_changes_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0889540604010005 DB - PRIME DP - Unbound Medicine ER -