European Journal of Onhodonlks 13 (1991) 53-58

© 1991 European Orthodonuc Society

The effect of Andresen, Harvold, and Begg treatment on overbite and molar eruption Judith V. Ball and N. P. Hunt Institute of Dental Surgery, London, England SUMMARY A retrospective cephalometric study was carried out to compare the vertical dental changes between patients treated with the Andresen (30), Harvold (19), or Begg (30) appliances, and an untreated control group (24). It was found that all three appliances successfully reduced the overbite although the reduction tended to be more stable with the functional appliances. Overbite was reduced by a combination of factors which varied according to the appliance used, but included lower incisor intrusion or restraint, molar eruption, vertical growth of the face and lower incisor proclination in the functional groups. Relapse appeared to be primarily due to continued lower incisor eruption, retroclination of these teeth, and forward rotation of the mandible with continued growth.

In Class II division 1 malocclusions with an increased overbite it is essential that treatment mechanics facilitate overbite reduction in order that the overjet may be fully reduced. Opinions have differed as to how overbite reduction may be achieved. Considering the Begg appliance, Begg and Kesling (1977) stated that it was due to intrusion of the lower incisors in response to the anchor bend, the molars remaining stationary. However, most clinicians have found that considerable molar elevation occurred with the lower incisors being intruded or merely restrained (Swain and Ackerman, 1969; Rodesano, 1972; Williams, 1977). The molar response was likely to have resulted from the extrusive component of the Class II elastics. The upper incisors, however, resisted extrusion due to the opposing force of the anchor bend. The upper molar was found to erupt, but less than the lower molar because it was not under the influence of the inter-maxillary traction (Bijlstra, 1969). Overbite relapse was reported to be 20 per cent by Grano (1971). The cause was supposedly relapse of both lower incisor intrusion (Levin, 1977) and molar extrusion (O'Reilly, 1979), although Williams (1977) commented that the overbite was stable if the inter-incisal angle had been adequately corrected. Forward growth

rotation may also be a contributory factor (Bjork andSkieller, 1972). In contrast to fixed appliances, functional appliances rely on passive eruption of the buccal segments and where lower incisor capping is present restraint of these teeth to bring about overbite reduction. Where the upper buccal segments are restrained as with the Harvold appliance only lower molar eruption can occur. Despite the fact that no active force is used it has been found in several studies that molar eruption is increased in excess of the control by up to 0.5 mm/annum (Harvold and Vargervik, 1971; Wieslander and Lagerstrom, 1979). Righellis (1983) commented that the amount of eruption was dependent on appliance design. Long-term studies, however, have indicated no difference in molar position between control and treated groups (Calvert, 1982). Restraint of the lower incisors was also found to be minimal in the long term (Wieslander and Lagerstrom, 1979). Lower incisor proclination is a feature which may occur with the use of functional appliances. It can, however, be minimized by the use of lower incisor capping or relief of the acrylic lingual to the lower incisors. In the long term, proclination that has occurred tends to relapse (Wieslander and Lagerstrom, 1979) although any residual proclination will have contributed to overbite reduction. The literature, therefore, demonstrates that

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Introduction

54

J. V. BALL AND N. P. HUNT

graph (XR1) was taken no more than 6 months prior to the start of treatment and as close to 12 years as possible. A second radiograph (XR2) corresponded to the end of all appliance wear and included a short period of retention with an upper removable retainer in most of the Begg cases and part-time wear in the functional cases. The third radiograph (XR3) corresponded to at least 1 year out of retention and as close to 16 years as possible (Table 1). The majority of patients were observed between 1 and 2 years out of retention. The longer observation periods represent patients who started treatment slightly earlier or for whom treatment was completed rapidly. The minimum value is less than 1 year out of retention in four cases because XR2 was taken a few months post-treatment.

Subjects

Methods

Standardized lateral skull radiographs with the teeth in occlusion were obtained from patients with a Class II division 1 malocclusion as defined by the British Standards Institute (1983). The first group consisted of 30 patients treated with the Andresen appliance; the second of 30 patients treated with the Begg appliance and the extraction of four first premolars; and the third of 19 patients treated with the Harvold activator. The control group included 24 patients with an untreated and, therefore, less severe Class II division 1 malocclusion. A pretreatment radio-

Radiographs were traced under optimum contrast with a 4H pencil on 60 gsm tracing paper. Duplicated landmarks were identified by constructing the mid-point of the two structures. The landmarks were digitized using a GTCO DIGI-PAD 5™ (GTCO Corp., 1055 1st St Rockville, Maryland 20850, U.S.A.) digitizer linked to a Hewlett-Packard HP86B (HewlettPackard Ltd., Bridewell House, London EC4) computer. Each radiograph was digitized twice and values accepted if the difference was no more than 0.2 mm. A personalized computer program

Table 1 Material: age and sex distribution.

Males (n) Females (n) Total (n)

Control 1

Andresen

Begg

Harvold

18 6 24

14 16 30

12 18 30

8 1! 19

Age (years) Mean

s.d.

Mean

s.d.

Mean

s.d.

Mean

s.d.

X-ray 1 2 3 2-1 3-1

11.8 — 16.0 — 4.2

0.5 0.6 — 0.6

12.0 14.1 15.8 2.1 3.8

0.7 1.0 0.9 0.8 1.0

11.9 14.2 16.0 2.3 4.1

0.6 0.7 0.5 0.7 0.7

12.1 13.6 15.4 1.5 3.5

1.4 1.4 1.8 0.6 1.3

Range 3-2





0.9-4.9

0.7-3.1

0.7-4.0

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the mechanism of overbite reduction is complex and multifactorial, including molar eruption and lower incisor restraint and proclination. Vertical facial growth and backward mandibular rotation have been found to occur during treatment and may also contribute to overbite reduction, although the latter has been found to be a temporary occurrence (Menezes, 1985; Andersson and Ahlgren, 1977; O'Reilly, 1979; Calvert, 1982). Some degree of overbite relapse was a consistent finding in all studies, but the aetiology has not been fully resolved. Factors implicated have included a relapse of vertical dental changes, uprighting of the lower incisors and forward growth rotation (Grano, 1971; Bjork and Skieller, 1972; Menezes, 1975).

55

OVERBITE AND MOLAR ERUPTION

Results The results are presented in Table 3 and include the initial mean values and the mean changes during treatment (XR 2-1) and over the whole observation period (XR 3-1). Statistical comparisons made in this table have levels of confidence denoted by asterisks (*/ >

The effect of Andresen, Harvold, and Begg treatment on overbite and molar eruption.

A retrospective cephalometric study was carried out to compare the vertical dental changes between patients treated with the Andresen (30), Harvold (1...
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