Lower Labial Segment Research Articles

The iatrogenic anterior open bite; a potential side-effect of thermoplastic orthodontic retainers

Abstract: Thermoplastic orthodontic retainers are popular with both patients and clinicians. Tooth coverage provides retention of orthodontic alignment, particularly in the lower labial segment, and their aesthetics are improved in comparison with more traditional acrylic and wire varieties. Iatrogenic side-effects are possible if the design is inadequate. Lack of coverage of terminal molars can allow overeruption, causing an anterior open bite. This report describes an anterior open bite caused by an inadequate thermoplastic retainer and management using a Hawley type retainer to improve the open bite which had arisen. CPD/Clinical Relevance: The provision of orthodontics has grown and with this the potential for detrimental occlusal effects due to inadequate extension of occlusal coverage appliances such as retainers and clear aligners.

The Quatro appliance: a removable aligner with a changeable labial bow

Lower labial segment irregularity is a feature that is presenting more frequently as greater emphasis is placed on aesthetics than ever before. The authors report on a removable appliance that is easy to construct and use and is designed to deal with mild labial tooth irregularity. In cases of crowding the aligner can be used in conjunction with inter-proximal stripping. The device incorporates a removable labial bow attached bilaterally to a sliding lock. This lock permits the addition of sectional archwires to the labial part of the appliance. The versatility of the aligner allows round and rectangular wires of different materials and dimensions to be placed with or without bends.

Mandibular incisal edge demineralization and caries associated with Twin Block appliance design

Demineralization and caries are well documented and unwanted complications of orthodontic therapy. These are most commonly reported in relation to fixed appliance therapy. Five cases are presented of patients undergoing Twin Block appliance therapy with the appliances incorporating lower labial segment capping, illustrating a pattern of demineralization and caries of the incisal tips of the mandibular labial segment, influenced by the incisal capping and the frequent intake of carbonated soft drinks.

Developmental Changes in Alignment of the Lower Labial Segment

The purpose of this study was to examine changes in lower incisor alignment at various developmental stages, from the time of eruption to the established permanent dentition and to try to predict the degree of crowding in the permanent dentition from that observed at earlier developmental stages. Forty-eight subjects (20 male, 28 female) with intact mandibular arches were selected from the Belfast growth study records. The lower incisor space condition was measured at each of four developmental stages: (1) initial eruption of the lower permanent incisors; (2) initial eruption of the permanent canines; (3) initial eruption of the second molars; (4) 3 years after eruption of the second molars. Differences in lower incisor space condition between each developmental stage were investigated and correlation analyses between the space conditions at each stage were carried out. On average, crowding of the lower incisors decreased to a statistically significant degree (- 0.9 mm) between stages 1 and 2, and increased between stages 3 and 4 (0.4 mm). Significant correlation coefficients between space condition at each developmental stage were found, but were considered unreliable as predictors of lower incisor crowding in the mature dentition.

Lower Incisor Torque: The Effects of Rectangular Archwires with a Reverse Curve of Spee

The relationship between the Curve of Spee in a rectangular archwire and torque in the lower labial segment is discussed. It is concluded that introducing a reverse curve in the archwire does not necessarily have any adverse effects on final lower incisor inclination.

The Effects of Begg Treatment on the Lower Labial Segment in Class II Cases

A report is presented on eleven Class II cases which had been treated by the Begg technique. The cases were analysed from 1 to 3·5 years following retention, with particular emphasis being placed on changes to the lower labial segment. Where relevant, comparisons are made with growth study standards. The use of the lower incisor—Mandibular planes angle (IMPA) is described and criticized and an alternative linear measurement is used to describe changes in the sagittal position of the lower incisors. The results indicate that despite widely held views, it is possible to obtain stable results, following radical alteration to the lower incisor position. There was a trend towards an overall lingual movement of lower incisor apices.