Evaluation of Skeletal and Dental Effects of Lower Lingual Arches.

OBJECTIVE: A lower lingual arch is usually recommended as a holding device to maintain arch length and to prevent mesial migration of the mandibular first molars. Despite its widespread use, comparatively little is known about the effects of a lower lingual holding arch on preservation of lower arch dimensions and tooth position and the impact of the device on mandibular growth. The aim of this study is to evaluate the skeletal and dental effects of the lower lingual holding arch with regard to arch dimension, positions of mandibular molars and incisors, and usual mandibular growth. STUDY DESIGN: Thirty-four children (18 males and 16 females) who needed space maintainers were included in the present study. The patients were divided into two groups according to whether they were missing second primary molars on one or both sides. Group I comprised 16 children (8 males and 8 females, average age 8.8 ± 0.9 years) with a missing second primary molar on one side; Group II comprised 18 children (10 males and 8 females, average age 8 ± 0.7 years) with extractions on both sides. Lateral cephalograms, dental pantomograms, and study casts of the patients were taken at the beginning and the end of the study period. Average treatment time was 20.4 ± 4 months. RESULTS: Lower incisors moved forward and Incisor Mandibular Plane Angle (IMPA°) increased in both treatment groups. Statistically significant differences between the groups were found when comparing pre-treatment and post-treatment arch dimension and position of mandibular molars. Results were better for lingual arches with extraction on one side than with extraction on both sides Conclusions: A lingual arch seems to be an effective tool for maintaining arch length, and was not found to impair mandibular growth.

Modified distal shoe appliance--fabrication and clinical performance.

When the primary second molar is prematurely lost, mesial movement and migration of the permanent first molar often occurs. This is one of the most difficult problems of the developing dentition confronted by pediatric dentists. Use of a space maintainer that will guide the permanent first molar into its normal position is indicated. In cases with bilateral premature loss of primary molars, the conventional design of distal shoe poses a variety of problems and, therefore, necessitates a customized design for the eruption guidance of permanent first molars. The purpose of this case report is to discuss an innovative design of a distal shoe appliance, which was used with good clinical results.

Effects of lingual arch used as space maintainer on mandibular arch dimension: a systematic review.

INTRODUCTION: The aim of this systematic review was to examine the effects of a lingual arch on mandibular arch dimensions when it is used as a space maintainer. METHODS: PubMed, Medline, Lilacs, Cochrane Central, and Cochrane Database of Systematic Reviews were surveyed for articles published between January 1980 and January 2009. Inclusion criteria were human subjects, prospective or retrospective method, effect of the lingual arch used as space maintainer in the mandibular arch, and publication in English. RESULTS: Of the 262 studies identified in the search, only 2 met the final inclusion criteria. CONCLUSIONS: The results showed that the lingual arch is effective for controlling mesial movement of molars and lingual tipping of incisors.

A randomized clinical trial to compare the Goshgarian and Nance palatal arch.

The aim of this trial was to evaluate whether a Nance or Goshgarian palatal arch was most effective for prevention of mesial drift, distal tipping, prevention of mesio-palatal rotation of the upper first permanent molars, and patient comfort and ease of removal. Patients were recruited from a district general hospital and a specialist orthodontic practice and randomly allocated to a Goshgarian (n = 29) or a Nance (n = 28) group. Pre-treatment study models (T1) were taken followed by the placement of the palatal arch, premolar extractions, and upper and lower fixed appliances. The clinical end point was 6 months (T2), at which time, an impression for an upper study model was taken. The amount of upper first permanent molar mesial movement, distal tipping, and mesio-palatal rotation was measured by scanning T1 and T2 study models and then using a software program to calculate molar changes. In addition, the patients recorded their discomfort scores using a seven-point Likert scale at each recall visit. Forty-nine patients (86 per cent) completed the trial. t-tests were used to compare molar movements between the Goshgarian and Nance palatal arch groups. There were no statistically significant differences between the palatal arches in terms of prevention of mesial drift or distal tipping (P > 0.05). There was a statistically significant difference in the amount of molar rotation between the arch types, with both exhibiting some disto-palatal rotation even though they were not activated for this movement. The Goshgarian palatal arch produced marginally more disto-palatal rotation than the Nance arch (P = 0.02), although this may not be considered clinically significant. A Mann-Whitney test revealed that there was also a statistically significant difference in pain scores between the Goshgarian and the Nance arch, with the latter being associated with more discomfort (P = 0.001). This trial did not support any preference in the use of the Goshgarian or Nance palatal arch, unless the slightly reduced patient discomfort with the Goshgarian arch is considered significant.

Manejo de las discrepancias en la longitud del arco mandibular: oportunidad del tratamiento / Managing mandibular arch lenght discrepancies: timing of treatment

Durante el proceso normal del crecimiento y desarrollo las dimensiones de los arcos cambian; esto deberá ser considerado en la planificación del tratamiento. La disminución de la longitud de los arcos en ambos maxilares aparece como resultado de la migración de los dientes en los segmentos bucales (el componente anterior de fuerzas presente durante la masticación y otras funciones sugiere que una de las probables causas sea este corrimiento mesial). Comenzando el tratamiento en la dentición mixta tardía será posible controlar razonablemente bien los cambios ánteroposteriores en el sector incisivo mandibular, aún con requerimientos de espacio considerables. Un dispositivo para mantener el perímetro del arco inferior, colocado antes de la exfoliación de los segundos molares primarios, podrá prevenir la mesialización de los primeros molares permanentes. La utilización del espacio "E" ayudará a minimizar o resolver el apiñamiento anteroinferior presente (AU)

The not-so-harmless maxillary primary first molar extraction.

BACKGROUND: Premature loss of primary molars has been associated with space loss and eruptive difficulties, especially when the loss occurs to the primary second molars and when it occurs early. This has not been thought to be the case for primary first molars. METHODS: The author revisited 13 cases from an earlier study on the effects of premature loss of maxillary primary molars. These longitudinal cases were scrutinized, using serial panoramic radiographs, to explain the irregular response in terms of dental migration. The author presents two case reports. RESULTS: In the earlier study, the author used digitized study casts and the concept of D + E space--the space occupied by the primary first and second molars--to describe the dental migration that occurred after premature tooth loss. Using analysis of variance on data generated using an instrument capable of measuring in tenths of millimeters, the author produced findings regarding the amount of space loss, rate of space loss, effect of age at loss, amount of space regained at the time of replacement by the permanent tooth and effect on Angle's classification. Finally, the author created a simulation describing directional change; this revealed that the maxillary primary first molar loss resulted in a mesial displacement of the permanent canine during eruption. CONCLUSIONS: When the maxillary primary first molar is lost prematurely, the first premolar erupts in a more mesial direction than normal, as a result of the mesial incline of the primary second molar, and consumes the space of the permanent canine, which becomes blocked out. CLINICAL IMPLICATIONS: Rather than use a space maintainer after the premature loss of the maxillary primary first molar, the author suggests, clinicians can choose from a number of other options for preventing the first premolar from erupting too far in a mesial direction.

Lower arch perimeter preservation using the lingual arch.

The purpose of this investigation was to determine whether the placement of a mandibular lingual arch maintained arch perimeter in the transition from the mixed to the permanent dentition, and if so, whether it was effective at preventing mesial migration of first permanent molars, or whether this migration still occurred en masse, by increased lower incisor proclination. Thirty patients were randomly assigned to either a treatment group (N = 14, mean age = 11.5 years) or a control group (N = 16, mean age = 11.3 years). Study models, cephalograms, and tomograms of the patients, taken at the beginning and at the end of the study period, were examined. Statistically significant differences between groups were found for positional changes of mandibular first molars and incisors, and changes in arch dimensions. The results indicate that the lingual arch can help reduce arch perimeter loss, but at the expense of slight mandibular incisor proclination.

Third molars and incisor crowding: when removal is unwarranted.

Recent evidence indicates that extracting unerupted mandibular third molars neither decreases interdental force measurably nor prevents mandibular incisor crowding. There are valid reasons for extracting third molars. But extraction for the exclusive purpose of relieving interdental pressure and thereby preventing incisor crowding is unwarranted.

Response to activator treatment in Class II malocclusions.

A clinical study was designed to disclose the effects of activator treatment in the correction of Class II malocclusions. The rationale for the use of the activator appliance was based on the premise that correction of distocclusion can be achieved by inhibition of forward growth of the maxilla, inhibition of mesial migration of maxillary teeth, inhibition of maxillary alveolar height increase and extrusion of mandibular molars, increased growth of the mandible, anterior relocation of the glenoid fossa, mesial movement of mandibular teeth, and combinations of these effects. The appliance, as designed for this study, could potentially have an effect on all of these factors. Measurements were obtained from cephalometric head films obtained at 6-month intervals. Matched-pairs analyses of control versus treatment change after 6 months and after 1 year of treatment were done on 36 and 29 pairs, respectively. Pretreatment versus treatment changes were analyzed on 33 subjects by means of the spline regression analysis; posttreatment versus treatment changes were analyzed on 18 subjects by means of the Student Newman-Keuls multiple comparison test. The matched-pairs analyses of mean values demonstrated significant reduction in forward growth of the maxilla, uprighting of the maxillary incisors, reduced overjet, leveling of the mandibular occlusal plane, improved molar relationship, downward and forward relocation of the glenoid fossae, increased advancement of all mandibular structures, increased face profile angle, and increased lower face height. The two longitudinal analyses yielded similar findings, but some differences were noted. Because rather severe dental malocclusions were corrected, the slight average inhibition of maxillary growth and the anterior relocation of glenoid fossae alone could not account for the correction of the Class II dental arch relationship. It was therefore concluded that, in addition to the statistically significant changes, smaller changes occurred in several areas without being consistent enough or of a large enough magnitude to become statistically significant in the analyses of mean values. Comparison of group averages may mask treatment effects that significantly contribute to the correction of malocclusions in individual cases.