SKELETAL AND DENTAL EFFECTS ON PATIENTS WITH SKELETAL CLASS II DUE TO MANDIBULAR CHIN RECEDING, TREATED WITH ORTHOPEDICAL APPLIANCE HERBST Systematical Revision Bonilla, J., Carvajal W., Cuartas L., Espinosa A. Moncayo C. 1 INTRODUCTION Perdomo Andres Felipe 2 Bastidas Claudia 3 Class II division 1 malocclusions with a mandible deficiency are frequent in Central Europe societies. 1 Facial aesthetics plays an important role in the objective and subjective perceptions of beauty. Therefore, the improved aesthetics resulting in less convex and straighter profiles is an objective of the treatment when managing such cases. The improvement resulting in the aesthetics is considered an important reason for the indication of orthodontic treatments in these cases. 2 From the multitude of functional appliances used for correcting malocclusion Class II, the Herbst appliance is one of the indicated ones. The Herbst appliance due to the fact of being fixed compared to the removable appliances 31, is particularly advantageous because patient s compliance is not a problem. However, a disadvantage of the Herbst appliance is its propensity to breakage. 3 The original Herbst appliance consisted of bands linked to the teeth as anchorage 4, but McNamara and Brudon 5 proposed a version united to an acrylic ferula. The theoretical advantage of version with ferula would be that the acrylic coverage would include several teeth, potentially controlling the amount of proclination of the incisors during the treatment. This has been reported as a disadvantage of the welded Herbst appliance. 6 Due to the above the researchers propose the following research question: what are the skeletal and dental changes that assist in the correction of the class II skeletal malocclusion due to mandible receding opisthognathism, resulting from the use of the Herbst orthopedic appliance, reported in the scientific literature? Few systematic revisions have been made in the field of orthodontics, 7 although some revisions 8,9 have analyzed the skeletal and dental effects of the Herbst appliance, just one revision 6 has only and not simultaneously analyzed the united type Herbst appliance compared to other functional appliances. This systematic
revision had the purpose of assessing the skeletal and dental changes in the treatment of malocclusion Class II division 1 with the use of Herbst appliance, analyzed with lateral cephalograms and that used the cephalometry proposed by Dr. Hans Pancherz, 26 and more specifically the objectives of this bibliographical revision are the following: Determining the dental changes resulting from the use of the Herbst orthopedic appliance reported on the orthodontic literature. Determining the skeletal changes resulting from the use of the orthopedic Herbst appliance reported by the orthodontic literature, and finally Determining the percentage of skeletal vs. dental changes in the total change of the solution of class II with the use of the Herbst orthopedic appliance. MATERIALS AND METHODS A computerized search was directed using Medline (from 1966 to the week 3 in January 2006), Pubmed (from 1966 to the week e in January 2006), Embase (1988 to the week 4 in 2006), Best Evidence (from 1991 to the week 4 in 2006), Science Direct (1998 2006). The conditions used in this search of the literature were Herbst and functional appliances. The selection and the specific use of each term with its respective cross (Table 1) The following inclusion criterion was used for the selection of the summaries to be used for selecting the articles of potential revisions: Human clinical assays; The use of Herbst appliance for treating malocclusion Class II division 1. No syndromic patient or simultaneous surgical or orthodontic intervention; No report of individual case or series of cases; Skeletal and/or dental changes assessed through lateral cephalograms. As it was considered not probable that all or most of the abstracts would provide sufficient information regarding the use of control groups in their studies and the use of modified cephalometric analysis proposed by Dr. Hans Pancherz 26 (Fig. 1), no effort was made in this stage for identifying the studies that did not use suitable control groups for factorizing the changes in growth. All the abstracts that seemed to fulfill the initial inclusion criterion were selected. Those abstracts that did not provide sufficient information for determining their validity within the inclusion criterion were selected for the purpose of making the last decision with the full article. The articles were finally selected and such selection was only made after the full article was read and chosen using the following additional inclusion criterion: An untreated comparable control group Class II division 1;
Only the measures proposed by Dr. Hans Pnacherz, 26 modified cephalometric analysis (Table II, Fig. 1). The use of this cephalometry was determined as it was designed by Dr. Hans Pancherz who introduced the appliance during the eighties and has published the higher number of articles on this issue in the orthodontic literature. Database Result Pubmed (1966 2006) 986 Medline (1966-2006) 198 Best Evidence (1991-2006) 1 Embase (1998-2006) 7 Science Direct (1998-2006) 62 Table I: Result of the search through different databases. The full articles chosen from the abstracts of the selected articles were then independently assessed for each author. A unanimous general agreement was reached regarding which articles fulfilled the selection final criterion to be included in the systematic revision. It was considered that the cranial-facial growth was a very important problem that deserved to be factorized. Such factorization was required for making an accurate appraisal of the number and the real magnitude of the changes. The failure in considering and explaining the cranial-facial changes could result in a potential over-estimation of the amount of change attained. The reference lists of the retrieved articles were also hand searched for seeking the additional pertinent publications that could have been missed during the scrutiny of the databases. Figure 1. Pancherz Modified Analysis. Reference cephalometritos point. OL: Occlusal line OLp: Perpendicular to occlusal line A: A point or also called sub-spinal SS point Pg: Pogonio Ar: Articular Ms: First maxilar permanent molar mesial surface Mi: Mesial surface of the first mandible permanent molar Is: Cuspal apex of the upper central incisive teeth li: Cuspal apex of lower central incisive teeth
The inclusion factor of the use of the Pancherz cephalometry uses 12 variables that allowed making a recompilation of the information in an unanimous manner, which were used for working (Table II). is/olp minus ii/olp Overjet 1 Ms/OLp minus M/OLp molar relation (positive value indicates distal 2 relation; negative value indicates normal or mesial relation) 3 A/OLp position of maxillary base 4 Pg/OLp position of mandibular base 5 Is/OLp position of maxillary central incisive teeth 6 ii/olp position of mandibular central incisive teeth 7 Mi/OLp position of first mandibular molar 8 Is/OLp (D) minus changes in the position of maxillary incisive 9 A/OLp with the maxillary Ii/OLp (D) minus the changes in the position in the mandibular 10 Pg/OLp (D) incisive teeth with the mandible Ms/OLp (D) minus the changes in the position of the first 11 A/OLp (D) permanent maxillary molar with the maxillary M/OLp (D) changes in the position of first molar 12 Pg/OLp (D) permanent mandibular with the mandible Table II: Variables in the analysis of Pancherz modified cephalometry RESULTS The results of the search and the final number of selected abstracts, in accordance with the initial selection criterion of several databases are provided in Table I. Of the initially revised abstract, 18 studies fulfilled the criterion for the initial inclusion, but during the revision and after reading the articles, only five 26-30 articles met the selection final criterion (27%). Of the 18 initial abstracts, five studies 8-12 were rejected because they included control groups that not all were Class II, division 1 cases, five 18-22 articles, due to the fact that they used cephalometries different from the one proposed by Pancherz, two articles 23-24, because their results did not show all the variables of the cephalometry, and one article, because it did not report any control group 25, some articles were rejected due to more than one reason. Of the five (5) 26-30 articles finally selected, the total number of patients studied was 137 of whom 78 are women and 59 are men (Fig. 2) with an average age of
14.5 years and a range of 11.4 to 44.4 years, who were subjected to a sagital occlusion or class 1 overcorrection during an average term of 7 months. Sample distribution per gender Figure 2. Gender distribution of the total number of individuals analyzed in the five analyzed articles. The overjet average correction was 10.04 mm, of which 7.11 mm that correspond 70.79% are dental changes and 2.93 mm that correspond, 29.21% are of skeletal changes (Fig. IV). The change in the dental overjet specifically had changes in a range from 4.11 mm (sample average age 21.9 years). The lower incisive teeth contribute the higher change for the correction, 5.29 mm average equivalent to 52.71% with a range from 3.96 mm to 6.67 mm, and the higher value belongs to an adult patient (21.9 years). The skeletal changes that contribute to the overjet correction are basically mandibular changes with an average value of 2.59 mm (25.81%) and which higher values are in the group of patients in growing stage or at the end of such stage (12.01 to 16.5 years). In the same way, the molar correction that was 9.32 mm had a dental component of 6.39 mm (68.53%) and a skeletal component of 2.93 mm (31.47%), (Fig. 5). The dental component specifically occurs more frequently due to changes at the level of the lower molars that become mesial 4.55 mm, equivalent to 48.82% in average and which ranges are 2.67 mm to 6.45 mm, while the upper molars become distal in 1.84 mm average (19.71%) with ranges from 0.78 mm to 2.55 mm (Fig. 3). Within the skeletal component, the higher contribution is given by the changes in the position of the mandibular base with an average advancement of 2.59 mm, equivalent to 27.80% (Table III, Fig. 6). Table III. Tabulation of the 12 variables of the Pancherz modified cephalometry of the 5 selected articles, and their average value. The numerical order of the articles 26-30 corresponds to their chronological order. Some studies 37 made with the Herbst appliance have demonstrated that this appliance only has a temporary impact on the existing skeletal growing pattern. During a post-treatment period of 7 years, several of the treatment changes tend to disappear and the increase of the anteroinferior facial height seen during the treatment also tend to decrease along time. Figure 3. Diagram of maxillary and mandibular and dentoalveolar skeletal changes in the contribution to overjet sagital correction and molar relation during the treatment, total values.
Some changes are reported in the position of maxillary base, but these probably are not significant changes (0.09 to 0.58 mm, 0.34 mm average). The changes reported in the position of the maxillary central incisive teeth average 1.82 mm that are really insignificant, as well as the changes reported in respect of the position of the first permanent maxillary molar that averaged 1.84 mm. The sex differences were not calculated because the number of men is 60% lower in the articles corresponding to 3 articles 26,27,29 Figure 4. Scheme of the skeletal change participation - 31% vs. dental 69% in the correction of Molar relation STATISTICAL ANALYSIS For each variable we obtained the mean, the mean quadratic mean, and the maximum and minimum values were calculated. The statistical significance was determined by the probability levels of 0.1, 1 and 5 percent. A probability level higher than 5% was not considered significant. Figure 5. Scheme of skeletal change participation 29% vs. dental 71% in Overjet correction Component of skeletal change Articles Maxillary Mandibular Figure 6. Graphic of skeletal component in class II correction, maxillary participation per article and total DISCUSSION This systematic revision was made with the purpose of recompiling and analyzing the skeletal and dentoalveolar changes occurring in individuals that present malocclusion Class II and who were treated with the Herbst orthopedic appliance. The studies in general agreed as for their direction and some in the magnitude of their results regarding skeletal and dentoalveolar changes. The selected studies showed that the dental component is the one that contributes the most to the correction of malocclusion Class II Division 1 when the Herbst orthopedic appliance is used, specifically the lower teeth that present proclination of the incisive one with a value higher than 6.67 mm reported in a study made by
Dr. Sabine Ruf and Dr. Hans Pancherz in 2006, and mesial movement of the molars with a value higher than 6.45 reported by the same authors in 1999. A major overjet correction was obtained in the group reported by Dr. Lorenzo Franchi, Tiziano Baccti and McNamara in 1999, performed on patients with an age average of 12 years and 10 months and who were in a development active period that was determined through the use of the development stages of the cervical vertebrae as an indicator of the skeletal maturity, contrary to the results obtained in the group of patients of Dr. Sabine Ruf and Dr. Hans Pancherz in 2006, which age average was 21.9 years and who had already completed their skeletal maturity. No significant change was reported for the upper incisive teeth, but it was indeed reported for the upper molars that present distalization. Similar trends were identified in most of the studies excluded in the second stage of the search and selection process. All the dental changes presented in general are the result of anchorage loss as reported by Dr. Pancherz in 1982 and corroborated by a study published by Dominique Weschier and Hans Pancherz himself in the Angle of Orthodontics in 2004 34, and which also conclude that none of the three forms of mandibular anchorage used in Herbst treatment can prevent anchorage loss. There is not difference between men and women due to women predominance in 60% of the articles, and this is very probably due to the interest they the women have in seeking the improvement of their facial and dental appearance. In three 27,29,30 of the selected studies we found that they reported recidivation in the patients treated during the post-treatment period, and attributed to dental changes and specifically in upper molars. Within the important flaws found in the selected articles and in general in studies that deal with Herbst appliances, we found that there is not homogeneity as for gender, which does not allow the study to conclude if differences exist between the females and males. Another flaw noted during the recompilation process by this systematic revision was the limited number of studies that fulfill our selection criterion. For supporting the conclusions, long term, legitimate, probability, blind, randomized clinical assays are methodologically needed. A difficulty found during this systematic revision is that typically each article used variables and reference points different in their cephalometric analyses, and this is why we determined to include as a selection criterion that the article used the Dr. Pancherz (1982) sagital cephalometric analysis, for being able to have biometric measurements that could be compared.
CONCLUSIONS All the selected studies showed that the use of Herbst appliance when treating patients with malocclusion Class II produced major dental changes in lower maxillary as proclination of the incisive teeth and mesial movement of the molars. Better skeletal results are obtained when the Herbst appliance is used in patients who are in active growth periods, than when such appliance is used in adult patients in whom the result is due more to dental changes than to skeletal changes. The dental changes produced by the use of the appliance are translated into anchorage loss, which could be diminished when changing the form of dental fixation to a skeletal fixation by means of implants. RECOMMENDATIONS Carry out more studies including in their sample an equal number of men and women for being able to differentiate the changes between the sexes. Study in a larger group of adult people, the changes resulting from the use of Herbst appliance, and therefore being able to establish if this treatment can be a reliable and long term alternative to the one achieved by the surgical treatment.