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The Goslon Yardstick: a New System of Assessing Dental

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The Goslon Yardstick: a New System of Assessing Dental The Goslon Yardstick: A New System of Assessing Dental Arch Relationships in Children with Unilateral Clefts of the Lip and Palate MicHaAEL Mars, F.D.S., D. ORTH. Dennis A. PLint, F.D.S., D. ORTH. WicLiam J.B. Houston, PH.D., F.D.S. OLaAv BeraLanp, D.D.S., Dr. ODont. Gunvor Seems, D.D.S. The Goslon (Great Ormond Street, London and Oslo) Yardstick is a clinical tool that allows categorization of the dental relationships in the late mixed and or early permanent dentition stage into five discrete categories. Cases are allocated to these categories on a value judgment basis by reference to the anchor groups of the Goslon Yardstick. The categorization was sufficiently sensitive to distinguish the treatment results at different centers in this study. It is proposed that the Goslon Yardstick should facilitate cross-center studies. In order to evaluate and compare the results OBJECTIVES OF THE PRESENT STUDY of different approaches to the early management The present study was designed to categorize of the child with a cleft of the lip and palate, it malocclusions in patients with unilateral clefts is essential to have a reliable method of assess- of lip and palate in a way that would represent ing dental arch relationships. the severity of the malocclusion and the difficulty Conventional methods of scoring arch relation- of correcting it. The method had to be simple ships and dental irregularities have a number of to use and highly reliable even when used by deficiencies, even when applied to routine or- different observers. The classification was to be thodontic problems, and they are not directly ap- used to compare the long-term results of differ- plicable to malocclusions in children with clefts ent approaches to the early treatment of children of the lip and palate. Several classifications have with clefts of lip and palate (e.g., the effective- been designed specifically for this purpose. ness of presurgical orthopaedic treatment and of Pruzansky and Aduss (1964) and Matthews et al different surgical procedures). (1970) proposed methods based essentially on the The stages in the investigation that are presence and extent of crossbites, but these did described here are: not account for a number of clinically important variables, such as open bites. In addition, relia- 1. Development of the yardstick bility is often low. Huddart and Bodenham 2. Application of the yardstick (1972) described a system in which a score was 3. Testing the yardstick allocated to each upper tooth according to its oc- 4, Comparison of different groups using the clusion with the lower arch. This was an im- yardstick. provement on previous methods, but as with all The initial study has been confined to children such scoring systems, it is possible that the over- with unilateral clefts of the lip and palate, and all score does not accurately represent the severi- these are at the early permanent dentition stage ty of the malocclusion: mild generalized because this is the age at which skeletal and oc- irregularity may yield a higher score than a more clusal problems are clearly manifest and at which severe but localized anomaly. definitive orthodontic and surgical treatment are usually planned. Drs. Mars and Plint are Counsultant Orthodontists at the Hospital for Sick Children, Great Ormond Street, London England. Dr. Houston is Professor of Orthodontics at Unit- ed Medical and Dental Schools of Guy's Hospital, London DEVELOPMENT OF THE YARDSTICK England. Dr. Semb is with the Department of Othodontics Three of the authors proposed the clinical fea- and is affiliated with the University of Oslo, Norway. The late Dr. Bergland was Professor of Orthodontics, and he too tures that they considered most important in was affiliated with the University of Oslo. characterizing malocclusions in the early perma- 314 Mars et al, THE GoOsLON YARDsSTICK 315 nent dentition stages of children with unilateral and were chosen to represent the full range of clefts of lip and palate. These were as follows: results. The patients had not at that stage received orthodontic treatment except for correction of 1. Anteroposterior Arch Relationships. Severe reverse overjets in the early mixed dentition. Class III incisor relationships were obvious- The models were ranked subjectively by four ly least satisfactory, and in general it was felt experienced orthodontists working independently that a Class II division 1 relationship in the and without further consultation after the initial early permanent dentition, though rare, was discussion of the criteria outlined above. The most favorable for subsequent orthodontic ranking was repeated after an interval of one correction. Preexisting dentoalveolar compen- week and the reliability was measured by Spear- sation in the presence of a reverse overjet was man's rank correlation coefficient (Table 1). Bias: not considered to be favorable, since it limits was tested using the Wilcoxon matched-pairs the possible orthodontic correction of the in- signed rank test. Intra- and interexaminer agree- cisor malrelationship; thus, it was included in ment was high, indicating a satisfactory degree the evaluation. of reliability. 2. Vertical Labial Segment Relationships. A After the models had been ranked, it became deep overbite was preferable to a reduced apparent that the cases could readily be separat- overbite which, in turn, was considered a bet- ed into five groups, which then formed the ba- ter situation than an open bite. Since over- sis of the Yardstick. Since the intention at this closure tends to exaggerate the Class III stage was to produce clear examples of the differ- tendency, it is included in the anteroposteri- ent groups, it was decided to exclude eight bor- or assessment. derline cases, leaving 22 cases as the Goslon 3. Transverse Relationships. Canine crossbites Yardstick. s of the smaller segment were considered worse These were distributed as follows: than molar crossbites, which might be clini- cally acceptable. The degree of transverse Group 1-excellent - 2 cases arch narrowness, rather than the number of Group 2-good - 7 cases teeth in crossbite, is the critical factor. Group 3-fair - 3 cases Group 4-poor - 4 cases Group 5-very poor - 6 cases Anteroposterior relationships were considered to be of greatest clinical importance, and gener- In general terms, groups 1 and 2 have occlu- alized crowding and irregularity were agreed to sions that require either straightforward or- be relatively unimportant. The yardstick was to thodontic treatment or none at all. Group 3 be based clinically on the features that pose the require complex orthodontic treatment to correct greatest difficulties in treatment. the Class III malocclusion and possibly other In order to test the application of these sub- arch malrelationships, but a good result can be jective criteria, it was decided to investigate the anticipated. Cases in group 4 are at the limits of extent of agreement between different orthodon- orthodontic treatment without orthognathic sur- tists in ordering a series of study models of 30 gery to correct skeletal malrelationships, and if cases in the early permanent dentition. These facial growth is unfavorable, orthognathic sur- were selected from the files at The Hospital for gery will be required. Cases in group 5 require Sick Children at Great Ormond Street, London orthognathic surgery to correct skeletal malrela- TABLE 1 Reliability Between and Within Examiners: Baseline Study Examiner Examiner DP MM MC JK Spearman Rank Correlation (r.) DP 0.94 MM 0.95 0.94 MC 0.94 0.95 0.96 JK 0.97 0.96 0.98 0.97 Wilcoxon Signed Ranks Test (Wilcoxon T/Number of non-zero differences)* DP 108.5/54 MM 187.0/73 123.0/;, MC 159.0/;,, 221.0/49 179.0/;,, JK 169.0735 170.0/;,, 183.0/;,7 174.0/34 * P>0.30 for all comparisons. 316 Cleft Palate Journal, October 1987, Vol. 24 No. 4 tionships if there is to be any prospect of obtain- in Figures 1-5; these records are of patients with ing satisfactory occlusal relationships. the teeth held lightly in occlusion but without Representative models from these groups, overclosure. The cases used to derive the Yard- together with the corresponding facial photo- stick are used only for reference and are not in- graphs and lateral skull radiographs are shown cluded in the subsequent analyses reported here. FIGURE 1 A representative case from Goslon Group 1 Mars et al, THE GOSLON YARDSTICK 317 FIGURE 2 A representative case from Goslon Group 2 318 Cleft Palate Journal, October 1987, Vol. 24 No. 4 FIGURE 3 A representative case from Goslon Group 3 Mars et al, tHE costoNn varpstick 319 FIGURE 4 A representative case from Goslon Group 4 320 Cleft Palate Journal, October 1987, Vol. 24 No. 4 FIGURE 5 A representative case from Goslon Group 5 Mars et al, THE GOSLON YARDSTICK 321 The Yardstick can be applied reliably only by group 3. On the other hand, a case provisional- those trained in its use with the original cases ly grouped a 3 but with an anterior openbite and who have undertaken the categorization of would probably be transferred to group 4 at this a calibration series. k stage. APPLICATION OF THE YARDSTICK Stage 3: Transverse Assessment The instructions given to the assessor are as A normal transverse relationship or a cross- follows: . bite that can be treated orthodontically does not indicate a change of group. Marked narrowing Stage 1: Anteroposterior Assessment of the upper arch with bilateral crossbite could indicate a more severe category for a case al- The overjet is examined first. If for example ready at the upper limits of a group for other there is a reverse overjet of 3 to 5 mm, this in- reasons. dicates that the case might belong to group 4.
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