Dental arch width in unoperated cleft patients
A scientific essay in Medical Sciences
DOCTORAL THESIS defended in public on 20th of January 2005
Chapter 1 gives a review of the literature from the pioneer era of surgeons who have aimed to treat cleft lip and palate up to the present day. In the early days the treatment consisted of surgical lip closure only. Following the introduction of general anaesthesia, surgeons have been able to develop techniques to close the palatal cleft also. Nowadays many techniques or variations of existing techniques are proposed both for lip surgery and for palatal closure. The main disadvantage of these techniques, especially those for closure of the palatal defect, is that patients, who had palatal surgery in early childhood, gradually develop a growth disturbance of the maxilla and often a vast lateral compression of the dento-alveolar part of the maxilla. It is not clear whether these growth disturbances may be attributed to the congenital malformation itself, to the cleft surgery, or to both. In an attempt to answer these questions, a study was performed on dental casts of unoperated adult cleft patients. The aims of this study were firstly to evaluate the final transversal development of the dental arches and the palatal vault in 4 main categories of cleft patients without the influences of previous surgical treatment and secondly, in the event of developmental disturbances being found, to define the extent and location of the disturbances.
Chapter 2 describes the subjects and methods being used in this study. Between 1986 and 1997 9 expeditions were undertaken in remote areas of Indonesia and almost 2400 patients were operated of whom 267 patients, who were considered to be unoperated adults, have participated in the present study. The patients were divided into 4 groups of clefts: unilateral cleft lip and alveolus (UCLA), bilateral cleft lip and alveolus (BCLA), unilateral cleft lip, alveolus and palate (UCLP), and bilateral cleft lip, alveolus and palate (BCLP). From these patients maxillary and mandibular impressions were made and dental casts were fabricated. Dental casts of 24 non-cleft individuals, selected at random from the surrounding population, were used as a control group. The dental casts of the cleft and non-cleft group were digitized three-dimensionally, using an industrial coordinate measuring machine. Means and standard deviations were calculated for transverse dimensions of the upper and lower jaw, palatal shelf width and palatal shelf angle. The t-test was conducted to determine whether the mean values of the cleft groups showed significant differences from each other and from the control group. The level of significance was set at p<0.05.
Chapter 3 is dealing with the study of dental arch width of the mandible in four types of unoperated clefts. Earlier studies on cleft patients mainly focussed on the transversal dimensions of the maxilla. Only a few reports can be found in the literature that have investigated the mandibular width of cleft patients, although it is well-known that compensatory dental and skeletal changes can occur in one jaw as a result of changes in the other one. The aim of this study has been to investigate whether the mandibular dental arch width of unoperated adult cleft patients differs from adult non-cleft individuals of the same population. The material consisted of dental casts of adult unoperated cleft patients divided into 4 groups: UCLA (n=168), UCLP (n=68), BCLA (n=18), and BCLP (n=13). Dental casts of 24 non-cleft individuals from the same population were available as a control group. It was found that in cleft types where the palate is not involved (UCLA and BCLA), the mandibular transversal dimensions were essentially normal. However, in complete UCLP, where the palate is involved, the mandibular transversal dimensions were wider than in the control group. For BCLP this was not found, probably due to the small sample size of this type of cleft. Whether this widening of the lower dental arch is related to a wider maxillary dental arch in complete unoperated clefts needs to be investigated further.
In chapter 4 the transversal maxillary arch dimensions of two types of unilateral clefts in untreated adult individuals are compared to each other and to a control group of the same population. The material consisted of dental casts of adult unoperated cleft patients divided into two groups: UCLA (n=168) and UCLP (n=68). Dental casts of 24 non-cleft control subjects were available from the same population. The dental casts were digitized three-dimensionally using an industrial coordinate measuring machine. Maxillary transversal dimensions were calculated, using the cusps of the teeth as reference points. The dental cast analysis revealed that the maxillary arch dimensions in UCLA were essentially normal except for the intercanine distance. This was also expressed by the upper arch ratio showing that in UCLA the mean intercanine width is 60.4% of the intermolar width, while in the control group this value is 64.2% (p=0.00005). In the UCLP group the maxillary width at the level of the second molar was significantly larger compared to the control group. The mean difference for the 171-271 distance (distobuccal cusps) was 3.3 mm (SE 0.8) and for the 172-272 distance (mesiobuccal cusps) 1.8 mm (SE 0.7). Consequently, there is a mesio-palatal rotation of the second molar. The arch width at the level of the first molar and second premolar was not statistically different in comparison with the controls. Between the first premolars, the maxillary width of the UCLP group was 2.1 mm (SE 0.6) smaller compared to the control group (p=0.0008). At the level of the canine this difference was even more obvious and came up to 6.1 mm (SE 0.6) (p=0.00005). The upper arch ratio shows that in UCLP the mean intercanine width is only 53.1% of the intermolar width. In conclusion, the presence of a cleft has an influence on the final development of the dento-alveolar part of the maxilla: the more extensive the cleft, the bigger the effect on the dental arch. However, the effect is limited to the vicinity of the cleft in the anterior region only. These findings support the hypothesis that in treated cleft palate patients developmental disturbances of the maxillary arch are primarily due to surgery. However, the findings also suggest that each type of cleft has its own intrinsic characteristic dental arch form. Surgical procedures might influence subsequent growth, which makes the intrinsic deviation clinically manifest.
In chapter 5 a study is described on maxillary dental arch width of unoperated adult subjects with a bilateral cleft lip and alveolus (BCLA) and a bilateral cleft lip, alveolus and palate (BCLP). The sample consisted of 18 unoperated BCLA subjects and 13 unoperated BCLP subjects. A non-cleft sample (n=24) from the surrounding population served as controls. Alginate impressions of the participating subjects were made and the dental casts were digitized three-dimensionally, using an industrial coordinate measuring machine. Maxillary transversal dimensions were calculated, using the cusps of the teeth as reference points. The results show that the transversal maxillary arch dimensions in the BCLA group were comparable to the controls. Only at the canine level a significant difference was found. The intercanine distance, which is close to the alveolar cleft, was 4.3 mm (SE 1.4) smaller in the BCLA-group in comparison with the control group (p=0.002). This was also expressed by the upper arch ratio showing that in BCLA the mean intercanine width is 56.8% of the intermolar width, while this value is 64.2% (p=0.0009) in the control group. In BCLP a comparable pattern was found. At the canine level the mean transversal width was even 7.2 mm (SE 1.9) smaller in comparison with the control group (p=0.0003), while all other transversal dimensions were not significantly different from the controls. The upper arch ratio was 51.8% in the BCLP group and 64.2% in the control group and this difference was significant (p=0.0004). We may conclude that the cleft as a congenital malformation has an intrinsic, although limited effect on the dento-alveolar development of the maxilla and only in the canine region. These results are important for our understanding of the iatrogenic effects of the surgical repair of the lip and/or palate, which might eventually lead to the development of more appropriate surgical techniques and better orthodontic management.
Chapter 6 deals with the question whether the width of the palatal cleft is determined by real shortage of tissue in the palatal area or whether the width of the cleft is related to malposition of the palatal shelves, or a combination of both factors. Therefore the purpose of this study has been to investigate the width and elevation of the palatal shelves in unoperated adult UCLP and BCLP in comparison with a non-cleft control group. The width and elevation of the palatal shelves were measured on dental casts of 81 fully unoperated patients from Indonesia of whom 68 had a complete UCLP and 13 a complete BCLP, and compared to a control non-cleft sample (n=24) of the same population. In unoperated UCLP patients the width of the palatal shelves at the cleft side was significantly smaller in comparison with the control group. The same holds good for the non-cleft side, except in the canine / first premolar region. The unoperated BCLP subjects showed the same pattern although the difference with the controls was not significant for every dimension. In comparison with the control group the angle of the palatal shelves in the UCLP subjects was larger, which means that the palatal shelves are rotated cranially and are more vertically positioned. Also in BCLP the angle of the palatal shelves was almost 10 degrees more than compared to the control group. The palatal shelf elevation was not significantly different between the two cleft groups. It was concluded that the width of the palatal cleft is determined by a smaller palatal shelf width and a larger elevation of the shelves resulting in a wider cleft. Therefore surgical techniques should be developed that take into account the intrinsic deviations, which might result in better dentomaxillary development.
In chapter 7 the results as reported in this thesis, are discussed. From the findings it can be concluded that there is an intrinsic or functional effect of the cleft itself on dentofacial development of the maxilla and to a lesser extend on the mandible. Each type of cleft has its own intrinsic characteristic dental arch form. However, compression of the maxilla is limited to the vicinity of the cleft in the anterior region. When the palate is involved, the palatal shelves seem also to be deficient and positioned more cranially. These findings support the hypothesis that surgery might influence subsequent maxillary growth, which makes the intrinsic deviation that is already present, clinically manifest. There is a continued need to investigate the effects of different surgical procedures on maxillofacial growth and dento-alveolar development. Supplemental to that, the study of unrepaired clefts could teach us more about the natural history of clefts. Special attention should be given to bilateral cleft conditions as very few studies with a sufficient sample size have been published, neither about repaired nor about unrepaired clefts. Short-term and long-term follow-up of adult patients operated after facial growth had ceased, could provide more insight into the effect of surgery itself excluding growth as a confounding factor. It is obvious that careful attention should be given to the anatomical deviating palatal shelves and the consequences for the surgical reconstruction of the palate in order to modify present surgical techniques for achieving better long-term dentofacial development in patients with clefts.