Bilateral cleft lip and palate. Maxillo-facial growth and dental development.
A scientific essay in Medical Sciences
DOCTORAL THESIS defended in public on 17th of November 1997
In the introduction in chapter 1 the bilateral cleft lip and palate malformation and the problems which are attached to it are explained.
In chapter 2 the development of maxillary arch dimensions in 26 BCLP boys is described during the first four years of age. Palatal arch dimensions were studied on dental casts and compared with 34 non-cleft boys. In this study it was found that at birth arch widths as well as arch depths were significantly larger in BCLP. After seven months, time of lip closure, anterior arch width and arch depth diminished considerably in the cleft group. After 12 months of age, time of palatoplasty, a slight decrease of posterior arch width was observed. Arch depths showed a slight catch-up growth. At four years of age, anterior arch width was significantly narrower and anterior arch depth significantly shorter in BCLP as compared to the controls. Posterior arch width became significantly wider than at the earlier stage. A significant midline deviation was apparent over the whole investigated period.
Chapter 3 analyses the effects of early orthopaedic and/or surgical treatment on maxillary alveolar arch development in 30 children with a complete bilateral cleft lip and palate. Palatal arch dimensions were measured on dental casts and their growth velocities during different treatment periods were calculated. Differences in growth velocities between consecutive treatment periods were examined and compared with those of non-cleft children. Prior to surgical lip closure the increase of the intercanine width of children with a BCLP and non-cleft children was comparable. Only for arch depths significantly less growth was observed in comparison with the control group. After lip closure intercanine width, arch depths and segmental angle diminished. During the intersurgical period arch form seemed to adapt to a new muscular balance. Immediately after soft palate surgery and after finishing presurgical orthopaedics, growth of the intercanine width and intertuberosity width was restricted. This negative growth was compensated in the post-surgical period, were even a catch-up growth of intertuberosity width was observed.
In the study of chapter 4 the dental age in 74 children with a bilateral cleft lip and palate was assessed and compared to 181 Dutch children without a cleft at three different ages, namely, 5, 9.5 and 14 years of age. At five years of age a significant difference in dental age was found between BCLP and non-cleft boys. At the ages of 9.5 and 14 years of age no differences were found anymore. For girls no differences in dental age were shown over the entire investigated period.
In the study of chapter 5 the effects of premaxillary osteotomy in combination with secondary bone grafting were analyzed in 22 BCLP patients by means of cephalograms and dental casts, taken before and after treatment. As a control group, BCLP patients treated by the cleft palate center, Oslo were used. Treatment planning of these two teams is comparable, except for the fact that in Oslo surgical repositioning of the premaxilla is never performed. After osteotomy, good arch form was achieved, the premaxilla was positioned more superiorly and normal inclination of incisors was achieved. It proved not to be possible, however, to lower a high-positioned premaxilla to a normal vertical relationship.
Chapter 6 describes the sagittal facial growth of bilateral cleft lip and palate patients between six and 20 years of age. The data of Nijmegen, derived from 131 lateral cephalograms taken in 21 BCLP patients, were compared with reported data of 90 BCLP patients treated at the Center of Oslo. Results of this investigation showed mandibular growth to be similar in both centers. In the premaxillary region some differences were found: The Nijmegen patients presented a more protrusive premaxilla than those at Oslo. The upper front teeth and hence, the premaxilla, were more retroclined in the Nijmegen sample. There were also statistically significant differences in the soft tissue profile. The mean Z-score was positive for the nasiolabial angle and negative for the angle N'-Sn-Pg'. At 18 years of age, these differences were still apparent. In comparison with Broadbent's values of normal individuals, the SNPg-angle was smaller and the mandibular angle greater in Nijmegen and Oslo. The profiles of the BCLP patients are more convex in Nijmegen and more concave in Oslo than in the non-cleft group.
The aim of the study of chapter 7 was to describe maxillary and mandibular dental arch form and occlusion in 22 bilateral cleft lip and palate from three to 17 years of age and to compare their characteristics with a normative sample. Dental arch dimensions were studied on dental casts. From nine years of age, the cleft sample showed a significantly smaller maxillary depth. Maxillary dental arch widths were also significantly smaller than in the control group over the whole age period. Mandibular dental arch measurements were very similar in both groups, although smaller mandibular first molar widths were noted in the BCLP group beginning at 12 years of age. A tendency for a transverse end-to end occlusion was found, which became more clear with age and was most markedly at the canine region.
In chapter 8 a discussion is given on the study as a whole and suggestions are made for further research.