Letter to the Editor

TO THE EDITOR: Kita H, Kochi S, Kamiya N, et al. Alveolar ridge notching as a predictor for secondary bone grafting in incomplete alveolar clefts. Cleft Palate Craniofac J. 2004;41:36–41. I read with interest the paper by Dr. Kita et al. (2004) dealing with the importance of predicting the need for alveolar bone grafting (ABG) in the edentulous stage of incomplete alveolar clefts. Dental development in cases of incomplete clefts has been described by a number of authors. The cases all can be related to initial disturbance and disruption of the embryonic process of dental lamina formation, most notably in the area of failed merging and fusion of the medial nasal, lateral nasal, and maxillary processes (Bøhn, 1950, 1963; Ross and Johnston, 1972; Ranta, 1986; Long, 1998). The clinical effects of these embryonic failures include missing teeth, supernumerary teeth, hypoplastic teeth, dysmorphic teeth, and impacted teeth (Bøhn, 1950, 1963; Jordan et al., 1966; Kraus et al., 1966; Ranta, 1986; Semb and Schwartz, 1997). The tooth most commonly affected is the lateral incisor. When the lateral incisor is present, it can appear on either side of the cleft in near-normal form, rudimentary form, or malformation, especially in cases in which there are supernumeraries on both sides of the cleft (Bøhn, 1950, 1963; Ross and Johnston, 1972). In recent research conducted at our institute, we found that hyperdontia of the lateral incisor is more prevalent in individuals with an isolated cleft lip (incomplete cleft with or without alveolar ridge notching) than in individuals with a complete cleft lip. This phenomenon greatly corresponds with the trend reported by Nagai et al. (1965), Berkowitz (1978), and Hansen and Mehdinia (2002), who also found the highest prevalence of supernumerary maxillary lateral incisors in isolated cleft lip cases. Hansen and Mehdinia (2002) found supernumerary lateral incisors on the cleft side in 73% of subjects with isolated cleft lip. We have found microdontia of the lateral incisors of the isolated cleft lip also, with a prevalence of 31.25%. These dental anomalies all have an impact on orthodontic and prosthetic treatment planning decisions from a functional, as well as an esthetic, point of view. These decisions include extracting the rudimentary lateral incisors of both cleft sides, preparing the lateral incisor area for dental implants or other prosthetic replacements versus closing the residual extraction space using the canine eruption process, and using conventional orthodontic treatments (Nordquist and McNeill, 1975; Verdi et al., 1991; Takahashi et al., 1997; Ramstad, 1998; Long et al., 2000). We agree with the finding of Dr. Kita et al. (2004) that most patients with alveolar ridge notching require ABG. Our criteria for ABG in such cases concur with the criteria mentioned in the article: inadequate bone width, height, and thickness to permit the eruption and maintenance of the permanent dentition. From our experience, any alveolar bone defect, even minor in incomplete cleft lip and palate, is sufficient to restrict orthodontic closure of the defect and to exclude prosthetic replacement. Therefore, the main and most important role of the ABG in incomplete clefts cases (with or without alveolar cleft notching) is related to orthodontic-prosthetic considerations. These considerations require a precise clinical, as well as a radiological, examination during adolescence, the ideal time for dental implantation and orthodontic treatment. Kearns et al. (1997) published the longest follow-up (3 years) case series of 14 dental implants to grafted cleft sites. These authors reported a 90% success rate of implants in grafted cleft alveolar ridges. Interestingly, all were late secondary grafts in the permanent dentition, and 6 of the 14 patients required augmentation grafts to provide adequate bone in the cleft site. Also noteworthy is the fact that the longer the time span between graft and implant placement, the more likely the need for augmentation. We believe that a computed tomography (CT) examination is sufficient to precisely locate the bone defect form, as mentioned by Santiago et al. (1998), particularly in incomplete alveolar clefts clinically identified by appearance. CT offers demonstrable benefits given the increased financial burden and x-ray dosage, compared with simple radiography. However, a CT examination in instances of incomplete cleft should be administered during late childhood when reevaluation of the grafted bone width, height, and thickness, as well as identification of an orthodontic-prosthetic treatment plan, is being contemplated, rather than during the edentulous stage of the newborn according to Kita et al. (2004). Under the present circumstances, the benefits can be considered as exceeding the costs and risks of CT examinations during late childhood, and most probably, this late CT examination will prevent recurrence at a later age. In conclusion, ABG for orthodontic alignment of cleft-adjacent teeth is warranted in most patients with an incomplete alveolar cleft that is clinically identified. The CT examination is recommended during the late childhood or adolescence age for precise orthodontic, as well as dental, implants and prosthetic evaluations.