*2.2.1 Cleft severity and delayed dental development*

Ranta went on further to conduct other investigations and revealed that the delay in tooth formation increased from 0.3 to 0.7 year with increasing severity of the cleft deformity. No significant difference was found in the tooth formation of subgroups with and without hypodontia [23]. However, in his later study on children with isolated CP only, he found that the dental development was delayed longer in the cleft subgroup with hypodontia (0.7 year) than in the subgroup without hypodontia (0.4 year), and a somewhat longer delay in tooth formation was observed with increasing number of missing teeth per child [24].

## *2.2.2 Age and delayed dental development*

Harris and Hullings studied 54 CLP children and reported an overall delay in dental development of 0.9 year. They also noted that teeth formed during the early postnatal period were most affected, while the later forming teeth were less delayed [19].

Other authors [25–28] found that the delay in dental development begins to decrease from the age of 8 to 9.5 years old, suggestive of some form of catch-up growth [29, 30]. This is in contrast to the findings of Ranta who noted that the delay in dental development was significantly longer in the older age group of 9 to 12 years old (1.1 years) than in the younger age group of 6–9 years old (0.6 year) [3].

A study by Borodkin et al. found an overall delay in dental development of 0.52 year, but was found to be statistically significant only in male cleft subjects [21]. The most commonly delayed permanent teeth were the maxillary first and second premolars and maxillary second molars. No statistically significant differences in dental development were found between the various cleft types and severity of cleft deformities.

**5**

*Dental Development and Anomalies in Cleft Lip and Palate*

In another investigation, Lai et al. based their study on 231 southern Chinese CLP children from Hong Kong and compared them with a non-CLP control sample of the same size [20]. Similarly, they found an overall delay in tooth formation of Chinese CLP children (0.4 year) with the earlier formed permanent teeth being more delayed in development than those formed later. In accordance to the findings of Ranta [23], CLP children with more severe hypodontia were also more delayed in

Tan et al. found that UCLP children at 5–9 years old had more delayed dental maturation of 0.55 year when compared to controls [28]. The delay in dental maturation attenuated as they grew older and no difference in dental maturation were found in the UCLP children and controls at 9–13 years old. Several postulations may account for this phenomenon. Firstly, there could be some form of catch-up growth in the patients with CLP as they mature, as described by some authors [27, 29–32]. Secondly, the accuracy and precision of Demirjian's method [9] have been shown to decrease with age [13, 26, 33]. This is because the tooth developmental stages occurring earlier in life are generally of shorter duration than the stages occurring later, and the stages of short duration are more easily discerned with distinctive changes over a shorter period than smaller increments over a longer duration [13]. In addition, at an older age, the assessment of dental age is based on fewer teeth with roots that are not fully formed. For example, at the age of eleven, there may only be two teeth (usually the second premolar and second molar) with incomplete root formation, and the assessment of dental age would be based entirely on these two teeth. Any measurement error will, thus, have a profound effect on the dental age determination. Hence, there is a tendency to overestimate the dental age in the older age group, and this could reduce the discrepancy in dental age delay between the group with UCLP and without CLP. Furthermore, the roots of the teeth in patients with CLP are reported to be shorter than average [34], and this may further complicate the assessment of dental age. Thirdly, only the incisors and first molars are affected by environmental factors during gestation and early prenatal period [35]. As the formation of these teeth plays a big part in determining the dental age in the younger age group, their effects on the length of dental age delay would be significant. Root formation of the incisors and first molars would have been already completed in the older group of subjects; hence, they no longer have an impact on the dental

Tan et al. found that the presence and extent of hypodontia in CLP patients did not influence the dental development [28]. This contrasted with earlier studies [20, 24] that found a bigger delay in dental development in clefts with hypodontia than without hypodontia, and the more severe the hypodontia, the bigger the delay. However, these studies had several confounding factors. Ranta's study only included patients with isolated cleft palate [24], while the study of Lai et al. included various

The evidence for any gender association has been weak, with some studies suggesting that the delay was more pronounced in boys compared to girls [20, 21, 27], and other studies showing no significant gender differences [18, 23, 24, 26, 28, 36].

*DOI: http://dx.doi.org/10.5772/intechopen.88310*

dental development.

age determination.

cleft types [20].

*2.2.3 Hypodontia and delayed dental development*

*2.2.4 Gender and delayed dental development*

*Current Treatment of Cleft Lip and Palate*

**2.2 Delayed dental development**

image was unclear, the contra-lateral tooth was used [9].

score value, or by using a table which had been constructed.

*2.2.1 Cleft severity and delayed dental development*

*2.2.2 Age and delayed dental development*

According to the criteria, the maturity of the seven mandibular teeth on the left side (excluding the third molar) was determined by comparing their radiographic appearances with a sequence of reference radiographs and diagrams, and description of formation stages. If any of the mandibular left teeth was missing, or its

Each tooth was divided into eight formative stages (A to H), and each stage was allocated a score depending on the gender. The scores for all seven teeth were then added to give the maturity score which can be converted directly into dental age by reading off a percentile curve the age at which the 50th centile attains the maturity

Several investigators reported on delayed formation of the permanent teeth in

Bailit and coworkers found that tooth formation in 39 children with cleft palate was significantly retarded by about 0.7 year when compared with 36 normal controls [16]. Ranta in his earlier study compared 258 CLP Finnish children with 1162 noncleft children and reported a delay in tooth formation of 0.5 year in the maxilla and 0.4 year in the mandible, but the difference was not statistically significant [18].

Ranta went on further to conduct other investigations and revealed that the delay in tooth formation increased from 0.3 to 0.7 year with increasing severity of the cleft deformity. No significant difference was found in the tooth formation of subgroups with and without hypodontia [23]. However, in his later study on children with isolated CP only, he found that the dental development was delayed longer in the cleft subgroup with hypodontia (0.7 year) than in the subgroup

without hypodontia (0.4 year), and a somewhat longer delay in tooth formation was

Harris and Hullings studied 54 CLP children and reported an overall delay in dental development of 0.9 year. They also noted that teeth formed during the early postnatal period were most affected, while the later forming teeth were less

Other authors [25–28] found that the delay in dental development begins to decrease from the age of 8 to 9.5 years old, suggestive of some form of catch-up growth [29, 30]. This is in contrast to the findings of Ranta who noted that the delay in dental development was significantly longer in the older age group of 9 to 12 years

old (1.1 years) than in the younger age group of 6–9 years old (0.6 year) [3]. A study by Borodkin et al. found an overall delay in dental development of 0.52 year, but was found to be statistically significant only in male cleft subjects [21]. The most commonly delayed permanent teeth were the maxillary first and second premolars and maxillary second molars. No statistically significant differences in dental development were found between the various cleft types and severity of

observed with increasing number of missing teeth per child [24].

CLP patients and the delay was observed to vary from 0.3 to 0.9 year [16–22].

*2.1.1 Demirjian's method*

**4**

delayed [19].

cleft deformities.

In another investigation, Lai et al. based their study on 231 southern Chinese CLP children from Hong Kong and compared them with a non-CLP control sample of the same size [20]. Similarly, they found an overall delay in tooth formation of Chinese CLP children (0.4 year) with the earlier formed permanent teeth being more delayed in development than those formed later. In accordance to the findings of Ranta [23], CLP children with more severe hypodontia were also more delayed in dental development.

Tan et al. found that UCLP children at 5–9 years old had more delayed dental maturation of 0.55 year when compared to controls [28]. The delay in dental maturation attenuated as they grew older and no difference in dental maturation were found in the UCLP children and controls at 9–13 years old. Several postulations may account for this phenomenon. Firstly, there could be some form of catch-up growth in the patients with CLP as they mature, as described by some authors [27, 29–32]. Secondly, the accuracy and precision of Demirjian's method [9] have been shown to decrease with age [13, 26, 33]. This is because the tooth developmental stages occurring earlier in life are generally of shorter duration than the stages occurring later, and the stages of short duration are more easily discerned with distinctive changes over a shorter period than smaller increments over a longer duration [13]. In addition, at an older age, the assessment of dental age is based on fewer teeth with roots that are not fully formed. For example, at the age of eleven, there may only be two teeth (usually the second premolar and second molar) with incomplete root formation, and the assessment of dental age would be based entirely on these two teeth. Any measurement error will, thus, have a profound effect on the dental age determination. Hence, there is a tendency to overestimate the dental age in the older age group, and this could reduce the discrepancy in dental age delay between the group with UCLP and without CLP. Furthermore, the roots of the teeth in patients with CLP are reported to be shorter than average [34], and this may further complicate the assessment of dental age. Thirdly, only the incisors and first molars are affected by environmental factors during gestation and early prenatal period [35]. As the formation of these teeth plays a big part in determining the dental age in the younger age group, their effects on the length of dental age delay would be significant. Root formation of the incisors and first molars would have been already completed in the older group of subjects; hence, they no longer have an impact on the dental age determination.
