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Page 2 of 10 Guagnano et al. Plast Aesthet Res 2020;7:37 I http://dx.doi.org/10.20517/2347-9264.2020.21

Keywords: Caries, cleft lip/palate, dental anomalies, hypoplasia, surgery

INTRODUCTION
Oro-facial clefts are a heterogeneous group of congenital malformations that recognise similar anomalies in
development and fusion of facial processes during embryogenesis, which take place during the tenth week
of pregnancy and involve soft and/or hard tissues of the skull.

Typical forms can be categorised into cleft lip with an incidence of 0.29 per 1000 births; cleft palate (CP),
with an incidence of 0.31 per 1000 births; and cleft lip and palate (CLP) with an incidence of 0.48 per 1000
[1]
[1]
births . Rare, atypical forms show an occurrence of 1 in over 100,000 births . In Italy, about 1 in 800
children are born with a facial cleft.
The aetiology is multifactorial and the causes of facial clefts are unknown but are thought to be caused by
[2]
a combination of both genetic and environmental factors . Lip palate cleft forms because of the maxillary
and medial nasal processes fusion failure, disturbance in mesenchyme cells penetration between facial
[3]
processes or vascular disruption . In addition, the size of the facial processes - closely related to the
ethnicity - can influence the facial morphology, increasing the susceptibility to develop a cleft: in Asian
patients, for example, a smaller and flatter median nasal process, with a smaller third middle of the face and
a more frequent trend to develop a skeletal third class, can result in a higher incidence of cleft (2/100 new-
[4]
borns) in comparison to Caucasians (1/1000 new-borns) and Afro-Americans (0.4/1000 new-borns) .
Previous studies have reported a higher prevalence of dental abnormalities in the permanent dentition
[5]
of cleft children than in the general population . Tooth agenesis, supernumeraries and morphologic
[6]
irregularities of the crown have been significantly associated with cleft size and severity . Embriologically,
the formation of tooth germs and the occurrence of cleft defects have a close relationship in terms of
[7,8]
timing, thus factors leading to cleft could also affect the dental development . In this context, recent
studies have confirmed that genetic mutations (Interferon Regulatory Factor 6, Msh homeobox 1, Paired
Box gene 9 and Transforming Growth Factor-beta) related to oral cleft lead to selective hypodontia and that
Amelogenin X isoform gene, involved in the formation of the dental enamel, could also be involved in the
.
development of clefts, suggesting a genetic association between dental anomalies and clefts [9,10]
The literature regarding dental anomalies in cleft patients is heterogeneous, with dental anomalies rates
varying more than two-fold. This discrepancy may be partially explained by patient selection criteria but
may also suggest a role of external factors in enhancing the risk of tooth anomalies in cleft patients. While
the impact of surgical cleft repair protocols on craniofacial growth has been widely investigated [11-13] ,
few studies have focused [14,15] on their impact on tooth development. Primary cleft lip repair is usually
performed at the age of 3-6 months. Palatal clefts closure is performed using two main techniques
depending on surgical timing. The first technique is a two-stage protocol that consists of two separate
operations: the first serves to close soft palate and is performed in the first/second year of age and the
second serves to close the hard palate and is usually done before the pre-school age. The second technique,
called periosteal plastic of the palate, is a one-stage palate repair, closing the soft and the hard palate at the
same time before 12 months of age. Bone transplantation can be planned from infancy to adulthood to
close the alveolar cleft.

We hypothesise that an early periosteal plastic surgery of the palate could affect dental development by
reducing blood supply to developing tooth germs, thus causing more tooth agenesis and enamel defects
compared to a delayed plastic surgery of the palate, performed later when the tooth germs are already
formed.