Common dental anomalies affecting patients with cleft lip and palate

Cleft lip and/or palate (CLP) is the most common congenital abnormality, with a reported incidence of between 1:600 and 1:700 live births.¹ Patients with CLP commonly have impaired facial growth, difficulties with speech, feeding and hearing, psychological problems, dental disease and anomalies.¹

The NHS standard contract for CLP services states that children born with CLP must have early dental intervention.¹ This involves a combination of primary and secondary/tertiary care. By 6 months of age, the cleft team should provide oral health advice. Patients should subsequently have a dental review by 1 year of age by their primary care dentist.² The timeline for cleft lip and primary palate repair is generally between 3 and 6 months, and that for cleft palate at 6–9 months. At this stage, preventive advice should be reinforced, including advice on breastfeeding, bottle-feeding and toothbrushing. Four-to six-monthly dental reviews should then continue with the primary care dentist to reinforce preventive advice and to monitor primary tooth eruption, noting any dental caries or dental anomalies.³ A specialist paediatric dentist should conduct a formal dental review at least at the age of 5 years. Before the age of 10 years, it is essential that the paediatric dentist reviews any child with dental anomalies.¹ These timelines are essential to reduce the burden and impact of compromised dental health on the patient's overall wellbeing.

It has been proposed that dental anomalies form part of an extended cleft phenotype.^4,5 With this in mind, and the importance of identification and management of dental anomalies specified in the NHS standard contract, the aim of this review is to summarize the common dental anomalies associated with CLP. In doing so, primary dental care practitioners will have increased awareness of these anomalies, thereby facilitating improved communication with paediatric cleft dentists to ensure that patients are reviewed in a timely manner in line with recommendations.

The most common dental anomalies affecting patients with CLP are hypodontia, supernumerary teeth, developmental defects of enamel, anomalies in tooth shape and size, including double teeth, ectopic, impacted teeth and transposed teeth, natal or neonatal teeth and root anomalies. These will be discussed in further detail.

Developmental absence of teeth

Hypodontia refers to the developmental absence of any teeth excluding third molars. The overall prevalence in the general population has been reported as 1% in the primary dentition⁶ and 6% in the permanent dentition,⁷ with the lower second premolar being the most commonly missing tooth. The aetiology is thought to be genetically determined, either as isolated gene mutations such as MSX1, or as part of a syndrome, such as ectodermal dysplasia, Down syndrome or Van der Woude syndrome.⁸ Environmental aetiological factors have also been considered, including trauma, irradiation and infections, such as osteomyelitis.

Hypodontia has been widely reported as having a higher prevalence in CLP children.^9,10,11 This may be as a consequence of the structural abnormality.¹² Shapira et al, in their multicentre study, found an overall prevalence of 77% in the permanent dentition of CLP patients. The authors found that the upper lateral incisors on the cleft side were the most frequently missing teeth. On the non-cleft side, the most commonly missing teeth were maxillary second premolars.¹¹ Other studies have reported a lower prevalence of 53% and 46%.^9,13 Suzuki et al reported a prevalence of 16% in the primary dentition.¹³ The evidence suggests that the overall reported prevalence of hypodontia in patients with CLP is significantly higher than unaffected individuals in both the primary and permanent dentition. The primary and permanent upper lateral incisors are the most commonly missing teeth (Figures 1 and 2); however, other teeth, including premolars, may be missing (Figure 3). Hypodontia is more likely to occur in the cleft region. Dentists must be vigilant to identify teeth that have not erupted as expected within ‘normal’ dental development timelines because these may be congenitally missing. If missing teeth are suspected, appropriate radiographic examination should be undertaken. If delayed loss of a primary molar has occurred in one or two quadrants, an intra-oral peri-apical radiograph should be taken. If delayed loss is present in three or four quadrants, a dental panoramic tomograph (DPT) is indicated. If infra-occluded primary teeth are evident in a patient over 10 years of age, a peri-apical radiograph or DPT should be taken if infra-occlusion is evident in one quadrant, or two or more quadrants, respectively.¹⁴

Advice should be sought from paediatric, orthodontic and restorative colleagues for medium- and long-term treatment planning. In cases where premolars are missing, the aim should be to retain primary molars until a definitive orthodontic plan is made. Healthy retained primary molars should be protected with the use of fissure sealants.¹⁵ If primary molars are carious, but restorable, restoration should be considered in the form of stainless steel crowns for occlusal or proximal caries,¹⁶ or composite restoration for occlusal caries.¹⁷ If unrestorable caries or severe infra-occlusion is evident, extraction will be required and multidisciplinary input should be sought for replacement options and the requirement of space maintenance.

Supernumerary teeth

Supernumerary teeth refer to teeth or teeth-like structures, which occur in addition to the normal complement of 20 teeth in the primary dentition, or 32 teeth in the permanent dentition. They can be classified according to their location (mesiodens, paramolar, distomolar) or morphology (conical, odontome, supplemental, tuberculate). The overall prevalence in individuals without CLP is thought to be 1% in the primary dentition and 2% in the permanent dentition.¹⁸ Supernumerary teeth have been reported as the second most common dental anomaly affecting the cleft area^19,20 in both the primary (Figure 4) and permanent (Figure 5) dentition, with a reported prevalence of 22% in the permanent dentition.²¹ Supernumerary teeth can result in failure of eruption of adjacent teeth, particularly upper central incisors. The incidence of this will be increased for the odontome and tuberculate types.²² Crowding, rotations and displacement of adjacent teeth may also occur, as well as root resorption, dilaceration or arrested root development of adjacent teeth. Removal of supernumerary teeth would be readily considered when failure of eruption or damage to adjacent teeth has occurred.²³

Developmental defects of enamel

Developmental enamel defects (DDE) are frequently observed in patients with CLP.²⁴ The aetiology of these defects in patients with CLP is unclear, but it has been hypothesized that they may occur secondary to metabolic or nutritional deficiencies, or surgical interventions during palate repair, resulting in altered blood supply to developing tooth germs.²⁵

Hypoplastic enamel (Figure 4) and hypomineralized enamel (Figure 6) are the most frequent enamel defects seen in patients with CLP. Hypoplastic enamel represents a quantitative defect due to deficient enamel matrix secondary to disturbance during the secretory stage of amelogenesis. Hypoplastic enamel will typically appear hard and translucent with a reduced thickness, and may exhibit pitting or grooves. Hypomineralized enamel represents a qualitative enamel defect occurring due to disturbances in enamel matrix mineralization. Teeth will demonstrate white, yellow or brown opacities, and will be prone to wear and post-eruptive breakdown. Patients with enamel defects may experience sensitivity, pain and aesthetic concerns. Furthermore, it has been well reported that it can be difficult to achieve local anaesthesia in hypomineralized teeth.²⁶ In light of this, consideration should be given to the use of inhalation sedation, anaesthetic adjuncts, such as intraligamental infiltrations and pre-operative treatment with fluoride varnish.^27,28,29

Early identification and protection of teeth with DDE is essential. Prevention should be provided to patients in the form of oral hygiene instruction, diet advice and fluoride varnish application as per the Delivering Better Oral Health Toolkit.³ Children should be treated as at high risk of dental caries, and fissure sealants should be placed on teeth with enamel defects. Agents such as casein phosphopeptide amorphous calcium phosphate can be used to encourage remineralization and desensitization. In posterior teeth with post-eruptive breakdown or dental caries, restorations or extractions may need to be considered.³⁰

Anomalies in shape and size

Developmentally missing teeth are often associated with an overall reduction in tooth size.³¹ Patients with CLP may have teeth with anomalous size or shape, commonly permanent lateral incisors.¹⁹ Microdont teeth, teeth smaller than normal for the individual tooth type (Figure 7), macrodont teeth, teeth larger than normal for the particular tooth type (Figure 2), or teeth with abnormal crown morphology (Figure 5) can cause aesthetic concerns due to spacing and irregular crown shape. This can have psychological effects on self-esteem and confidence. Furthermore, diminutive permanent lateral incisors can be associated with centreline shifts, reduced overjets and impacted maxillary canines, which can increase orthodontic and surgical burdens.³²

Double teeth have also been frequently found in patients with CLP (Figure 8). They are thought to occur more commonly in the primary dentition and in the mandibular arch.¹³ Double teeth can be more prone to dental caries or periodontal disease due to poor plaque control and subgingival fissure extent. Anterior crowding and compromised aesthetics may also occur. If in the primary dentition, a double tooth may be indicative of subsequent hypodontia of the permanent tooth, mainly affecting upper lateral incisors. However, the permanent tooth may still be present as normal (Figure 9).³³

Ectopic and impacted teeth

Ectopic teeth are those that have erupted into an atypical position. In the general population, the most common teeth to erupt in an atypical position are first permanent molars and permanent canines, with a prevalence of 4% and 1.5%, respectively.^34,35 Although there is limited literature on the reported prevalence in patients with CLP, it may be up to 31–45% (Figures 3 and 10).³⁶

Ectopic or impacted teeth can result in root resorption of adjacent teeth, crowding or displacement of adjacent teeth and pathology, such as cystic formation.^35,37 Furthermore, management of these teeth can be complex with patients often requiring surgical and orthodontic intervention for exposure and bonding of impacted teeth. It is important that dental development in patients with CLP is monitored. Asymmetrical eruption of teeth should be investigated and upper canine teeth should be palpated from the age of 8 years.³⁷

Ectopic teeth have also been associated with other anomalies, including hypodontia and microdontia,³⁸ and a holistic approach to examination and diagnosis must be considered, alongside referral to secondary care.

Transposition

Transposition of teeth refers to the interchange in position of two adjacent permanent teeth. It is classified as either complete, whereby the entire crown and root of the teeth have exchanged places or incomplete when the roots remain in their normal position but the crown is transposed.³⁹ The upper permanent canine is the most frequently transposed tooth and reported prevalence is low at 0.6%.⁴⁰ Prevalence in CLP patients has been reported as 14% (Figure 11).⁴¹

Management of transposed teeth can be challenging, and early identification of abnormal eruption paths is beneficial to enable early orthodontic intervention to correct tooth position.³⁹ If transposed teeth have erupted, composite masking in combination with bleaching in those over the age of 18 years can be considered to improve the aesthetic appearance.

Natal and neonatal teeth

Natal teeth are teeth that are present in the oral cavity at birth, while neonatal teeth are those that erupt in the first 30 days of life. These teeth may be part of the normal complement of 20 deciduous teeth. They are usually conical in shape with a yellow/brown colour. The prevalence in the general population is varied, but is considered to be between 1:800 and 1:30,000.⁴² A higher prevalence of natal (Figure 12) and neonatal teeth has been found in patients with CLP. A study reported the incidence to be 2% in patients with unilateral CLP and up to 10% in patients with bilateral CLP.⁴³

Identification of these teeth and referral to secondary care is essential to prevent associated complications, including difficulties with feeding, traumatic injury to the ventral tongue and mobility, with subsequent aspiration risk. If an aspiration risk is suspected, removal should be considered, either by GDPs or specialists. If teeth are mobile with no aspiration risk, appropriate follow up should be arranged to ensure there is no increase in mobility.

Root and pulp morphological anomalies

Taurodontism, and dens invaginatus and dens evaginatus have been associated with CLP patients. Taurodontism refers to teeth with enlarged pulp chambers, root shortening and apical positioning of the pulpal floor with lack of a cervical constriction at the cemento-enamel junction (Figure 13). Teeth can be classified as hypotaurodont (slightly enlarged pulp chamber), mesotaurodont (moderately enlarged pulp chamber) and hypertaurodont (very enlarged pulp chamber).⁴⁴ The reported prevalence in a general population is considered to be 0.25–11.3%.^45,46 Permanent molar teeth are most affected.⁴⁷

Patients with CLP have been found to be significantly more likely to have taurodontism.⁴⁸ Taurodontism can increase the difficulty of endodontic treatment due to abnormal pulp morphology and thin pulp floors. Furthermore, orthodontic treatment may be challenging due to reduced anchorage value and increased tendency of root resorption.

Dens invaginatus (Figure 14) and dens evaginatus refer to developmental malformations of tooth resulting in an invagination or tubercle formation, respectively. Upper permanent lateral incisors are most frequently affected.⁴⁹ Despite being rarely found, these anomalies have been reported to be more prevalent in CLP cohorts.⁵⁰ It is essential that these teeth are identified early. If palatal pits are present in dens invaginatus cases, they should be sealed to reduce the risk of loss of vitality. If loss of vitality does occur, endodontic treatment can be challenging. In dens evaginatus case, tubercles should be sealed. If occlusal interferences are present, the opposing occluding surface can be minimally reduced and fluoride varnish applied.

Discussion

Analyses of the above dental anomalies in patients with CLP suggest that the prevalence of dental anomalies is higher in this cohort compared to unaffected individuals. This is demonstrated in published literature. Tannure et al conducted a systematic review and meta-analysis of six studies and concluded that there was a higher number of dental anomalies in the permanent dentition in patients with CLP than unaffected individuals. This included hypodontia, microdontia, supernumerary teeth, tooth malposition, abnormalities in tooth morphology and tooth impaction.²⁴ Furthermore, a retrospective study analysing the records of 162 patients with CLP found that 94% of patients had at least one dental anomaly, and 34% had two or more anomalies.⁵¹ A recent service evaluation of 62 18-month-old babies with CLP found that 57% of patients presented with a dental anomaly – hypodontia, hypomineralization or hypoplasia, and emphasized the importance of early dental review and intervention in this group of patients.⁵²

Alongside this predilection for certain anomalies, there also appears to be a relationship between cleft formation and tooth formation with dental anomalies more commonly appearing in the cleft site.²⁴ This has been evidenced through the identification of common genetic factors contributing to dental anomalies and clefts.^4,53 Hypodontia appears to be the most commonly found dental anomaly, followed by supernumerary teeth.⁵⁴ The teeth most commonly affected are the maxillary lateral incisors and premolars.⁵ The severity of the anomaly may be correlated with the severity of the cleft, and patients may present with multiple anomalies.⁵⁵

Based on the robust evidence that CLP patients are at higher risk of dental anomalies, NHS England, in their published service specification for patients with CLP, has highlighted the importance of patients with dental anomalies having a dental review by a specialist paediatric dentist before the age of 5 years.¹ Through revision of the common anomalies, and associated problems, it is clear to see why this is the case. Patients with dental anomalies require early identification and intervention to prevent deterioration and avoid potentially severe problems. A multidisciplinary approach is important, with GDPs, paediatric dentists, orthodontists and restorative dentists to enable holistic treatment planning, promote patient wellbeing, minimize dentally related negative psychosocial effects and reduce the long-term burden of dental care that this cohort of patients will require. GDPs have an essential role in the provision of preventive advice in line with Delivering Better Oral Health guidelines. Enhanced measures should be followed as per this toolkit for CLP patients with anomalies predisposing them to dental caries.³

Conclusion

Patients with CLP will require significant medical intervention throughout their lifetime. Awareness of the increased prevalence of certain dental anomalies and facilitating early intervention is paramount in reducing the dental burden on these patients. A shared-care approach is required by primary and secondary/tertiary dental services to enable optimal care and support to be provided to this cohort of patients.