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Macrodontia is an uncommon dental anomaly that can present in both primary and permanent dentition. It has often been reported to occur concomitantly with other dental anomalies and has also been an established clinical characteristic of numerous systemic conditions and syndromes.
The following case reports illustrate the challenges of managing macrodont teeth in view of the various treatment options available, as well as the multiple factors that tend to influence each case individually.
Clinical Relevance: This article highlights the importance of early referral and a multidisciplinary approach to treating patients with dental anomalies.
Article
Macrodontia is the term given to teeth which are larger in size than the normal respective tooth type and have equally enlarged pulp morphology, crown and root. This dental anomaly may also be referred to as megalodontia or megadontia, and may be associated with numerous syndromes and medical conditions (Table 1). It can be present in both primary and secondary dentition.
Pituitary gigantism
Enlargement of all organs, soft tissues and skeleton, macrodontia due to pituitary overproduction3,4,6,7
KBG syndrome (KBG stands for first 3 patients reported with syndrome)
The following distinctions have been made between the various types of macrodontia:
True macrodontia: This is quite rare and occurs when most of the dentition is affected, as in cases of hemi-hyperplasia or oto-dental syndrome.7
Relative generalized macrodontia: This refers to the entire dentition and may occur as a result of hormonal imbalance, for example in pituitary gigantism.3,7
Isolated/false macrodontia: This usually affects single teeth.
It must be remembered that small jaws in relation to the teeth might give the impression of generalized macrodontia. This concept still seems to create some controversy where early human remains are studied. Early dental dimensions classify as megadont teeth, but this might not be the case when one takes into consideration the small bodies of early human species.9
Epidemiology
Isolated macrodontia have been reported to have a prevalence of 1.1% in the permanent dentition of British children in contrast to 2.5% in the Chinese population. The prevalence of macrodontia in the deciduous dentition is unknown. Males (1.2%) seem to have a higher predisposition than females (0.9%).10,11,12
Macrodontia have been found more frequently in incisors, mandibular premolars and third molars.7,12 This tendency has been reported to occur bilaterally.
Aetiology
Tooth formation and differentiation is a complex process and is vulnerable to the influence of various environmental and genetic factors. Size and shape of permanent teeth can be affected by altered endocrine functions, as well as trauma and infection in deciduous predecessors.8
The literature has never been very clear in defining the cause or origin of macrodont teeth, however, the following are the two main theories that are most commonly described.
Various authors have emphasized the importance of classifying macrodontia as separate dental anomalies from fusion or gemination.4,11 Fusion occurs when two adjacent teeth join, from the dentine and/or enamel, to form one large tooth. Gemination takes place when a tooth germ fails to undergo complete division. The resultant number of teeth within the arch is usually the best indicator to distinguish one anomaly from the other, especially when both may produce the same range of clinical presentations. Incisal notching in large teeth has also been suggested as a clinical sign which will aid differentiation between double teeth and macrodontia.11
Another school of thought is that macrodontia can actually occur as a result of fusion or gemination, and hence explain the production of a large-sized tooth.3,13 It is more generally accepted that macrodontia describes the appearance of anomalies, whilst fusion/gemination are terms which explain the embryological cause of such anomalies.14
Clinical appearance
Macrodont teeth are usually significantly larger than the normal corresponding tooth size. Where a normal central incisor measures an average of 8.6mm, macrodont central incisors have been reported to measure between 12 mm to 14.5 mm, mesiodistally.15 In the case of premolars, the average-sized tooth is 7.3 mm in mesiodistal and 8.2 mm in buccolingual dimension, whilst reported macrodont premolars have measured up to 15.2 mm mesiodistally and 13.1 mm buccolingually.12
Macrodont premolars tend to have an ovoid molariform crown with numerous cusps and irregular fissures. Incisors, on the other hand, are usually shovel-shaped with abnormally wider crowns than their counterparts. It is not uncommon for a patient to have other dental anomalies when macrodonts are present.
Management
The major complaints associated with macrodontia include:
Eruption problems;
Caries;
Crowding;
Poor aesthetics;
Malocclusion;
Alteration in gingival contour;
Periodontal health.
The following case reports illustrate different treatment modalities for macrodontia.
Case 1
A 9-year-old boy was originally referred to an orthodontic practice by the general dental practitioner for the management of an unusually large ‘odontome-like’ incisor. Subsequently, he was referred to the orthodontic department at Chesterfield Royal Hospital for further management.
Medical history revealed Type I diabetes, with no relevant family history of any dental anomalies. Dental examination revealed an early mixed dentition, with a Class II division 2 malocclusion complicated by UL1 fused to a supplemental incisor. This tooth had a mesiodistal width of 14 mm (Figure 1 a–c). All other permanent teeth were present and of normal morphology. The upper labial segment was potentially crowded and the lower arch was moderately crowded. The patient had an overjet of 3 mm and complete overbite.
Figure 1.
(a–u) Case 1.
Radiographs showed that the macrodont UL1 had two roots, however, the pulp morphology was deemed unfavourable for endodontic treatment with subsequent root sectioning (Figure 1d). Possible treatment options were discussed in a joint orthodontic/restorative dental consultation clinic. The UL1 was extracted in an atraumatic way under general anaesthetic in view of the patient's medical history (Figure 1e, f). The initial plan was to allow UL2 to erupt in order to assess aesthetics fully and to analyse space requirements. On the following review appointment, it was discovered that the patient had a supernumary upper central incisor, which had not been noted on the original orthopantomogram (OPT) and this was labial to the UR2 (Figure 1g).
The patient was fortunate that both these central incisors were of similar sizes and in a manageable position. It was decided to use fixed appliances to move UR1 to UL1 position and to move the supplemental incisor into the space originally occupied by the UR1 (Figure 1h-l). This successfully resulted in four reasonable-sized incisors in acceptable positions. Aesthetic results were more than adequate once minor restorative adjustments to the clinical crowns had been carried out. Towards the end of treatment, the patient requested a frenectomy to reduce the prominent and malpositioned upper labial frenum (position indicated on Figure 1g and subsequently on Figure 1k). This malposition occurred as a direct result of the unusual movements of the incisors required during the comprehensive fixed appliance treatment (Figure 1 m-o). This case has been finished to an acceptable standard as illustrated in the final photographs (Figure 1 p-u).
Case 2
A fit and well 11-year-old boy was referred to Chesterfield Royal Hospital for an orthodontic opinion. His main complaint was the unaesthetic appearance of one of the upper front teeth.
The patient presented with a Class II division 2 incisor relationship and an overjet of 3 mm on a mild skeletal II base. He was still in the mixed dentition stage and had mild crowding in the upper arch. Intra-orally, the UR2 was found to be macrodont and radiographic examination showed that this excessive tooth width extended all the way up to the root (Figure 2a). This meant that a full coverage crown restoration would have never matched the UL2 satisfactorily at the gingival margin. The OPT revealed that the rest of the dentition was chronologically still only about nine years of age.
Figure 2.
(a–d) Case 2.
After examination on a joint orthodontic/restorative dental consultation clinic, all possible treatment options were discussed with the patient and his parents. This included extraction of the macrodont UR2 with replacement by the UR3, which meant that the patient could have a complete dental arch without the need of any permanent prostheses. Another option was to allow the UR3 to erupt into its ideal position, and prepare the geminated UR2 space for a single tooth implant or an adhesive bridge. Though this would result in an ideal appearance, it would definitely entail an extended treatment time. Finally, it was decided to review the case in a year which would also give plenty of time for the patient and his parents to decide which treatment option would be ideal for them.
When the patient was subsequently seen at the next review appointment the canines were not yet fully erupted, so it proved difficult to predict their final position. Judicious incisal edge trimming, as well as mesial and distal discing of the geminated UR2 was carried out at this appointment to reduce the horizontal width of the tooth in order to gain a little more space for the canines to erupt and to improve aesthetics (Figure 2b).
The patient was reviewed once again after 8 months, when the canines were found to have erupted nicely into the correct position and the appearance of the reduced UR2 appeared quite acceptable. It was explained that the option of further alignment of the teeth with fixed appliances was still possible, but both the patient and parents were happy with the result and did not wish for further orthodontic treatment (Figure 2c, d).
Case 3
Patient 3 was referred for an orthodontic assessment by the GDP. She disliked the general appearance of her teeth and was keen for orthodontic treatment. This 11-year-old girl was medically fit and well, with no history of trauma or habitual dental behaviour.
On examination, the patient had a Class I occlusion on a skeletal I base with competent lips and moderate crowding. The overjet was 3 mm and the overbite was increased and complete. Both upper and lower centrelines coincided with each other and her facial midline. There was a midline diastema with a low fraenum attachment, which blanched on tension. Dentally, the UL6 was hypoplastic and satisfactorily restored. Both lower second premolars had unusual morphology, being wider mesiodistally than an average sized premolar (Figure 3a).
Figure 3.
(a–j) Case 3.
Radiographic examination excluded any other cause for the diastema other than the fraenum and showed the presence of all other permanent teeth, including the developing molars (Figure 3b).
The treatment plan included extraction of both upper first permanent molars, having taken into consideration the poor prognosis of the hypoplastic UL6. After six months, an upper Nance palatal arch was fitted to the then fully erupted second molars, together with upper and lower fixed appliances. A fraenectomy was also carried out under local anaesthetic, in order to facilitate the closure of the diastema.
In the lower arch it was decided that enamel stripping alone would not allow sufficient tooth tissue reduction, as the premolars were too wide mesiodistally. For this reason, both lower macrodont second premolars were extracted and the spaces were satisfactorily closed during comprehensive fixed appliance treatment (Figure 3 c–j). This case took no more than 20 months to complete.
Discussion
One can appreciate the importance of a multidisciplinary approach in the management of macrodont permanent teeth, as shown in the cases illustrated above. This is not only essential for the patient to get the best possible treatment outcome, but also to allow anticipation of and prevention of any future complications.
The major treatment dilemmas are whether to:
Retain;
Retain with restorative adjustments;
Enamel reduction/stripping;
Endodontic treatment followed by surgical hemisection;
Extraction and closure of space;
Extraction and prosthetic replacement.
The decision will depend on various other important factors.
Associated dental anomalies
The presence of a supplemental supernumerary tooth in Case 1 led to a more elegant solution than originally expected following the removal of the massive upper central incisor. This extra tooth allowed for reproduction of the ‘normal’ number of incisors in the premaxillary area. One has to analyse the entire dentition thoroughly for other associated dental anomalies, as well as rule out other associated systemic conditions, such as the ones shown in Table 1, which may also require consideration.
Age of patient and motivation
Motivation and compliance are two important factors that tend to vary with younger patients and this has to be taken into consideration before embarking upon a lengthy treatment plan. The patient must be able to achieve high levels of oral hygiene before the start of treatment in order to get long-lasting successful outcomes, if comprehensive fixed appliance treatment is to be used.
Aesthetics
Aesthetics is a treatment aspiration on which few patients are willing to compromise. Management, however, has to be tailored to the patient's needs and it is important to keep the patient's main complaint in focus. The resultant appearance might be acceptable for one particular patient but not for another. In case 2, the patient was happy with the appearance of the macrodont incisor once enamel reduction had allowed full eruption of adjacent teeth, even though the orthodontist was keen to carry out fixed appliance treatment.
Other important aesthetic considerations before treatment include the patient's smile line, facial asymmetry and the amount of incisor on show at rest and on smiling.15
Pulpal morphology
Radiographic investigations at the start of treatment can often determine which treatment options are viable and which are not in a particular case scenario. It is particularly important to identify when pulp and root morphology are unsuitable for predictably successful endodontic treatment and subsequent sectioning to take place.
Spacing, crowding and underlying malocclusion
Space analysis is most important where orthodontic treatment is being considered because all aspects of the malocclusion have to be addressed. Treatment planning may become quite complex, as in Case 3, where a diastema is present, as well as crowding elsewhere in the arch.
If the macrodont tooth is situated in an unobtrusive position in the jaw, it is sometimes appropriate to accept this tooth in the arch and just address other complaints the patient might have. This is rarely the case, however, because the abnormal size usually requires significant restorative adjustment to satisfy functional and aesthetic requirements. Intervention might range from enamel stripping to radical anatomical reshaping, using composite resin or even crown or veneer provision. It has been reported that an average of 0.4mm of enamel can be safely stripped from a tooth without any major complications.16 This is also a commonly applied technique in orthodontics to gain space for tooth alignment.
Crown division and/or surgical hemisection might be the ideal treatment option if a macrodont tooth has resulted from fusion or gemination. Radiographic examination of the pulp and root morphology is mandatory in order to reveal whether these procedures are appropriate. During tooth sectioning, pulp exposure is inevitable, the complexity of the treatment depending on the details of pulpal anatomy. This will therefore necessitate subsequent endodontic treatment.
Bone loss should always be limited to the minimum necessary to complete the surgical procedure and, when macrodont teeth are removed, the surgeons must always be reminded of the damage they may cause if a careful technique is not used. Excessive bone loss has severe implications on aesthetics and future treatment options.
Conclusion
Managing macrodont dental anomalies can prove to be very challenging. Early referral to a multidisciplinary clinic is in the patient's best interest. It should always be kept in mind that achieving optimum aesthetics is just as important as an acceptable functional occlusion in order to achieve the best clinical outcome and a happy patient.
