Case report: rehabilitation of a child with dentinogenesis imperfecta and congenitally missing lateral incisors.
Dentinogenesis imperfecta (DI) is an autosomal dominant genetic disorder characterised by abnormal dentine structure affecting the primary and permanent dentitions [Barron et al., 2008]. Currently, this anomaly is subdivided into three types [Shields et al., 1973]: DI-I is associated with osteogenesis imperfecta and may be recessive; DI-II and DI-III are restricted to the dentine. DI-II, or hereditary opalescent dentine, is one of the most common dominantly inherited dentine defects. DI-II is characterised by bulbous crowns with marked cervical constriction. DI-III, the rarest, is a form found in a tri-racial population from Maryland and Washington DC (USA) known as the Brandywine isolate. This form is associated with hypotrophy of the dentine. DI occurs in both sexes with an incidence of 1 in 6,000 to 1 in 8,000 [Witkop, 1975; Kim and Simmer, 2007].
Histological studies have shown changes in interglobular dentine and dentinal tubules with pulpal obliteration that could be related to an odontoblast dysfunction [Majorana et al., 2010]. Mutations in the genes encoding the major protein constituents of dentine seem to underlie these hereditary dentine defects [Thotakura et al., 2000; Kida et al., 2009]. The histological appearance of the enamel is reported to be normal although hypocalcified defects may be present. Enamel cracking appears within the enamel itself or along the dentine-enamel junction [Witkop, 1975; Huth et al., 2002].
Clinically this disorder is characterised by opalescent teeth with marked attrition and short roots constricted in the cervical regions. But variations have been reported, especially in relation to tooth colour and attrition pattern [Sapir and Shapira, 2001; Kamboj and Chandra, 2007]. As soon as the primary teeth have erupted, the enamel often becomes chipped and fractures away. The exposed dentine is rapidly subjected to severe attrition and periapical abscess formation is common. In some cases, permanent teeth seem to be less susceptible to an excessive attrition and the dental caries index is low [Sapir and Shapira, 2001; Bouvier et al., 2008]. During a clinical examination, in both dentitions, it is important to consider tooth colour (variable from normal to blue grey or yellow brown), tooth wear, abscess formation, tooth mobility and early loss of teeth [Barron et al., 2008].
Radiographically the crowns are bulbous, with a constricted area at the cement-enamel junction. The roots appear shortened and conical or 'spike like.' In both primary and permanent dentitions the pulp chambers and root canals are often obliterated [Pettiette et al., 1998; Kantaputra, 2001].
Because endodontic treatment is difficult and has a very poor prognosis, early diagnosis is fundamental to enable appropriate preventive interventions and optimal dental treatment thereby minimising nutritional deficits and psychosocial distress [Mendel et al., 1981; Delgado et al., 2008]. A multidisciplinary treatment approach is usually required for treatment of these patients, including orthodontics, prosthodontics, and restorative dentistry [Kindelan et al., 2003]. The treatment strategy includes consideration of a patient's age, function, aesthetics, and severity of the attrition. To maintain the vertical dimension, full coverage crowns are usually recommended [Bouvier et al., 1996; Moundouri-Andritsakis et al., 2002; Groten, 2009]. However, some authors do not recommend using teeth as abutments for fixed partial dentures or removable partial dentures because of their brittleness [Ranta et al., 1993; Henke et al., 1999]. In cases involving excessive attrition, over-dentures or implants with removable prostheses have been proposed [Darendeliler-Kaba and Marechaux, 1992; Henke et al., 1999].
This case report illustrates the chronology and the long-term rehabilitation of a young girl suffering from DI with congenital absence of maxillary lateral incisors.
A 9-year-old girl in good general health presented to the paediatric dentistry department, Hospices Civil, Lyon, (France). She indicated a desire to improve the appearance of her anterior teeth. Her father had been treated for DI type II in the department several few years before. The patient had a permanent dentition. Premolars and canines had recently erupted, and second molars were unerupted.
The oral examination showed an absence of both maxillary permanent lateral incisors that were congenitally missing and replaced by migration of the canines, and a crossbite involving the right canines. Most of teeth appeared discoloured because of pale greyish enamel and brown dentine (Figure 1a). The crowns were intact without loss of enamel or attrition. The girl had good oral hygiene, was caries-free, and did not exhibit any periodontal problems. Radiographically, the crowns were bulbous with marked cervical constriction; dentine and enamel were normal in density, but pulp chambers were obliterated (Figure 1b).
A diagnosis of type DI type II was made from the family history, clinical and radiographic features of this disorder. No history or signs of DI-I, which is associated with osteogenesis imperfecta such as a history of multiple fractures of his long bones, laxity of the joints, blue sclera or hearing loss [Schwartz and Tsipouras, 1984], were present. Dentine dysplasia (DD) may also be differentiated from DI. There were no signs of severe root shortening and tooth mobility as described for DD type I and no pulp stones or 'thistle shaped' pulp chambers were found, which is characteristic of DD type II [Huth et al., 2002].
The main therapeutic goal was to improve the aesthetic appearance of the teeth with a view of reducing the possibility of related psychologic problem. Two possibilities were considered: treating the patient with or without orthodontic therapy. The quickest and most predictable guide for determining the treatment plan was to construct a diagnostic wax-up, which enables a dental team to evaluate the optimal treatment and to determine whether an aesthetic functional result was achieved. Thus, prior to treatment in this case diagnostic casts were obtained and a diagnostic wax-up was created.
In the present case, the permanent maxillary canines were modified to resemble lateral incisors and the diastema between the maxillary central incisors was suppressed. Based on the wax-up, creating a prosthetic space closure by replacing missing lateral incisors using canines seemed to give a beneficial result. Moreover, the facial appearance showed a convex profile, which contra-indicated an orthodontic space opening.
At initial examination and treatment planning time, the patient was deemed to be too young for prosthetic rehabilitation. The treatment planning was defined, therefore, in two phases: an initial stage to ensure the eruption of second molars, a second stage to establish aesthetic appearance by metal ceramic restorations without orthodontic therapy. The patient and her parents were informed of the diagnosis and treatment plan, which they accepted.
[FIGURE 1 OMITTED]
Initial treatment. The patient was examined at regular intervals to check for eruption of the second molars. When the child was 12 years old, all second molars had erupted except the maxillary right second molar. The radiology assessment control showed a mesioangular inclination of the tooth; the bulbous crown with cervical constrictions was the cause of the retention (Fig 1b). Orthodontic traction is a major modality in treatment of a retained molar. However, in this case a large amount of mesiodistal movement and tipping was necessary because the crown was very bulbous with an important constricted area at the cement-enamel junction. It was proposed to reduce a risk of root resorption by making a proximal dental reduction using a bur and waiting for spontaneous eruption. Two months later, the tooth fully erupted and was fitted with preformed metal crown (PMC) (Ion, 3M ESPE). Third molar tooth germs were removed as a preventive measure.
Second stage. When the child was 14 1/2 years old, she was admitted for prosthetic rehabilitation. The bone growth stage had been reached 16 months earlier, and maxillary growth was stable. Initial impressions were taken, and mounted on a semi-adjustable articulator; a second wax-up was made for maxillary anterior teeth. The permanent maxillary canines were modified to re-create normal lateral incisors and maxillary first premolars to resemble canines. The wax-up was duplicated and a vacuum-formed matrix was made. Maxillary and mandibular anterior teeth, premolars and maxillary right second molars were prepared for metal ceramic restorations with metal margins. The preparation depth was 2.0mm for the occlusal surface, and 1.5mm for the labial, lingual and palatal surfaces (Fig. 1c). Pulp vitality was maintained for all the teeth. Maxillary provisional restorations were fabricated chair-side using the matrix and an autopolymerizing acrylic resin (Unifast Trad, GC America). Mandibular teeth were fitted with polycarbonate resin restorations (Ion, 3M ESPE). The anterior guidance was preserved to decrease lateral forces on the posterior dentition. The observation period with the provisional restoration was 4 months.
Occlusal registrations. These were obtained with wax wedges. Complete arch definitive impressions were made with individual impression trays using a one-step technique using poly vinyl siloxane (Express, 3M ESPE). From these impressions, casts were made and mounted on a semi-adjustable articulator to produce 19 individual frameworks for metal ceramic restorations. A precious alloy (Degunorm, Degussa AG) was used for producing all frameworks that were tried in the patient's mouth to check the marginal fit and centric relation position. A low-fusion ceramic (Ducera, Degussa AG) was then applied to produce 16 metal ceramic crowns on incisors, canines, mandibular premolars (Fig 2a). The maxillary right second molar and premolars were fitted with metal ceramic crowns with metal occlusal surfaces (Fig 2b).
[FIGURE 2 OMITTED]
[FIGURE 3 OMITTED]
[FIGURE 4 OMITTED]
Completion of initial treatment. The crowns were tried in the patient's mouth, and minor occlusal corrections were made before the final glazing. A mutually protected occlusal scheme was designed to allow even distribution of forces during lateral movements. There were no interferences in the anterior guidance apart from the contacts on the anterior teeth. All restorations were cemented using glass ionomer cement (Fuji I, GC USA); the patient was satisfied with the treatment result.
The patient was monitored at 3-month intervals for 1 year (Fig. 3), and then once a year. Ten years follow-up revealed a successful result with no functional, aesthetic or radiological problems. A mild gingivitis was present around the restored maxillary anterior teeth (Fig. 4). The patient, now aged 25-years-old is happy with her appearance and molars showed no signs of abrasion.
The choice of the rehabilitation depends on a patient's age at the beginning of the treatment and the severity of the attrition. This case is unusual because the oral situation showed no loss of tooth substance by abrasion or erosion. For this reason the molars of our patient were not treated except the maxillary right second molar. However the treatment was long and complex. Patient collaboration and parent compliance are factors of success.
The importance of maxillary lateral incisors for aesthetics is well documented. Missing maxillary lateral incisors create a major aesthetic problem due to their strategic position in the smile. The two treatment approaches commonly taken are creating adequate space to prosthetically replace the missing lateral incisors or closing the spaces and replacing the missing lateral incisors by the canines [Sabri and Aboujaoude, 2008]. In the case of our patient canine substitution without orthodontic approach was preferred because the adjacent teeth required restorative intervention and the patient's facial profile was relatively convex with normally inclined anterior teeth and a good upper lip support. Moreover, the gingival level of the canines was acceptable because the patient's smile line was low.
Given their reliability and durability, conventional metal ceramic restorations with a complete-crown preparation design generally are a treatment of choice for anterior single tooth restorations and fixed partial dentures (FPDs). However, this technique requires considerable reduction of tooth structure. Modern concepts in restorative dentistry have brought new conservative solutions through bonded porcelain veneers. However, in cases with severe discolouration, full-coverage restorations are required to properly restore teeth. Moreover, complete-coverage crowns are usually the preferred restoration for patients with DI to reduce the risk of enamel fracture [Huth et al., 2002; Kindelan et al., 2003]. Indeed, the risk of enamel fracture is important for the palatal surface of maxillary anterior teeth, particularly if mandibular incisors are in functional contact. Full coverage crowns protect the dental tissues from further destruction [Moundouri-Andritsakis et al., 2002]. Alternative veneering materials, direct or indirect composite, may suffer from degradation of surface features and accretion of surface stain with time [Walls et al., 2002].
Some clinical cases treating patients with DI using all-ceramic restorations have been described in the literature [Moundouri-Andritsakis et al., 2002; Groten, 2009]. Although all-ceramic materials offer certain advantages (aesthetics, biocompatibility), chipping is reported to be a major complication associated with the use of all-ceramic materials, especially zirconia [Kim et al., 2007; Siadat et al., 2007; Groten, 2009; Land and Hopp, 2010]. No all-ceramic restoration has been shown to have a life span equivalent to that of metal ceramic restorations. Further clinical trials are needed. For anterior crowns, a recent review suggests that many all-ceramic restorations were found to demonstrate acceptable longevity compared with conventional restorations (e.g., metal ceramic crowns). But for restoration of posterior teeth, this review suggests that relatively few all-ceramic systems will provide predictable long-term success [Land and Hopp, 2010].
The use of precious metal alloy and low-fusion ceramic provides a lower surface hardness and may decrease the risk of overload on these teeth with limited value [Moundouri-Andritsakis et al., 2002; Bouvier et al., 2008]. Some porcelains with low-fusing temperatures have demonstrated less wear than high-fusing porcelains. Hacker et al.  reported that a low-fusing porcelain abraded enamel less than a more conventional feldspathic porcelain, as have others [Derand and Vereby, 1999]. Moreover, this reduces the risk of chip fractures that can occur on zirconium-based restorations and feldspathic-ceramic crowns.
In this present case, treatment outcomes were favourable. All teeth and all restorations remained free from failures/complications. It illustrates the need for appropriate and timely restorative treatment to prevent deterioration of the dentition. The choice of which restoration to use is indicated by the immediate and long-term needs of each individual patient. Occlusion, aesthetics, and morphology are important but none of these factors is more important than longevity.
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C. Millet *, S. Viennot *, J.P. Duprez **
Depts of * Prosthodontics and ** Paediatric Dentistry, School of Dentistry, University Lyon I, Lyon, France.
Postal address: Prof C. Millet, Faculte d'Odontologie, Rue Guillaume Paradin, 69372 Lyon Cedex 08, France.
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|Author:||Millet, C.; Viennot, S.; Duprez, J.P.|
|Publication:||European Archives of Paediatric Dentistry|
|Article Type:||Case study|
|Date:||Oct 1, 2010|
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