Dentinogenesis imperfecta: full-mouth rehabilitation using implants and sinus grafts – a case report

Treatment in the primary dentition

The aims of treatment are to remove sources of infection or pain, restore aesthetics and protect posterior teeth from wear.6,7 Patients present with this condition affecting their teeth to various degrees so it is not possible to make generalized treatment plans. In general, all patients require a thorough preventive regime, including diet advice and oral hygiene instruction.

Restoration of the dentition ranges from the simple placement of resin-modified glass ionomer cement in areas of enamel loss in the very young and unco-operative child, to placement of stainless steel crowns and direct composite for the more co-operative child.8 Placement of these crowns is advised where there is more extensive tissue loss. Where tissue loss is more severe and little is remaining above the gingivae, extraction of the primary tooth is indicated. If the teeth become non-vital, or abscess formation occurs, primary tooth pulp treatment is contra-indicated and again extraction is necessary.9

Mixed dentition

As the permanent dentition develops it should be monitored closely for tooth surface loss. The amount and distribution of the loss will dictate the type of treatment at this stage. The majority of patients may be treated with cast occlusal onlays on the molar and premolar teeth as this minimizes tooth surface loss whilst maintaining the correct OVD.10 This is also a minimally invasive technique which is of paramount importance at this stage of the patient's dental development.

Aesthetics is normally a concern as the permanent incisors erupt. In the short term, the treatment of choice is direct composite veneers. These are minimally invasive, aesthetic and also help towards better oral hygiene as the irregular chipped enamel surface is now replaced by a polished composite surface.

Permanent dentition

Again, the amount and distribution of tooth surface loss will dictate the level of treatment. At this stage, many patients are considered for full-mouth rehabilitation. However, there are some major differences when treating this group of patients compared to the general population. Classically, these patients have teeth with short, thin roots which have a decreased root surface area available to distribute physiologic forces generated during function.11 However, this is not a contra-indication to crowning the teeth.

Endodontically, the teeth have obliterated pulp chambers and canals. Loss of vitality and subsequent development of apical pathologies are rare,12 however, if orthograde endodontic treatment is indicated it is often technically impossible, generally resulting in tooth loss. Retrograde root treatment is another option but should be contra-indicated for teeth with short roots.13

Case report

The 48-year-old female patient was referred by her GDP complaining of an unstable and unretentive upper partial denture. She gave a history of brown, mottled teeth since childhood that were very brittle and wore easily. She had a long history of dental treatment ranging from simple fillings to complex crown and bridge work (Figure 1). Her main wish was to have fixed replacement of her missing teeth rather than a removable partial denture.

Medically, the patient had controlled hypertension. She was also a non-smoker. She had no apparent family history of the condition affecting her teeth.

Clinically, the patient had a heavily restored dentition. Bridges were present UR3–1 replacing the UR2 and LL3–6 replacing the LL4 and 5. Crowns were present on the UR5,4, UL1,2,3, LL1,2, LR1,2,3,6,7. Retained roots were present UL4,5 and retained LRD,E were present whilst the LR4,5 were developmentally absent.

The patient had a Class II division 1 incisal relationship with a 7 mm overjet and increased overbite. Owing to the loss of tooth structure over the years, the patient was apparently overclosed. In the maxilla an acrylic denture replaced the missing teeth. The denture was tissue-supported. Clinically it was unretentive and unstable, and the patient found it difficult to tolerate. The patient's oral hygiene was good with a BPE score of 0 in all but the lower anterior sextant, which scored 2 due to supra-gingival calculus deposits.

Radiographic examination revealed general root canal obliteration of the remaining teeth and root morphology characteristic of dentinogenesis imperfecta (Figure 2). It also showed caries in the LL6 bridge abutment, a mesial marginal gap in the crown restored LR7, retained roots UL4,5 and retained LRD,E. No periapical pathology was present and bone levels were normal.

The diagnoses reached were as follows:

The initial treatment plan was to restore caries and stabilize her oral health. Treatment options discussed with the patient for restoration of the missing teeth included the fabrication of new upper and lower partial dentures, fixed conventional bridges or implant-supported crowns. The patient was keen to have a fixed solution and opted for implants at an early stage. The initial treatment plan and interpretation was as follows:

After the initial treatment and interpretation were completed it became apparent that the LL6 was unrestorable, so the bridge in the area would need sectioning, leaving the LL3 as a crown. It also became apparent that the UL3 was unrestorable due to insufficient coronal structure and would require removal. The wax-up was discussed with the patient and the definitive treatment plan was completed. It was as follows:

The treatment plan was carried out over the course of a year.

Single vs 2-stage sinus graft procedures

The posterior maxilla is often a difficult area to restore using implants as there may be insufficient bone height between the floor of the maxillary sinus and the oral cavity, rendering traditional placement of implants impossible. Sinus grafting is a procedure which allows the floor of the sinus to be elevated and bone grafted in to the site to facilitate placement of dental implants. This is recognized as a predictable and viable treatment modality.14

Two-stage sinus lifting involves first lifting the sinus floor with either autogenous bone or xenograft bone substitutes (eg Bio-Oss^©), after which three months of healing is allowed, followed by a further procedure to place dental implants. In some cases, it is possible to combine the sinus lift procedure with implant placement in a combined procedure. This is indicated when there is at least 4 mm of bone available under the sinus floor to give initial primary stability for implant placement. It is critical that primary stability of the implants is achieved. If residual bone height is less than 4 mm and/or primary stability of the implant is inadequate, a 2-stage sinus graft procedure is necessary.15 The advantages of the single stage procedure are decreased treatment time and reduced morbidity due to the decreased number of surgical stages undertaken.

The autogenous bone graft has long been considered the gold standard.16 The bone is either harvested from an intra-oral or extra-oral site. Intra-oral sites include the maxillary tuberosity, the ramus and mental region of the mandible. Extra-oral sites include the iliac crest, tibia and calvarium. One disadvantage of these sources of bone is the morbidity from the donor site.

It is now commonplace to use bovine bone alone to graft the sinus or a composite autogenous bone-xenograft bovine bone graft. In this regard, it has been shown that bovine bone alone is a successful material for sinus graft procedures.17,18

The technique used in this case was a single stage procedure. Flap design was a three-sided, full thickness mucogingival flap giving access for a lateral approach (Figure 3). The graft used was locally harvested bone chips and Bio-Oss^© with Bio-Gide^© being placed over the access window in the sinus.19 Good primary stability of the implants was gained and the post-operative radiographs showed good bony infill around the implants placed in the sinus graft (Figure 4).

Overall treatment

The treatment was split into manageable segments. The first major aspect was removal of unrestorable teeth and construction of some partial dentures. This was followed by staged surgical and review appointments in which implants were placed and the bilateral sinus grafts were undertaken (Figure 5).

This was then followed by removal of the old metal ceramic crowns on the remaining teeth, preparation and then temporization. The teeth were temporized with lab-made composite prototype crowns at the new occlusal scheme as they would be in situ a number of months to allow for restoration of the implants and minor adjustments to the occlusal scheme.

The next stage was to expose the implants and placement of the temporary crowns at the new occlusal scheme, again using the diagnostic wax-up as a guide to occlusal dimensions. This was completed over a number of visits, with the occlusion being adjusted as necessary. Once the implants were temporarily restored to the reorganized occlusion, the final metal ceramic crowns of the natural teeth were cemented. These then acted to stabilize the new occlusion while restoration of the implants was completed.

The patient was happy with the result and has adapted to her new occlusal scheme very well. On review, the patient had no major concerns. Her long-term dental care will be carried out by her original GDP and her implants will be reviewed annually. It is worth mentioning that the treatment was completed in April 2009, therefore it is still too early to call the case a long-term success.

Discussion

One of the most important aspects in the treatment of DI is early recognition and diagnosis of the disease and referral to the appropriate specialty. The type of treatment indicated is largely dependent on the age of the patient when first seen,20 but generally involves thorough prevention and protection of the relatively weak tooth structure.

Although no formal study exists comparing the complexity of treatment to the age of initial presentation, it is commonly understood that early management and strict long-term follow-up can lead to a less invasive approach than has been shown in this case. It has been illustrated that a delay in implementing the correct treatment can lead to future treatment being more complex.21

As shown, the complex nature of treatment outlined was not only dictated by the genetic condition, but also by the comparatively late presentation of the patient. At the time of presentation, the patient already had numerous missing dental units and multiple teeth restored with crowns/bridges. This immediately removes the possibility of minimally invasive procedures, and commits the patient to fixed/removable prosthesis. In this case, the patient was not keen to continue down the removable prosthesis pathway and so implant restoration of her missing units was used.22,23

It should be noted that, in this case, the patient suffered from DI Type II, rather than DI Type I that is associated with osteogenesis imperfecta. In Type II, DI is the only trait and bone quantity and quality is the same as an unaffected individual. Although some anecdotal evidence exists regarding implant placement in patients with osteogenesis imperfecta, no long-term controlled studies have been carried out.

This case demonstrates that oral rehabilitation of a patient suffering from Type II dentinogenesis imperfecta using tooth-supported and implant-supported restorations is a viable and clinically effective option.