The orthodontic-restorative interface in patients with hypodontia: the patient's journey

Who receives treatment?

There was a wide age range of patients that were treated following joint consultation between orthodontic and restorative clinicians. The majority of patients were adolescents, the mean age at the start of treatment when adult patients were excluded was 13 years and 4 months, however, patients were aged between 11 years 4 months and 51 years 3 months.

The maxillary lateral incisor was the most common tooth to be absent in this group of patients, with the maxillary upper second premolar being the next most common. Table 1 demonstrates the distribution of the missing teeth in this group of patients.

The majority of patients that accepted treatment in the hospital service were missing 1, 2 or more than 6 teeth. Table 2 shows the severity of hypodontia found in these patients: 38% were missing a solitary tooth, whilst patients missing 2 teeth accounted for 24%, with the same number missing six or more teeth. The number of teeth missing ranged from 1–8 teeth with a mean of 3.4 per patient (excluding third molars).

What is the usual patient pathway (Figure 2)?

The patient is diagnosed with hypodontia (usually in general practice) and a referral is sent to an orthodontic, paediatric dentistry or restorative dentistry new patient referral clinic in secondary care.

The patient is examined, records made and the likelihood of combined care assessed. Treatment in either orthodontics or restorative dentistry is commenced or a review appointment is arranged for the patient to be assessed at a more appropriate stage of dental development or dental health. However, most patients with hypodontia could benefit from combined care and therefore a referral is made to an orthodontic-restorative joint planning clinic.

The combined clinic allows the patient to be assessed by both specialties at one appointment. This allows for many treatment options to be fully discussed amongst the clinicians and the patient and his/her family. In addition, the referring specialty has often arranged for special tests to be available, for example, appropriate radiographs, study models, Kessling set-ups, diagnostic wax-ups.

Orthodontic treatment is commenced after appropriate pre-operative models and written consent is secured. As orthodontic treatment approaches completion, the patient is often reviewed by both specialties to assess tooth and root position, spacing, etc. If both parties agree on the appropriateness of the orthodontic outcome, the patient is appointed for removal of the orthodontic appliance(s) and the patient receives his/her appliance to achieve retention.

Referral to restorative dentistry is completed after this, although restorative treatment does not usually begin until 6–9 months after active, orthodontic therapy to allow for maturation of the periodontal architecture. It must be stressed that each patient would have been provided with an orthodontic retainer(s) to wear during this period.

How long does treatment take?

The flowchart detailing the time taken for each phase of treatment is shown in Figure 2. The average, total time from the initial joint planning appointment until the completion of both the orthodontic and restorative treatment was over 3 years (38 months), with a range of 15–61 months for the 19 patients who completed both aspects of treatment in the secondary care setting.

It demonstrates that orthodontic treatment was completed after a mean of 21 months (range 6–44 months), whilst the restorative phase on average took 2 months (range 2–24 weeks). It must be noted that this restorative phase was usually an intermediate phase using minimally invasive techniques (resin-bonded bridges and composite additions) as the patients were generally not of suitable age to commence implant therapy.

Who carries out the treatment?

The majority of orthodontic treatment was completed by specialist registrars under the supervision of their consultant(s), whereas most restorative treatments were completed either by a senior house officer (SHO) or a consultant in restorative dentistry. Approximately 10% of patients received their restorative care in primary dental care.

How many appointments are required?

The number and type of appointments required to complete each phase of treatment are shown in Figure 3. There were substantially more appointments required for orthodontic treatment. A mean of 17 appointments plus one emergency appointment was required for orthodontic treatment. However, it must be noted that the range of orthodontic appointments needed was from 6 to 30. In contrast, the restorative phase usually (around 50% of the cases) only required 3 or 4 appointments (range 2 to 7).

The mean, total number of appointments (orthodontic and restorative) over this period was 23 (range 9 to 34 appointments). This figure has to be regarded with some caution: the number of treatment planning visits was counted as one, however, in many instances there would have been many more, both in the initial single specialty referral, joint treatment planning and subsequent single specialty planning, consent and baseline record stages.

What type of treatment was completed?

The type of orthodontic appliance(s) utilized and the restorations placed are shown in Figures 4a and 4b, respectively. Almost all patients had fixed orthodontic appliance therapy: 11 of the 21 patients required upper and lower fixed appliances, with 8 patients having upper fixed appliance treatment only.

The majority of patients were restored after orthodontic treatment with resin-retained bridges (18 patients). Two patients had both composite additions and resin-bonded bridges, whilst two patients did not complete the restorative phase of treatment.

Discussion

For the purpose of this article, the pathway of patients with hypodontia, requiring a combined orthodontic-restorative dentistry approach, has been presented. It should be noted that the data were taken from clinical notes retrospectively and one has to assume that the dates entered were accurate and therefore the time-scales depicted are truly representative. Some clinical data is described, however, as the number of clinicians involved in care of these patients was relatively large, and no calibration was completed, there could be some inconsistencies.

It was interesting to note that the majority of patients that underwent treatment were missing 1, 2 or more than 6 teeth. Table 1 shows that the most commonly congenitally absent tooth in this group was the maxillary lateral incisor. Both reviews of the literature discussed earlier1^,3 found the mandibular second premolar to be absent most commonly, but the difference between the epidemiological data and that in this audit can be explained by the fact that treatment is more likely to be sought if a lateral incisor is missing due to the aesthetic problems encountered.

The data describes the time-scale and pathway of patients through a combined orthodontic-restorative dentistry approach. However, the patients completed their treatment over eight years ago and many changes have occurred since then: automated reception diaries, changes in personnel and treatment/referral protocols. In addition, government waiting time targets have been introduced for new patient consultations and time from referral to treatment targets are now common place, as discussed below. If the audit were to be repeated for a cohort of patients today, these changes would likely reduce the initial delay before treatment begins. However, both the length of orthodontic treatment and the delay between orthodontic debond and restorative treatment commencing (to allow for healing/remodelling of the periodontal tissues) would be similar today.

Treatment on average took 38 months (involving on average 23 appointments), from the initial joint assessment clinic until the completion of the restorative phase. Patients and their guardians should be aware of the treatment time and that many appointments are required to complete both aspects of treatment. It must be borne in mind that, a study of patient's undergoing orthognathic surgery found that, when accurate information is given to patients, more satisfaction with overall treatment is observed.7

Patients with hypodontia often have complex orthodontic requirements (large edentulous spaces, lack of alveolar processes, non-coincident midlines, orthodontic anchorage problems). It could be surmised that this would lead to extended orthodontic treatment times. Seventy percent of this group completed their orthodontic treatment within 2 years, which would be considered within the accepted range.8

Restorative treatment time was, on the whole, considerably shorter, with the vast majority of patients having either resin-retained bridgework and/or composite resin additions (examples are seen in Figure 5). No patients received dental implant therapy. It was surmised that this was owing to the relatively young age of the patients who were treated, where implant placement would be inappropriate. If these patients were recalled now, it might be expected that several would have had implants placed. If implant therapy is planned, then initial orthodontic treatment can be delayed until the patient is 15 or 16 years old to allow ‘treatment run through’, eliminating the need for intermediate restorations or longer-term wear of removable prosthesis. However, the effect of the malocclusion on the patient's current quality of life has to be considered. Delaying treatment may also interfere with future education and examinations and, in addition, the patient may move away from the area, thus complicating care even further. Having discussed all of these issues, the patient/parent can make an informed decision as to when he/she wishes treatment to commence.

The majority of patients that were treated had 1 or 2 teeth missing (61% of patients in this cohort). A systematic review3 revealed that 83% of patients with hypodontia were missing 1 or 2 teeth. This difference may indicate that some patients missing only 1 or 2 teeth are not seeking treatment, or that they are being treated solely in a primary care setting. Alternatively, the data from the systematic review was taken from the Caucasian populations in North America, Australia and Europe, but differences were found across these continents and therefore the proportion missing 1 or 2 teeth may have been different in our sample population.

Most orthodontic treatment was provided by specialist registrars. This may be a result of the greater number of orthodontic specialist registrars compared to restorative dentistry (currently in Scotland there are 9 orthodontic specialty registrars and 3 post-CCST trainees but only 8 trainees in restorative dentistry). Restorative care was generally provided by either SHOs or by consultants in restorative dentistry. This difference may reflect the complexity of the different treatments. For example, straightforward restorative treatments, like composite additions or resin-retained bridgework, would be completed by more junior members of staff, but more complex treatment would more likely be completed by a consultant member of staff. Alternatively, a shortage of an appropriately trained workforce employed in the departments may have necessitated these differences.

This data compares favourably with a survey of all the orthodontic-restorative cases in an NHS hospital,9 that indicated that the majority of orthodontic treatment was completed by FTTAs, whilst most of the restorative procedures were completed by consultants.

It is important that communication and the referral process between primary and secondary care and between the dental specialties is reliable to ensure that the patients are transferred at the appropriate time. It is therefore essential that a pre-debond examination completed by both the orthodontic and restorative teams is completed. If this is not completed, it could have an adverse effect on the outcome and may possibly lead to orthodontic appliance therapy being re-commenced to create or reduce the amount of space present. If implant therapy is planned, it is important that orthodontic treatment has created a sufficient mesio-distal width to allow implant placement in line with biological principles. A Kessling set-up can be used in the assessment of these dimensions and is often used in planning, regardless of the intended restorative treatment. In addition, the roots of the teeth adjacent to the implant site should, as a minimum, be parallel or, ideally, slightly divergent (Figure 6).

The treatment of this cohort of patients was commenced in 2003/2004, prior to waiting time directives for new patient consultations and any subsequent treatment. The average delay until a new patient consultation was 4 to 5 months; this breaches the current waiting time directive. If the time until a combined clinic appointment (mean of 8–9 months) is considered, this indicates a substantial delay and reflects the complexity of these cases and the demand for joint clinic appointments. The time lag between the assessment visit and the start of treatment is accounted for by the complex treatment planning procedures often required, lack of staff and the length of the existing treatment waiting list. Recent advances in the local service provision has reduced the orthodontic treatment waiting list time considerably and efforts are underway to reduce the wait time for both restorative dentistry appointments and joint clinic appointments. Whilst enhanced communication between the orthodontic and restorative specialties has enabled restorative treatment to commence at the appropriate time (approximately 6 months after orthodontic debond), this is despite the relatively long restorative dentistry waiting list.

Orthodontic retention is discussed with all patients as there is a risk of relapse after treatment. Fox and Chadwick10 found that 61–100% of all orthodontic cases had a ‘deterioration of (their) occlusion’ at least 1 year after all retention measures had ceased. The degree and presence of relapse was dependent on the type of orthodontic appliance used (fixed appliance or URA). If retainers are not worn, then tooth movement can occur and can result in poor aesthetic appearance (Figure 7a). For this reason, immediately following the completion of restorative treatment a vacuum-formed orthodontic retainer (Essix retainer) is made to fit over the completed restorations (Figure 7b).

Following this audit, some local recommendations were made:

In summary, patients and their guardians should be informed that treatment may be complex, requiring excellent compliance, both with respect to oral hygiene measures and attendance. The average time from the first new patient consultation until the end of treatment was approaching four years, with at least 23 appointments; fixed appliance therapy in both arches was usually required and restoration following orthodontic treatment was usually with resin-retained bridgework and/or composite resin additions in the younger patient cohort.