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Treatment of severe hypodontia–oligodontia—an interdisciplinary concept
Int. J. Oral Maxillofac. Surg. 2007; 36: 473–480 doi:10.1016/j.ijom.2007.01.021, available online at http://www.sciencedirect.com
Invited Review Paper Oro-Facial Rehabilitation
Treatment of severe hypodontia–oligodontia—an interdisciplinary concept
N. Worsaae1, B. N. Jensen2, B. Holm3, J. Holsko4 1 Department of Oral and Maxillofacial Surgery, Glostrup University Hospital, Glostrup, Denmark; 2Department of Oral and Maxillofacial Surgery, Aalborg University Hospital, Aalborg, Denmark; 3Department of Oro-Facial Rehabilitation, School of Dentistry, University of Copenhagen, Copenhagen, Denmark; 4Private Orthodontic Practice, Aalborg, Denmark
N. Worsaae, B. N. Jensen, B. Holm, J. Holsko: Treatment of severe hypodontia– oligodontia—an interdisciplinary concept. Int. J. Oral Maxillofac. Surg. 2007; 36: 473–480. # 2007 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The authors’ experience with oral rehabilitation of patients suffering from oligodontia (i.e. six or more congenitally missing permanent teeth, third molars excluded) is reported. The concept is based on an interdisciplinary team approach involving pedodontists, orthodontists, maxillofacial surgeons and prosthodontists. A series of 112 consecutive patients suffering from oligodontia were referred from 1997 to 2001. Ten of the patients (8.9%) suffered from ectodermal dysplasia. The total number of missing teeth was 1126, with an average of 10 per patient. Ninetytwo patients had either finished treatment or were on an active treatment schedule. Of these, 97% underwent some kind of orthodontic treatment. Of the 112 patients, 51 had finished treatment at the end of the follow-up period (mean 28 months, range 1–68). Of these, fixed implant-supported prosthetic restoration was used in 90% to replace missing teeth, often combined with alveolar ridge augmentations (73%), sinus floor augmentation (43%), inferior alveolar nerve transposition (18%) and orthognathic surgery (27%). Early diagnosis, and comprehensive treatment planning with good coordination and timing of the individual treatment phases are decisive for a successful treatment outcome. The therapeutic concept is presented with special emphasis on surgical aspects.
Hypodontia of permanent teeth, third molars excluded, has a prevalence of about 8%, with an almost equal sex distribution in the Danish population11,15. The prevalence declines with increasing number of missing teeth. RØLLING15 reported only 0.16% of 3325 Danish children with five or more missing permanent teeth. In a recently published study a rate of 0.16% with six or more missing teeth was reported16. In the study by RAVN & NIELSEN11 of 1530 Danish school children, 0.26% had six or more missing teeth. 0901-5027/060473 + 08 $30.00/0
In a Swedish study4 the prevalence of hypodontia was 7.4% with 0.19% missing six or more permanent teeth. SCHALK-VAN DER WEIDE18 defines, in her Dutch study, hypodontia of six or more permanent teeth as oligodontia and estimates the prevalence to be 0.08%. Oligodontia is therefore a relatively rare condition, probably affecting about 0.1–0.2% of the population. Simultaneous with oligodontia are often different positional changes of the existing teeth, their morphology and size14,18,20. Characteristic changes are also growth
Key words: hypodontia; oligodontia; treatment; interdisciplinary. Accepted for publication 25 January 2007 Available online 12 April 2007
disturbances of the maxillofacial skeleton and thus the facial appearance2,10,17. Oligodontia may be associated with other ectodermal abnormalities and syndromes2,3,8,18,19,20. The treatment of patients with oligodontia is therefore often complex. The purpose of this article is to report the authors’ experience with an interdisciplinary, centralized treatment approach to this relatively small group of patients involving pedodontists, orthodontists, prosthodontists and maxillofacial sur-
# 2007 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
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geons. The present study will focus upon treatment planning and the various surgical treatment options in an interdisciplinary context. The more detailed treatment outcome in the longer term will be reported in a subsequent publication.
Demography
The population of Northern Jutland is approximately 500,000 with an actual birth rate of 6000 per year. Previous experience with treatment of patients with multiple missing teeth had emphasized the need for an interdisciplinary collaborative effort. A centre for management of patients with oligodontia was therefore established in 1997 at the Department of Oral and Maxillofacial Surgery, Aalborg University Hospital. Patients with six or
more missing teeth could be referred to the Centre of Hypodontia independent of age. The interdisciplinary concept: conferences and treatment planning
After a primary examination of the patients, the patients are presented at a conference with participation of pedodontist, orthodontist, prosthodontist, and oral and maxillofacial surgeon. Associated specialties are anaesthesiology, paediatrics, genetics, and nuclear and internal medicine. The purpose of the conference is: (1) to establish a treatment plan in agreement with the wishes of the patient (and parents); (2) to evaluate and adjust an on-going treatment schedule according to a previous treatment plan, and follow up on
intermediate treatments in young patients during growth; (3) to evaluate the final outcome of treatment in order to build up team experience for improvement of treatments in the future; (4) to inform patients and parents about consequences of missing teeth, treatment options, and to offer genetic counselling. The clinical and radiographic examinations (Fig. 1), including cephalometric radiographic analysis, orthopantomographic and intraoral radiographs, combined with study casts and diagnostic wax-ups on the casts (Fig. 2), constitute the basic material when treatment planning is performed at the conference. When young patients during growth are presented, an overall treatment schedule
Fig. 1. Treatment planning. Preoperative profile clinically (A and B) and radiographically (D and E) of a 17.5-year-old patient with 13 missing permanent teeth, deep bite, reduced lower facial height, lip eversion and bimaxillary retrognathia. (B and E) Preoperatively but with a simulated, ‘diagnostic’ bite raising and advancement of the paranasal soft tissue by soft retrievable material placed in the anterior upper vestibular sulcus. (C and F) Three years later, after bimaxillary orthognathic surgery, including a down-sliding Le Fort I osteotomy, bilateral sinus lift, but before implant insertion and final prosthetic treatment.
Treatment of oligodontia
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Fig. 2. Study casts before (A) and after (B) wax-up on the casts of a patient with oligodontia missing 12 permanent teeth. The lines indicate the planned orthodontic uprighting of the teeth. Note, the impacted primary molar, the reduced vertical growth of the alveolar process, and the disturbed eruption and tilting of the adjacent teeth.
and planning of the intermediate treatment is outlined. Intermediate treatment is then coordinated with and generally performed in the public health care system. When the orthodontic treatment is finished and the patients have reached an age of 17–18 years, they are rescheduled at a subsequent conference. The patients are then usually ready for planning of the final treatment, i.e. orthognathic surgery, bone augmentations, dental implants and prosthetics. Orthodontic treatment takes place either in the public health care system or in private practice. The surgical treatment, including orthognathic, is performed at the Department of Oral and Maxillofacial Surgery, Aalborg University Hospital. The prosthetic treatment is performed by prosthodontists in private practice. The treatment is financed by public means. Patients
There were 112 patients (54 females, 58 males) with an average age of 20.5 years (range 8–48 years) consecutively referred from July 1997 to March 2001. Children in the public health care system were referred after a diagnosis of oligodontia was established during orthodontic screening procedures, which normally take place at the age of 10–11 years for girls and 11–12 years for boys. Adult persons were referred by private practitioners according to their need for treatment. Many of the adult patients had never had a genuine treatment offer during childhood. The distribution of the 112 patients according to age at the time of referral is shown in Fig. 3. Eighty-one (72%) of the patients were 15 years old or more when referred, and 31 (28%) of the patients were 25 years old or more. The total number of missing teeth of the 112 patients was 1126 (mean: 10 per patient, range 6–25). The distribution of
Fig. 3. Distribution of 112 patients with oligodontia according to age at time of referral.
the 112 patients according to gender and number of missing teeth per patient is presented in Fig. 4. Forty-one patients (37%) were missing 10 or more permanent teeth. The location of the 1126 missing teeth is shown in Fig. 5. The second upper and lower premolars followed by first upper premolars, lateral upper incisors, first lower premolars, central lower incisors and upper canines were the teeth most
commonly missing. The second upper and lower premolars accounted for 33% of all missing teeth. Ten patients (8.9%) had a verified diagnosis of hypohidrotic ectodermal dysplasia (HED) (Fig. 6) and one patient incontinentia pigmenti. The 10 patients with HED were on average missing 15 teeth (range 6–25). Changes of the facial soft-tissue profile (Fig. 7), listed in Table 1, and dento-alveolar alterations
Fig. 4. Distribution of 112 patients with oligodontia according to gender and number of missing teeth per patient.
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Fig. 5. Location of 1126 missing teeth among 112 patients with oligodontia. Table 1. Characteristic growth disturbances and changes of facial appearance in patients with oligodontia Maxillary retrognathism and hypoplasia Mandibular retrognathism Anterior rotation of mandible Decreased vertical and transversal dimensions of the alveolar process Large inferior extensions of the maxillary sinuses Receding midface Low anterior face height Increased nasal–labial angle Deep labial–mental fold
(Fig. 8), listed in Table 2, were prominent features among these patients with oligodontia. Intermediate treatment Prosthetic
Fig. 6. One of the 10 patients with HED. The 25-year-old patient is missing 17 permanent teeth. (A) Extraorally and (B) intraorally. Note, the atrophic lower alveolar process and the conical crown shape of the right permanent canine.
For functional, but also aesthetic reasons, temporary replacements of missing teeth, i.e. removable dentures, temporary bridges, as well as morphologic changes of maxillary anterior teeth by composite resin restorations were performed. To prevent overeruption of permanent teeth, composite resin build-ups of the antagonizing deciduous teeth or bonding of the permanent teeth were necessary until the final restorations could be inserted.
Fig. 7. (A and B) Characteristic facial profile of two patients with oligodontia missing 18 and 20 permanent teeth, respectively. Orthodontic
Space closure or space reduction combined with extraction of temporary teeth to promote guided eruption of permanent teeth, as well as making and securing space between teeth, according to the
Fig. 8. (A–C) Characteristic dento-alveolar changes in three different patients with oligodontia. Deep bite (A and B), abnormal attrition (A), multiple diastemas (A–C), ectopia (B and C), conical crown shape (A and C), atrophic alveolar ridge (A), impaction of secondary temporary molars (A), steep inclination of incisors (A and B), and overeruption of teeth (A–C).
Treatment of oligodontia Table 2. Dento-alveolar characteristics associated with oligodontia
Table 3. Treatment status of 112 patients with oligodontia
Occlusal disturbances Deep bite Cross bite Steep inclination of maxillary incisors Abnormal attrition
Status
Disturbances of eruption Over eruption of teeth antagonizing hypodontia Impaction of primary molars Ectopic eruption (transposition) Delayed eruption Multiple diastemas Rotation of teeth Alterations of tooth morphology Microdontia Conical shape of incisors and canines
treatment plan, were initiated. Removable appliances were inserted to accomplish bite raising, to correct cross bite, promote sagittal growth of the mandible, and to treat or prevent overeruption and tilting of teeth. Closure of anterior diastemas was sometimes done interceptively on aesthetic indications. Use of palatal implants for orthodontic anchorage was not yet implemented in the intermediate phase in this study group of patients. Surgical
Extraction of temporary teeth was performed for guided mesial eruption of permanent upper molars to replace missing second premolars. Impacted temporary molars were also extracted in some cases in order to preserve bone height of the growing alveolar process and to alleviate full eruption and prevent tilting of neighbouring permanent teeth (Fig. 2B). Treatment
The treatment status of the 112 patients in February 2003 is shown in Table 3. The mean follow-up period of the 51 patients who had finished treatment was 28 months (range 1–68 months). Orthodontic
The type of orthodontic treatment of the 92 patients who had finished treatment or were in some kind of active treatment is shown in Table 4. In patients with very few permanent teeth, temporary or strategic implants were inserted to establish sufficient orthodontic anchorage. Before implant placement, and while implants osseointegrated, retention of the accomplished orthodontic treatment was secured
Finished treatment Ongoing treatment Growth observation Other* Total
No. of patients
%
51 41 8 12
45 37 7 11
112
100
*
Primary teeth still well-functioning, patients have moved from the county, or have chosen not to be treated. Table 4. Orthodontic treatment of 92 patients who have finished or are in active treatment Type of orthodontic treatment
No. of patients
%
Conventional Orthognathic None
57 32 3
62 35 3
Total
92
100
by removable splints, temporary bridges or bonding of teeth. Surgical
The distribution of the different surgical procedures used for the 51 patients with finished treatment and associated complications is listed in Table 5. Major surgical procedures were performed under general anaesthesia. Orthognathic surgery was performed in 14 patients. Of these, five had bimaxillary osteotomies (Fig. 1), four isolated maxillary Le Fort I osteotomies (Fig. 9) and five isolated mandibular sagittal split osteotomies. Two cases of isolated maxillary osteotomy were reoperated due to sagittal and transversal relapse. These two patients had narrow and severe hypoplastic maxillas, and were missing 22 and 23 permanent teeth, respectively. Permanent minor hypoaesthesia of the mental nerve after sagittal split osteotomy occurred in
477
two cases. Sinus floor augmentation was in general performed using a 3:2 mixture of autogenous bone, particulated in a bone mill, and allogenic deproteinized bovine bone (BioOss1, Geistlich, Wolhusen, Switzerland). Augmentation was performed through a lateral opening of the sinus wall and after elevation of the sinus membrane from the sinus floor. When sinus grafting was done simultaneous with a maxillary osteotomy, the sinus membrane was degloved from the sinus floor and fibrin glue (Tisseal1, Immuno, Vienna, Austria) was added to prevent spreading of the augmentation material. In the majority of cases, sinus floor augmentation was done in a preceding procedure at least 3 months earlier. In 12 of the patients sinus floor augmentation was done bilaterally. Augmentation of the alveolar process was done using autogenous cortical bone grafts fixed as on-lays with titanium screws, GTR-procedures using both resorbable and non-resorbable membranes (BioGide1, Geistlich; and Gortex1, W.L. Gore, Flagstaff, AZ, USA), or splitting osteotomies (vertical/horizontal) with a sandwich inlay of bone chips or deproteinized allogenic bone. When pronounced vertical augmentation was needed, osseodistraction of the alveolar process was preferred. Autogenous bone was harvested from the posterior parts of the maxilla, mandibular symphysis area, mandibular ramus, mandibular exostoses, and in five cases from the anterior iliac crest. Inferior alveolar nerve transposition was done simultaneously with sagittal split osteotomy in three patients. In the other six patients nerve transposition was performed as described by ROSENQVIST13. Five patients had bilateral nerve transposition. Nerve transposition caused slight permanent hypoaesthesia of the mental nerve after 4 of the 14 procedures (29%). None of the affected patients have had any problems with this complication.
Table 5. Surgical procedures used for 51 patients who had finished treatment, and rate of associated complications Type of treatment
No. of patients (%)
No. of procedures
Orthognathic surgery Le Fort I osteotomy Sagittal split osteotomy
14 (27%)
19 9 10
Inferior alveolar nerve transposition Sinus lift Bone grafting Implant placement Other*
9 22 37 46 10
*
(18%) (43%) (73%) (90%) (20%)
14 34 96 283 12
Alveolar osseodistraction, vestibular plasty, genioplasty, nasal lift.
No. of complications (%) 2 (22%) 2 (20%) 4 (29%) None Minor bone loss 6 (2%) None
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Fig. 9. Sixteen-year-old patient with 22 missing permanent teeth before (A) and 6.5 years after (B) treatment. (A and B) Frontal views. The patient had a Le Fort I osteotomy with expansion, advancement and impaction of the maxilla, bilateral sinus augmentation, and insertion of 10 dental implants. The bridges were constructed with cantilever extensions in the upper and lower lateral incisor regions. (C) Intraorally, before treatment and (D) after Le Fort I osteotomy, sinus augmentations and extraction of primary teeth, except for the upper second temporary molars. (E) After prosthetic treatment. (F) Orthopanthomogram after finished treatment.
So far, 283 implants have been inserted in 46 patients. Two implant systems were used, Bra˚nemark (Nobel Biocare, Go¨teborg, Sweden) and Astra (Astra Tech, Mo¨lndal, Sweden). Six implants, three in two patients each (2%) were lost, all before abutments were connected. In both patients the implants were placed in anterior maxillary alveolar ridge augmentations. In some cases where implants were inserted either simultaneous with or shortly after extraction of temporary molars, an accelerated resorption of vestibular marginal bone was seen from implant insertion until abutment connection, resulting in visible titanium buccally at the marginal level on the final prosthetic restorations. The number of inserted implants in proportion to the total number of missing teeth in the 51 patients who had finished treatment was 283:536 (53%). Prosthetic
Fixed implant-prosthetic restorations were used in 90% of the patients who had finished treatment (Table 6). Screwretained prosthetic superstructures were chosen when possible. Cantilever units were often used in non-weight-bearing areas with critical mesial-distal space (Fig. 9E and F).
Table 6. Prosthetic treatment of 51 patients who had finished treatment Type of prosthetics
No. of patients
%
Implant-supported single tooth and bridges Conventional bridges Removable partial dentures
46 2 3
90 4 6
Total
51
100
Discussion Epidemiology
Based on previous epidemiological studies2,4,11,15,16, the prevalence of patients with six or more congenitally missing permanent teeth can be estimated to be about 0.1–0.2%. In an area the size of Northern Jutland, Denmark, at least six children with oligodontia should therefore be born on average per year. The number of referred patients in the age group 15–19 years corresponded to a prevalence of 0.1%. In the age group 10–12 years, with five patients per birth cohort referred, the corresponding prevalence was 0.08%. It must be emphasized that the patient material in this study is selected, and no epidemiological conclusions can be drawn. The high average age of 20.5 years of the referred patients, with 28% more than 25 years of age, is probably a temporary phenomenon, and due to an accumulation in the county of adults with oligodontia
with an uncovered requirement for treatment. In the present study, the upper and lower second premolars, followed by the upper first premolars, the upper lateral incisors, the lower central incisors and the upper canines, were the most frequent regions of hypodontia. In other studies of oligodontia2,20 and in several larger epidemiological studies of hypodontia4,7,11,15,16, the upper canines are not reported missing as frequently. As in other studies4,11,15,16,18,19,20, the regions of the upper central incisors, and the upper and lower first molars were only rarely involved. Syndromes with hypodontia/oligodontia
Hypodontia is seen in connection with more than 120 different syndromes, but most frequently with X-linked ectodermal dysplasia8,19, and more rarely in autosomal recessive and dominant forms of HED. In the present study, 10 patients
Treatment of oligodontia (9%) had HED. In a Swedish study2 of 88 patients with eight or more missing teeth, seven patients (8%) had ED and a further six patients had other syndrome diagnoses. In the study by SCHALK-VAN DER WEIDE et al.19 involving 167 selected patients with oligodontia, 48 patients had a verified syndrome diagnosis (25% with ED). From this study19 it is concluded that with a high number of missing teeth, and especially when the upper central incisors and the upper and lower first molars are absent, a possible association with ED should be considered, even in cases with only a discrete expression of the syndrome, as it may be seen in heterozygous females with HED. In the present study, these regions were affected in four of the ten patients with HED, and further in seven other patients, all with severe hypodontia, but without known HED. Since HED is clinically and genetically heterogeneous, an on-going study is being performed to estimate the proportion of possible undiagnosed cases of HED. Organization of management of oligodontia
The low prevalence of patients with oligodontia necessitates a certain degree of centralization of the more complicated cases, if sufficient accumulation of knowledge and experience is to be obtained. With the present number of referred patients, 60–70 patients will continuously be under treatment planning, treatment, coordination of treatment and review appointments. Optimized conditions for the treatment of these patients include a fully integrated interdisciplinary team approach of orthodontists, oral and maxillofacial surgeons, and prosthodontists working under the same roof. So far, the orthodontic and prosthetic treatments are still mainly performed in private practice associated with the centre. Based on collaborative efforts and gained experiences, the following considerations may enhance a more successful treatment outcome in the management of patients with oligodontia.
Reduced vertical growth of the alveolar process should, if possible, be prevented by extraction of impacted primary molars in good time, eventually combined with mesial guided eruption from posterior to the permanent molars, especially in the upper jaw. Cross bite should be eliminated, and sagittal growth of a retrognathic mandible should be promoted. A hypoplastic maxilla with missing lateral incisors should not be closed but opened, and the occlusal plane should be levelled by intrusion and uprighting of steep inclinated and over-erupted incisors. In this way, patients with oligodontia may avoid a deep impact on facial appearance and thus later major surgical interventions. In case orthognathic surgery is not indicated, the final orthodontic treatment needs mainly to focus upon harmonizing the dental arches and securing sufficient space for dental implants. The size of the edentulous space between existing teeth should be precise and in accordance with the planned implant treatment. Bilateral and intermaxillary variations in tooth size (microdontia) may aggravate the space problems. Even small deviations from the plan may result in a compromised situation with insufficient space for implants at the cervical level as well as between roots of adjacent teeth. Uprighting of the adjacent teeth is often critical due to the subsequent implant placement21,22 and to segmentalization of the maxilla during orthognathic surgery. Extrusion of permanent molars, when combined with bite raising, should be postponed until fixed implant–prosthetic constructions have secured the height. The potential of implant anchorage for orthodontic treatment, especially in this group of patients, is high. By this technique it will be possible to close posterior spaces orthodontically6 without retraction of anterior incisors and without compromising the soft-tissue profile. In this way it will be possible not only to reduce the number of implants, but also the number of sinus floor augmentations. Surgical treatment
Orthodontic treatment
Without intermediate treatment patients with oligodontia may end up with steep and over-erupted upper and lower incisors, deep bite, bimaxillary retrognathism, and a hypoplastic and narrow maxilla. Intermediate treatment is therefore of utmost importance to secure and stimulate sagittal, vertical and transversal growth of the jaws, including the alveolar processes.
As outlined in Table 3, this covers a wide spectrum, and the procedures involving bone augmentation, and especially orthognathic surgery, are more demanding in this group of patients. In case several surgical procedures had to be performed in the same patient, general anaesthesia was often used, although fundamentally some of them could have been done under sedation and local anaesthesia.
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Approximately one third of the treatments included orthognathic surgery, due to the hypoplastic growth of the jaws. Information on the treatment options, but also the possible complications are therefore very important at an early stage for treatment planning. With lack of sufficient anchorage and an unstable occlusion, there is a potential risk of relapse after advancement osteotomies, and this may have caused the relapse of two of the maxillary osteotomies. Both patients had very few permanent teeth, and both might have benefited from insertion of implants in a preceding procedure to achieve a more stable peri- and postoperative occlusion. Surgically assisted rapid maxillary expansion should also be considered in a preceding sequence, if severe transverse deficiency and maxillary retrognathia coexists. Relapse after inferior repositioning of the maxilla may be reduced by using a down-sliding osteotomy technique12 which also reduces the need for bone grafting. If closing of space in the upper premolar regions is not done orthodontically it may be performed by advancement of the posterior maxillary segments during Le Fort I osteotomy as an alternative to sinus floor augmentation and subsequent implant treatment. Inferior alveolar nerve transposition, combined with implant insertion, is facilitated when managed simultaneously with a sagittal split osteotomy. In general, nerve transposition is more easily performed in patients with oligodontia due to the often extensive edentulous regions, but neurosensory disturbances have to be expected13. In the present series they were mild and did not cause significant problems to the patients. When sinus floor augmentations are performed in a preceding sequence, before the maxillary osteotomy is done, the sinus membrane is more easily elevated intact, probably due to fewer adhesions. Alternatively, augmentation can be done simultaneously with the maxillary osteotomy, but revascularization of the augmented region may be critical. Displacement of bone chips may occur if uncovered by a sinus membrane. In such cases fibrin glue is a beneficial adjunct. Implants were widely used to replace missing teeth in the present group of patients. Orthodontic, orthognathic, and prosthodontic treatment reduced the number of missing teeth replaced by implants to 53%. At the end of the study period only 2% of the implants had failed to integrate, and none were lost after abutment connection.
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Unless special circumstances indicate the use of implants in adolescents1,5,21,22, they should not be inserted until skeletal growth has finished. Slight continuous eruption of teeth and vertical growth of the alveolar process may proceed, even in adults, after skeletal growth is completed, resulting in infraposition of the implant/ superstructure9,21. Increased vertical resorption of the alveolar process may occur after extraction of deciduous teeth. This should be taken into account when implants are inserted shortly after or simultaneously with extraction of primary teeth to avoid exposure of titanium at the cervical level.
Prosthetic treatment
No more implants than necessary should be inserted, or it may be difficult to achieve a satisfactory aesthetic prosthetic result and natural configuration of the periimplant mucosa. The use of cantilever bridges supported by one or more implants in non-weight-bearing areas, like the lateral upper and lower incisor regions, may be a solution for the frequent space problems in these areas. Screw-retained solutions are to be preferred. Most treatments are performed in young patients and the prosthodontic works may later in life need to be repaired. The vast majority of the prosthetic superstructures in this material were implant borne, but one should not exclude the possibility of using conventional fixed bridges when indicated. Sometimes, this may even spare the patient from a long and sometimes complicated treatment with orthodontics, bone augmentations and implants. It should be noted that conventional bridges have to await pulp retraction in young patients, which may delay the final treatment significantly, and conventional bridges are also very dependent on number and distribution of existing permanent teeth. Patients with more severe oligodontia, with a high number of missing permanent teeth and compromised facial profile, may endure not only functional but also speech problems and psychological distress. It is therefore especially important in such cases to supply clear material information about future treatment goals and the associated time perspective. To promote a higher self esteem and better social acceptance it may also be necessary to insert implants at a young age, and in this way
establish support for temporary fixed or partially fixed prosthetics until the final treatment can be performed later on. From specialization and centralization of treatment follows longer travelling distances for the patients, as well as for their relatives. Most of the patients have to wait several years, often at a critical age, before the final treatment can be performed. A good will to cooperate, confidence and patience are important qualities among the patients, as well as their parents, during this type of long-lasting treatment with multiple patient appointments. References 1. Becktor KB, Becktor JP, Keller EE. Growth analysis of a patient with ectodermal dysplasia treated with endosseous implants: a case report. Int J Oral Maxillofac Implants 2001: 16: 864–874. 2. Bergendahl B, Bergendahl T, Hallonsteen A-L, Koch G, Kurol J, Kvint S. A multidisciplinary approach to oral rehabilitation with osseointegrated implants in children and adolescents with multiple aplasia. Eur J Orthod 1996: 18: 119–129. 3. Bergendahl B, Olgart K. Congenitally missing teeth. In: Koch G, et al: ed. Consensus conference on oral implants in young patients. Jo¨nko¨ping: The Institute for Postgraduate Dental Education 1996: 16–27. 4. Bergstro¨m K. An orthopantomographic study of hypodontia, supernumeraries and other anomalies in schoolchildren between the ages of 8–9 years. An epidemiological study. Swed Dent J 1977: 1: 145–157. 5. Durstberger G, Celar A, Watzek G. Implant-surgical and prosthetic rehabilitation of patients with multiple dental aplasia: a clinical report. Int J Oral Maxillofac Implants 1999: 14: 417–423. 6. Favero L, Brollo P, Bressan E. Orthodontic anchorage with specific fixtures: related study analysis. Am J Orthod Dentofacial Orthop 2002: 122: 84–94. 7. Grahne´n H. Hypodontia in the permanent dentition (Thesis). Odontol Revy 1956: 7(Suppl 3). 8. Hallonsteen A-L, Koch J. Syndromes including tooth agenesis and conditions involving malformations and lost teeth. In: Koch G, et al: ed. Consensus conference on oral implants in young patients. Jo¨nko¨ping: The Institute for Postgraduate Dental Education 1996 : 28–39. 9. Isiri H, Solow B. Continued eruption of maxillary incisors and first molars in girls from 9–25 years, studied by the implant method. Eur J Orthod 1996: 18: 245–256.
10. Nodal M, Kjær I, Solow B. Craniofacial morphology in patients with multiple congenitally missing permanent teeth. Eur J Orthod 1994: 16: 104–109. 11. Ravn JJ, Nielsen LA. En ortopantomografisk undersøgelse af overtal og aplasier hos 1530 Københavnske skolebørn. Tandlaegebladet 1973: 77: 12–22. 12. Reyneke JP, Masureik CJ. Treatment of maxillary deficiency by a Le Fort I downsliding technique. J Oral Maxillofac Surg 1985: 43: 914–916. 13. Rosenquist B. Implant placement in combination with nerve transpositioning: experiences with the first 100 cases. Int J Oral Maxillofac Implants 1994: 9: 522–531. 14. Rune B, Sarna¨s KV. Tooth size and tooth formation in children with advanced hypodontia. Angle Orthod 1974: 44: 316– 321. 15. Rølling S. Hypodontia of permanent teeth in Danish schoolchildren. Scand J Dent Res 1980: 88: 365–369. 16. Rølling S, Poulsen S. Oligodontia in Danish schoolchildren. Acta Odontol Scand 2001: 59: 111–112. 17. Sarna¨s KV, Rune B. The facial profile in advanced hypodontia: a mixed longitudinal study of 141 children with advanced hypodontia. Eur J Orthod 1983: 5: 133–143. 18. SCHALK-VAN DER WEIDE Y. Oligodontia: a clinical, radiographic and genetic evaluation (Thesis). Utrecht: University of Utrecht 1992: 1–106. 19. Schalk-Van Der Weide Y, Beemer FA, Faber JAJ, Bosman F. Symptomatology of patients with oligodontia. J Oral Rehabil 1994: 21: 247–261. 20. Schalk-Van Der Weide Y, Steen WHA, Bosman F. Distribution of missing teeth and tooth morphology in patients with oligodontia. J Dent Child 1992: 59: 133–140. ¨ dman J, Jemt T. Single 21. Thilander B, O implants in the upper incisor region and their relationship to the adjacent teeth. An 8-year follow-up study. Clin Oral Implants Res 1999: 10: 346–355. ¨ dman J, Lekholm U. 22. Thilander B, O Orthodontic aspects of the use of oral implants in adolescents: a 10-year follow-up study. Eur J Orthod 2001: 23: 715–731. Address: Nils Worsaae Department of Oral and Maxillofacial Surgery Glostrup University Hospital Ndr. Ringvej DK-2600 Glostrup Denmark Tel: +45 4323 3208 Fax: +45 4323 3947. E-mail: [email protected]
Invited Review Paper Oro-Facial Rehabilitation
Treatment of severe hypodontia–oligodontia—an interdisciplinary concept
N. Worsaae1, B. N. Jensen2, B. Holm3, J. Holsko4 1 Department of Oral and Maxillofacial Surgery, Glostrup University Hospital, Glostrup, Denmark; 2Department of Oral and Maxillofacial Surgery, Aalborg University Hospital, Aalborg, Denmark; 3Department of Oro-Facial Rehabilitation, School of Dentistry, University of Copenhagen, Copenhagen, Denmark; 4Private Orthodontic Practice, Aalborg, Denmark
N. Worsaae, B. N. Jensen, B. Holm, J. Holsko: Treatment of severe hypodontia– oligodontia—an interdisciplinary concept. Int. J. Oral Maxillofac. Surg. 2007; 36: 473–480. # 2007 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The authors’ experience with oral rehabilitation of patients suffering from oligodontia (i.e. six or more congenitally missing permanent teeth, third molars excluded) is reported. The concept is based on an interdisciplinary team approach involving pedodontists, orthodontists, maxillofacial surgeons and prosthodontists. A series of 112 consecutive patients suffering from oligodontia were referred from 1997 to 2001. Ten of the patients (8.9%) suffered from ectodermal dysplasia. The total number of missing teeth was 1126, with an average of 10 per patient. Ninetytwo patients had either finished treatment or were on an active treatment schedule. Of these, 97% underwent some kind of orthodontic treatment. Of the 112 patients, 51 had finished treatment at the end of the follow-up period (mean 28 months, range 1–68). Of these, fixed implant-supported prosthetic restoration was used in 90% to replace missing teeth, often combined with alveolar ridge augmentations (73%), sinus floor augmentation (43%), inferior alveolar nerve transposition (18%) and orthognathic surgery (27%). Early diagnosis, and comprehensive treatment planning with good coordination and timing of the individual treatment phases are decisive for a successful treatment outcome. The therapeutic concept is presented with special emphasis on surgical aspects.
Hypodontia of permanent teeth, third molars excluded, has a prevalence of about 8%, with an almost equal sex distribution in the Danish population11,15. The prevalence declines with increasing number of missing teeth. RØLLING15 reported only 0.16% of 3325 Danish children with five or more missing permanent teeth. In a recently published study a rate of 0.16% with six or more missing teeth was reported16. In the study by RAVN & NIELSEN11 of 1530 Danish school children, 0.26% had six or more missing teeth. 0901-5027/060473 + 08 $30.00/0
In a Swedish study4 the prevalence of hypodontia was 7.4% with 0.19% missing six or more permanent teeth. SCHALK-VAN DER WEIDE18 defines, in her Dutch study, hypodontia of six or more permanent teeth as oligodontia and estimates the prevalence to be 0.08%. Oligodontia is therefore a relatively rare condition, probably affecting about 0.1–0.2% of the population. Simultaneous with oligodontia are often different positional changes of the existing teeth, their morphology and size14,18,20. Characteristic changes are also growth
Key words: hypodontia; oligodontia; treatment; interdisciplinary. Accepted for publication 25 January 2007 Available online 12 April 2007
disturbances of the maxillofacial skeleton and thus the facial appearance2,10,17. Oligodontia may be associated with other ectodermal abnormalities and syndromes2,3,8,18,19,20. The treatment of patients with oligodontia is therefore often complex. The purpose of this article is to report the authors’ experience with an interdisciplinary, centralized treatment approach to this relatively small group of patients involving pedodontists, orthodontists, prosthodontists and maxillofacial sur-
# 2007 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
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geons. The present study will focus upon treatment planning and the various surgical treatment options in an interdisciplinary context. The more detailed treatment outcome in the longer term will be reported in a subsequent publication.
Demography
The population of Northern Jutland is approximately 500,000 with an actual birth rate of 6000 per year. Previous experience with treatment of patients with multiple missing teeth had emphasized the need for an interdisciplinary collaborative effort. A centre for management of patients with oligodontia was therefore established in 1997 at the Department of Oral and Maxillofacial Surgery, Aalborg University Hospital. Patients with six or
more missing teeth could be referred to the Centre of Hypodontia independent of age. The interdisciplinary concept: conferences and treatment planning
After a primary examination of the patients, the patients are presented at a conference with participation of pedodontist, orthodontist, prosthodontist, and oral and maxillofacial surgeon. Associated specialties are anaesthesiology, paediatrics, genetics, and nuclear and internal medicine. The purpose of the conference is: (1) to establish a treatment plan in agreement with the wishes of the patient (and parents); (2) to evaluate and adjust an on-going treatment schedule according to a previous treatment plan, and follow up on
intermediate treatments in young patients during growth; (3) to evaluate the final outcome of treatment in order to build up team experience for improvement of treatments in the future; (4) to inform patients and parents about consequences of missing teeth, treatment options, and to offer genetic counselling. The clinical and radiographic examinations (Fig. 1), including cephalometric radiographic analysis, orthopantomographic and intraoral radiographs, combined with study casts and diagnostic wax-ups on the casts (Fig. 2), constitute the basic material when treatment planning is performed at the conference. When young patients during growth are presented, an overall treatment schedule
Fig. 1. Treatment planning. Preoperative profile clinically (A and B) and radiographically (D and E) of a 17.5-year-old patient with 13 missing permanent teeth, deep bite, reduced lower facial height, lip eversion and bimaxillary retrognathia. (B and E) Preoperatively but with a simulated, ‘diagnostic’ bite raising and advancement of the paranasal soft tissue by soft retrievable material placed in the anterior upper vestibular sulcus. (C and F) Three years later, after bimaxillary orthognathic surgery, including a down-sliding Le Fort I osteotomy, bilateral sinus lift, but before implant insertion and final prosthetic treatment.
Treatment of oligodontia
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Fig. 2. Study casts before (A) and after (B) wax-up on the casts of a patient with oligodontia missing 12 permanent teeth. The lines indicate the planned orthodontic uprighting of the teeth. Note, the impacted primary molar, the reduced vertical growth of the alveolar process, and the disturbed eruption and tilting of the adjacent teeth.
and planning of the intermediate treatment is outlined. Intermediate treatment is then coordinated with and generally performed in the public health care system. When the orthodontic treatment is finished and the patients have reached an age of 17–18 years, they are rescheduled at a subsequent conference. The patients are then usually ready for planning of the final treatment, i.e. orthognathic surgery, bone augmentations, dental implants and prosthetics. Orthodontic treatment takes place either in the public health care system or in private practice. The surgical treatment, including orthognathic, is performed at the Department of Oral and Maxillofacial Surgery, Aalborg University Hospital. The prosthetic treatment is performed by prosthodontists in private practice. The treatment is financed by public means. Patients
There were 112 patients (54 females, 58 males) with an average age of 20.5 years (range 8–48 years) consecutively referred from July 1997 to March 2001. Children in the public health care system were referred after a diagnosis of oligodontia was established during orthodontic screening procedures, which normally take place at the age of 10–11 years for girls and 11–12 years for boys. Adult persons were referred by private practitioners according to their need for treatment. Many of the adult patients had never had a genuine treatment offer during childhood. The distribution of the 112 patients according to age at the time of referral is shown in Fig. 3. Eighty-one (72%) of the patients were 15 years old or more when referred, and 31 (28%) of the patients were 25 years old or more. The total number of missing teeth of the 112 patients was 1126 (mean: 10 per patient, range 6–25). The distribution of
Fig. 3. Distribution of 112 patients with oligodontia according to age at time of referral.
the 112 patients according to gender and number of missing teeth per patient is presented in Fig. 4. Forty-one patients (37%) were missing 10 or more permanent teeth. The location of the 1126 missing teeth is shown in Fig. 5. The second upper and lower premolars followed by first upper premolars, lateral upper incisors, first lower premolars, central lower incisors and upper canines were the teeth most
commonly missing. The second upper and lower premolars accounted for 33% of all missing teeth. Ten patients (8.9%) had a verified diagnosis of hypohidrotic ectodermal dysplasia (HED) (Fig. 6) and one patient incontinentia pigmenti. The 10 patients with HED were on average missing 15 teeth (range 6–25). Changes of the facial soft-tissue profile (Fig. 7), listed in Table 1, and dento-alveolar alterations
Fig. 4. Distribution of 112 patients with oligodontia according to gender and number of missing teeth per patient.
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Fig. 5. Location of 1126 missing teeth among 112 patients with oligodontia. Table 1. Characteristic growth disturbances and changes of facial appearance in patients with oligodontia Maxillary retrognathism and hypoplasia Mandibular retrognathism Anterior rotation of mandible Decreased vertical and transversal dimensions of the alveolar process Large inferior extensions of the maxillary sinuses Receding midface Low anterior face height Increased nasal–labial angle Deep labial–mental fold
(Fig. 8), listed in Table 2, were prominent features among these patients with oligodontia. Intermediate treatment Prosthetic
Fig. 6. One of the 10 patients with HED. The 25-year-old patient is missing 17 permanent teeth. (A) Extraorally and (B) intraorally. Note, the atrophic lower alveolar process and the conical crown shape of the right permanent canine.
For functional, but also aesthetic reasons, temporary replacements of missing teeth, i.e. removable dentures, temporary bridges, as well as morphologic changes of maxillary anterior teeth by composite resin restorations were performed. To prevent overeruption of permanent teeth, composite resin build-ups of the antagonizing deciduous teeth or bonding of the permanent teeth were necessary until the final restorations could be inserted.
Fig. 7. (A and B) Characteristic facial profile of two patients with oligodontia missing 18 and 20 permanent teeth, respectively. Orthodontic
Space closure or space reduction combined with extraction of temporary teeth to promote guided eruption of permanent teeth, as well as making and securing space between teeth, according to the
Fig. 8. (A–C) Characteristic dento-alveolar changes in three different patients with oligodontia. Deep bite (A and B), abnormal attrition (A), multiple diastemas (A–C), ectopia (B and C), conical crown shape (A and C), atrophic alveolar ridge (A), impaction of secondary temporary molars (A), steep inclination of incisors (A and B), and overeruption of teeth (A–C).
Treatment of oligodontia Table 2. Dento-alveolar characteristics associated with oligodontia
Table 3. Treatment status of 112 patients with oligodontia
Occlusal disturbances Deep bite Cross bite Steep inclination of maxillary incisors Abnormal attrition
Status
Disturbances of eruption Over eruption of teeth antagonizing hypodontia Impaction of primary molars Ectopic eruption (transposition) Delayed eruption Multiple diastemas Rotation of teeth Alterations of tooth morphology Microdontia Conical shape of incisors and canines
treatment plan, were initiated. Removable appliances were inserted to accomplish bite raising, to correct cross bite, promote sagittal growth of the mandible, and to treat or prevent overeruption and tilting of teeth. Closure of anterior diastemas was sometimes done interceptively on aesthetic indications. Use of palatal implants for orthodontic anchorage was not yet implemented in the intermediate phase in this study group of patients. Surgical
Extraction of temporary teeth was performed for guided mesial eruption of permanent upper molars to replace missing second premolars. Impacted temporary molars were also extracted in some cases in order to preserve bone height of the growing alveolar process and to alleviate full eruption and prevent tilting of neighbouring permanent teeth (Fig. 2B). Treatment
The treatment status of the 112 patients in February 2003 is shown in Table 3. The mean follow-up period of the 51 patients who had finished treatment was 28 months (range 1–68 months). Orthodontic
The type of orthodontic treatment of the 92 patients who had finished treatment or were in some kind of active treatment is shown in Table 4. In patients with very few permanent teeth, temporary or strategic implants were inserted to establish sufficient orthodontic anchorage. Before implant placement, and while implants osseointegrated, retention of the accomplished orthodontic treatment was secured
Finished treatment Ongoing treatment Growth observation Other* Total
No. of patients
%
51 41 8 12
45 37 7 11
112
100
*
Primary teeth still well-functioning, patients have moved from the county, or have chosen not to be treated. Table 4. Orthodontic treatment of 92 patients who have finished or are in active treatment Type of orthodontic treatment
No. of patients
%
Conventional Orthognathic None
57 32 3
62 35 3
Total
92
100
by removable splints, temporary bridges or bonding of teeth. Surgical
The distribution of the different surgical procedures used for the 51 patients with finished treatment and associated complications is listed in Table 5. Major surgical procedures were performed under general anaesthesia. Orthognathic surgery was performed in 14 patients. Of these, five had bimaxillary osteotomies (Fig. 1), four isolated maxillary Le Fort I osteotomies (Fig. 9) and five isolated mandibular sagittal split osteotomies. Two cases of isolated maxillary osteotomy were reoperated due to sagittal and transversal relapse. These two patients had narrow and severe hypoplastic maxillas, and were missing 22 and 23 permanent teeth, respectively. Permanent minor hypoaesthesia of the mental nerve after sagittal split osteotomy occurred in
477
two cases. Sinus floor augmentation was in general performed using a 3:2 mixture of autogenous bone, particulated in a bone mill, and allogenic deproteinized bovine bone (BioOss1, Geistlich, Wolhusen, Switzerland). Augmentation was performed through a lateral opening of the sinus wall and after elevation of the sinus membrane from the sinus floor. When sinus grafting was done simultaneous with a maxillary osteotomy, the sinus membrane was degloved from the sinus floor and fibrin glue (Tisseal1, Immuno, Vienna, Austria) was added to prevent spreading of the augmentation material. In the majority of cases, sinus floor augmentation was done in a preceding procedure at least 3 months earlier. In 12 of the patients sinus floor augmentation was done bilaterally. Augmentation of the alveolar process was done using autogenous cortical bone grafts fixed as on-lays with titanium screws, GTR-procedures using both resorbable and non-resorbable membranes (BioGide1, Geistlich; and Gortex1, W.L. Gore, Flagstaff, AZ, USA), or splitting osteotomies (vertical/horizontal) with a sandwich inlay of bone chips or deproteinized allogenic bone. When pronounced vertical augmentation was needed, osseodistraction of the alveolar process was preferred. Autogenous bone was harvested from the posterior parts of the maxilla, mandibular symphysis area, mandibular ramus, mandibular exostoses, and in five cases from the anterior iliac crest. Inferior alveolar nerve transposition was done simultaneously with sagittal split osteotomy in three patients. In the other six patients nerve transposition was performed as described by ROSENQVIST13. Five patients had bilateral nerve transposition. Nerve transposition caused slight permanent hypoaesthesia of the mental nerve after 4 of the 14 procedures (29%). None of the affected patients have had any problems with this complication.
Table 5. Surgical procedures used for 51 patients who had finished treatment, and rate of associated complications Type of treatment
No. of patients (%)
No. of procedures
Orthognathic surgery Le Fort I osteotomy Sagittal split osteotomy
14 (27%)
19 9 10
Inferior alveolar nerve transposition Sinus lift Bone grafting Implant placement Other*
9 22 37 46 10
*
(18%) (43%) (73%) (90%) (20%)
14 34 96 283 12
Alveolar osseodistraction, vestibular plasty, genioplasty, nasal lift.
No. of complications (%) 2 (22%) 2 (20%) 4 (29%) None Minor bone loss 6 (2%) None
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Fig. 9. Sixteen-year-old patient with 22 missing permanent teeth before (A) and 6.5 years after (B) treatment. (A and B) Frontal views. The patient had a Le Fort I osteotomy with expansion, advancement and impaction of the maxilla, bilateral sinus augmentation, and insertion of 10 dental implants. The bridges were constructed with cantilever extensions in the upper and lower lateral incisor regions. (C) Intraorally, before treatment and (D) after Le Fort I osteotomy, sinus augmentations and extraction of primary teeth, except for the upper second temporary molars. (E) After prosthetic treatment. (F) Orthopanthomogram after finished treatment.
So far, 283 implants have been inserted in 46 patients. Two implant systems were used, Bra˚nemark (Nobel Biocare, Go¨teborg, Sweden) and Astra (Astra Tech, Mo¨lndal, Sweden). Six implants, three in two patients each (2%) were lost, all before abutments were connected. In both patients the implants were placed in anterior maxillary alveolar ridge augmentations. In some cases where implants were inserted either simultaneous with or shortly after extraction of temporary molars, an accelerated resorption of vestibular marginal bone was seen from implant insertion until abutment connection, resulting in visible titanium buccally at the marginal level on the final prosthetic restorations. The number of inserted implants in proportion to the total number of missing teeth in the 51 patients who had finished treatment was 283:536 (53%). Prosthetic
Fixed implant-prosthetic restorations were used in 90% of the patients who had finished treatment (Table 6). Screwretained prosthetic superstructures were chosen when possible. Cantilever units were often used in non-weight-bearing areas with critical mesial-distal space (Fig. 9E and F).
Table 6. Prosthetic treatment of 51 patients who had finished treatment Type of prosthetics
No. of patients
%
Implant-supported single tooth and bridges Conventional bridges Removable partial dentures
46 2 3
90 4 6
Total
51
100
Discussion Epidemiology
Based on previous epidemiological studies2,4,11,15,16, the prevalence of patients with six or more congenitally missing permanent teeth can be estimated to be about 0.1–0.2%. In an area the size of Northern Jutland, Denmark, at least six children with oligodontia should therefore be born on average per year. The number of referred patients in the age group 15–19 years corresponded to a prevalence of 0.1%. In the age group 10–12 years, with five patients per birth cohort referred, the corresponding prevalence was 0.08%. It must be emphasized that the patient material in this study is selected, and no epidemiological conclusions can be drawn. The high average age of 20.5 years of the referred patients, with 28% more than 25 years of age, is probably a temporary phenomenon, and due to an accumulation in the county of adults with oligodontia
with an uncovered requirement for treatment. In the present study, the upper and lower second premolars, followed by the upper first premolars, the upper lateral incisors, the lower central incisors and the upper canines, were the most frequent regions of hypodontia. In other studies of oligodontia2,20 and in several larger epidemiological studies of hypodontia4,7,11,15,16, the upper canines are not reported missing as frequently. As in other studies4,11,15,16,18,19,20, the regions of the upper central incisors, and the upper and lower first molars were only rarely involved. Syndromes with hypodontia/oligodontia
Hypodontia is seen in connection with more than 120 different syndromes, but most frequently with X-linked ectodermal dysplasia8,19, and more rarely in autosomal recessive and dominant forms of HED. In the present study, 10 patients
Treatment of oligodontia (9%) had HED. In a Swedish study2 of 88 patients with eight or more missing teeth, seven patients (8%) had ED and a further six patients had other syndrome diagnoses. In the study by SCHALK-VAN DER WEIDE et al.19 involving 167 selected patients with oligodontia, 48 patients had a verified syndrome diagnosis (25% with ED). From this study19 it is concluded that with a high number of missing teeth, and especially when the upper central incisors and the upper and lower first molars are absent, a possible association with ED should be considered, even in cases with only a discrete expression of the syndrome, as it may be seen in heterozygous females with HED. In the present study, these regions were affected in four of the ten patients with HED, and further in seven other patients, all with severe hypodontia, but without known HED. Since HED is clinically and genetically heterogeneous, an on-going study is being performed to estimate the proportion of possible undiagnosed cases of HED. Organization of management of oligodontia
The low prevalence of patients with oligodontia necessitates a certain degree of centralization of the more complicated cases, if sufficient accumulation of knowledge and experience is to be obtained. With the present number of referred patients, 60–70 patients will continuously be under treatment planning, treatment, coordination of treatment and review appointments. Optimized conditions for the treatment of these patients include a fully integrated interdisciplinary team approach of orthodontists, oral and maxillofacial surgeons, and prosthodontists working under the same roof. So far, the orthodontic and prosthetic treatments are still mainly performed in private practice associated with the centre. Based on collaborative efforts and gained experiences, the following considerations may enhance a more successful treatment outcome in the management of patients with oligodontia.
Reduced vertical growth of the alveolar process should, if possible, be prevented by extraction of impacted primary molars in good time, eventually combined with mesial guided eruption from posterior to the permanent molars, especially in the upper jaw. Cross bite should be eliminated, and sagittal growth of a retrognathic mandible should be promoted. A hypoplastic maxilla with missing lateral incisors should not be closed but opened, and the occlusal plane should be levelled by intrusion and uprighting of steep inclinated and over-erupted incisors. In this way, patients with oligodontia may avoid a deep impact on facial appearance and thus later major surgical interventions. In case orthognathic surgery is not indicated, the final orthodontic treatment needs mainly to focus upon harmonizing the dental arches and securing sufficient space for dental implants. The size of the edentulous space between existing teeth should be precise and in accordance with the planned implant treatment. Bilateral and intermaxillary variations in tooth size (microdontia) may aggravate the space problems. Even small deviations from the plan may result in a compromised situation with insufficient space for implants at the cervical level as well as between roots of adjacent teeth. Uprighting of the adjacent teeth is often critical due to the subsequent implant placement21,22 and to segmentalization of the maxilla during orthognathic surgery. Extrusion of permanent molars, when combined with bite raising, should be postponed until fixed implant–prosthetic constructions have secured the height. The potential of implant anchorage for orthodontic treatment, especially in this group of patients, is high. By this technique it will be possible to close posterior spaces orthodontically6 without retraction of anterior incisors and without compromising the soft-tissue profile. In this way it will be possible not only to reduce the number of implants, but also the number of sinus floor augmentations. Surgical treatment
Orthodontic treatment
Without intermediate treatment patients with oligodontia may end up with steep and over-erupted upper and lower incisors, deep bite, bimaxillary retrognathism, and a hypoplastic and narrow maxilla. Intermediate treatment is therefore of utmost importance to secure and stimulate sagittal, vertical and transversal growth of the jaws, including the alveolar processes.
As outlined in Table 3, this covers a wide spectrum, and the procedures involving bone augmentation, and especially orthognathic surgery, are more demanding in this group of patients. In case several surgical procedures had to be performed in the same patient, general anaesthesia was often used, although fundamentally some of them could have been done under sedation and local anaesthesia.
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Approximately one third of the treatments included orthognathic surgery, due to the hypoplastic growth of the jaws. Information on the treatment options, but also the possible complications are therefore very important at an early stage for treatment planning. With lack of sufficient anchorage and an unstable occlusion, there is a potential risk of relapse after advancement osteotomies, and this may have caused the relapse of two of the maxillary osteotomies. Both patients had very few permanent teeth, and both might have benefited from insertion of implants in a preceding procedure to achieve a more stable peri- and postoperative occlusion. Surgically assisted rapid maxillary expansion should also be considered in a preceding sequence, if severe transverse deficiency and maxillary retrognathia coexists. Relapse after inferior repositioning of the maxilla may be reduced by using a down-sliding osteotomy technique12 which also reduces the need for bone grafting. If closing of space in the upper premolar regions is not done orthodontically it may be performed by advancement of the posterior maxillary segments during Le Fort I osteotomy as an alternative to sinus floor augmentation and subsequent implant treatment. Inferior alveolar nerve transposition, combined with implant insertion, is facilitated when managed simultaneously with a sagittal split osteotomy. In general, nerve transposition is more easily performed in patients with oligodontia due to the often extensive edentulous regions, but neurosensory disturbances have to be expected13. In the present series they were mild and did not cause significant problems to the patients. When sinus floor augmentations are performed in a preceding sequence, before the maxillary osteotomy is done, the sinus membrane is more easily elevated intact, probably due to fewer adhesions. Alternatively, augmentation can be done simultaneously with the maxillary osteotomy, but revascularization of the augmented region may be critical. Displacement of bone chips may occur if uncovered by a sinus membrane. In such cases fibrin glue is a beneficial adjunct. Implants were widely used to replace missing teeth in the present group of patients. Orthodontic, orthognathic, and prosthodontic treatment reduced the number of missing teeth replaced by implants to 53%. At the end of the study period only 2% of the implants had failed to integrate, and none were lost after abutment connection.
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Unless special circumstances indicate the use of implants in adolescents1,5,21,22, they should not be inserted until skeletal growth has finished. Slight continuous eruption of teeth and vertical growth of the alveolar process may proceed, even in adults, after skeletal growth is completed, resulting in infraposition of the implant/ superstructure9,21. Increased vertical resorption of the alveolar process may occur after extraction of deciduous teeth. This should be taken into account when implants are inserted shortly after or simultaneously with extraction of primary teeth to avoid exposure of titanium at the cervical level.
Prosthetic treatment
No more implants than necessary should be inserted, or it may be difficult to achieve a satisfactory aesthetic prosthetic result and natural configuration of the periimplant mucosa. The use of cantilever bridges supported by one or more implants in non-weight-bearing areas, like the lateral upper and lower incisor regions, may be a solution for the frequent space problems in these areas. Screw-retained solutions are to be preferred. Most treatments are performed in young patients and the prosthodontic works may later in life need to be repaired. The vast majority of the prosthetic superstructures in this material were implant borne, but one should not exclude the possibility of using conventional fixed bridges when indicated. Sometimes, this may even spare the patient from a long and sometimes complicated treatment with orthodontics, bone augmentations and implants. It should be noted that conventional bridges have to await pulp retraction in young patients, which may delay the final treatment significantly, and conventional bridges are also very dependent on number and distribution of existing permanent teeth. Patients with more severe oligodontia, with a high number of missing permanent teeth and compromised facial profile, may endure not only functional but also speech problems and psychological distress. It is therefore especially important in such cases to supply clear material information about future treatment goals and the associated time perspective. To promote a higher self esteem and better social acceptance it may also be necessary to insert implants at a young age, and in this way
establish support for temporary fixed or partially fixed prosthetics until the final treatment can be performed later on. From specialization and centralization of treatment follows longer travelling distances for the patients, as well as for their relatives. Most of the patients have to wait several years, often at a critical age, before the final treatment can be performed. A good will to cooperate, confidence and patience are important qualities among the patients, as well as their parents, during this type of long-lasting treatment with multiple patient appointments. References 1. Becktor KB, Becktor JP, Keller EE. Growth analysis of a patient with ectodermal dysplasia treated with endosseous implants: a case report. Int J Oral Maxillofac Implants 2001: 16: 864–874. 2. Bergendahl B, Bergendahl T, Hallonsteen A-L, Koch G, Kurol J, Kvint S. A multidisciplinary approach to oral rehabilitation with osseointegrated implants in children and adolescents with multiple aplasia. Eur J Orthod 1996: 18: 119–129. 3. Bergendahl B, Olgart K. Congenitally missing teeth. In: Koch G, et al: ed. Consensus conference on oral implants in young patients. Jo¨nko¨ping: The Institute for Postgraduate Dental Education 1996: 16–27. 4. Bergstro¨m K. An orthopantomographic study of hypodontia, supernumeraries and other anomalies in schoolchildren between the ages of 8–9 years. An epidemiological study. Swed Dent J 1977: 1: 145–157. 5. Durstberger G, Celar A, Watzek G. Implant-surgical and prosthetic rehabilitation of patients with multiple dental aplasia: a clinical report. Int J Oral Maxillofac Implants 1999: 14: 417–423. 6. Favero L, Brollo P, Bressan E. Orthodontic anchorage with specific fixtures: related study analysis. Am J Orthod Dentofacial Orthop 2002: 122: 84–94. 7. Grahne´n H. Hypodontia in the permanent dentition (Thesis). Odontol Revy 1956: 7(Suppl 3). 8. Hallonsteen A-L, Koch J. Syndromes including tooth agenesis and conditions involving malformations and lost teeth. In: Koch G, et al: ed. Consensus conference on oral implants in young patients. Jo¨nko¨ping: The Institute for Postgraduate Dental Education 1996 : 28–39. 9. Isiri H, Solow B. Continued eruption of maxillary incisors and first molars in girls from 9–25 years, studied by the implant method. Eur J Orthod 1996: 18: 245–256.
10. Nodal M, Kjær I, Solow B. Craniofacial morphology in patients with multiple congenitally missing permanent teeth. Eur J Orthod 1994: 16: 104–109. 11. Ravn JJ, Nielsen LA. En ortopantomografisk undersøgelse af overtal og aplasier hos 1530 Københavnske skolebørn. Tandlaegebladet 1973: 77: 12–22. 12. Reyneke JP, Masureik CJ. Treatment of maxillary deficiency by a Le Fort I downsliding technique. J Oral Maxillofac Surg 1985: 43: 914–916. 13. Rosenquist B. Implant placement in combination with nerve transpositioning: experiences with the first 100 cases. Int J Oral Maxillofac Implants 1994: 9: 522–531. 14. Rune B, Sarna¨s KV. Tooth size and tooth formation in children with advanced hypodontia. Angle Orthod 1974: 44: 316– 321. 15. Rølling S. Hypodontia of permanent teeth in Danish schoolchildren. Scand J Dent Res 1980: 88: 365–369. 16. Rølling S, Poulsen S. Oligodontia in Danish schoolchildren. Acta Odontol Scand 2001: 59: 111–112. 17. Sarna¨s KV, Rune B. The facial profile in advanced hypodontia: a mixed longitudinal study of 141 children with advanced hypodontia. Eur J Orthod 1983: 5: 133–143. 18. SCHALK-VAN DER WEIDE Y. Oligodontia: a clinical, radiographic and genetic evaluation (Thesis). Utrecht: University of Utrecht 1992: 1–106. 19. Schalk-Van Der Weide Y, Beemer FA, Faber JAJ, Bosman F. Symptomatology of patients with oligodontia. J Oral Rehabil 1994: 21: 247–261. 20. Schalk-Van Der Weide Y, Steen WHA, Bosman F. Distribution of missing teeth and tooth morphology in patients with oligodontia. J Dent Child 1992: 59: 133–140. ¨ dman J, Jemt T. Single 21. Thilander B, O implants in the upper incisor region and their relationship to the adjacent teeth. An 8-year follow-up study. Clin Oral Implants Res 1999: 10: 346–355. ¨ dman J, Lekholm U. 22. Thilander B, O Orthodontic aspects of the use of oral implants in adolescents: a 10-year follow-up study. Eur J Orthod 2001: 23: 715–731. Address: Nils Worsaae Department of Oral and Maxillofacial Surgery Glostrup University Hospital Ndr. Ringvej DK-2600 Glostrup Denmark Tel: +45 4323 3208 Fax: +45 4323 3947. E-mail: [email protected]