Missing anterior teeth: orthodonticclosure and transplantation asviable options to conventionalreplacementsARILD STENVIK & BJORN U. ZACHRISSON

Introduction

Traditional replacement options for missing maxillary

incisors include implants and partial dentures.

Although less well known among endodontists and

general dentists, orthodontic space closure and auto-

transplantation of developing premolars may, however,

constitute relevant alternatives.

The challenge in treating patients with missing max-

illary incisors and concomitant malocclusion is how to

achieve the best esthetic and functional results, particu-

larly in the long term (1). Although data for survival of

single tooth implants is favorable, over time there may be

significant problems associated with their use in the

esthetic zone, such as infraocclusion (2, 3), gingival

retraction with root exposure, and darkening of the

overlying gingiva due to resorption of the buccal bone

plate (4). Autotransplantation of teeth and orthodontic

space closure represent viable biological approaches for

replacement of incisors because of the permanence of the

result, particularly in growing individuals.

Treatment decisions for young people with missing

incisors should be based on a comprehensive assessment

that includes several factors (1), and the ultimate

treatment plan should be dictated by the diagnosis and

not by a preferred methodology. From 2000 to 2003,

the authors published a series of articles in the American

Journal of Orthodontics and Dentofacial Orthopedics on

the outcome of tooth transplantation, and of orthodontic

space closure in the management of missing teeth (5–9).

It is clear from the debate that followed (3, 10–16) that

there are conflicting opinions, pointing to a need for

further information and research in this area.

The purpose of this article is to summarize the

authors’ experience over the past 40 years with

transplantation and orthodontic space closure in the

treatment of missing incisors. There are two main

reasons for missing incisors in young people: traumatic

injuries and congenital absences. Because the nature of

the problems differs in these two situations, the

management with regards to the two types of missing

teeth will be discussed separately.

Loss of incisors from traumaticinjuries

Traumatic injuries may affect one or more maxillary

incisors as well as other oral tissues. The treatment plan in

each situation will depend on factors such as the number

of missing teeth, the status of the remaining

teeth, possible concerns about the occlusion, space

availability, age, facial morphology, growth pattern, and

tooth morphology (1). From a preventative perspective,

persons with protruding incisors are at risk for

dental injuries (17) and may therefore need orthodontic

treatment irrespective of whether teeth are missing

or not.

Indications for autotransplantation

More than 30 years ago, Slagsvold & Bjercke (18)

established a method of transplanting teeth with

41

Endodontic Topics 2006, 14, 41–50All rights reserved

Copyright r Blackwell Munksgaard

ENDODONTIC TOPICS 20081601-1538

incompletely developed roots. After transplantation,

the root growth in such teeth continues and they

maintain their capacity for functional adaptation (Fig. 1).

Endodontic treatment is generally not necessary, and

the long-term survival and success rates are high (5).

Slagsvold & Bjercke (19) also discussed the indications

for replacing missing incisors by transplanting devel-

oping premolars. This produces a normal root, but the

crown will, however, need to be reshaped with either

composite resin or porcelain laminate veneer (PLV) to

fit esthetically into its new arch position (Figs 1f, g and

2b, c, e, f).

An important prerequisite for transplantation is a

donor tooth with 2/3 to 3/4 root length that can be

sacrificed without detrimental effects to the donor site.

Careful surgery to avoid any damage to the surface of

the root is essential. The treatment plan must take into

account the need for orthodontic intervention pre- and

post-transplantation by:

� creating sufficient space at the recipient site;

� managing the residual space at the donor site

(usually comprised of orthodontic space closure);

� correcting the malocclusion, if any; and

� orthodontic adjustment of the transplanted tooth’s

position to achieve an optimal esthetic result.

Premolars are usually the preferred graft because

dental injuries frequently happen at the time when

premolar root development has still not been com-

pleted, root morphology is favorable by being straight

and conical, and the extraction space may be utilized to

relieve crowding. The morphology of the lower first

premolar in particular provides a good opportunity for

the restorative dentist to simulate maxillary incisor

morphology by a minimally-invasive recontouring and

veneering approach. The palatal cusp of a transplanted

premolar may be ground into dentin (20) and covered

with porcelain or resin to protect against pulpal injury

from plaque.

Indications for orthodontic space closure

The maxillary central incisor is the most frequently

avulsed tooth, and the following conditions favor

orthodontic space closure:

� overjet, open bite, proclined incisors;

� general crowding;

� large lateral incisors, small canines;

� adjacent healthy teeth;

� young individuals, vertical facial growth direction;

and

� general need and desire for orthodontic treatment.

If more than one tooth is missing in the same

quadrant, orthodontic space closure alone usually

cannot resolve the situation. A combination of

orthodontic tooth movement and tooth transplanta-

tion may be used (Fig. 2).

Treatment

One maxillary central incisor missing

If the missing tooth is to be replaced by autotrans-

plantation, the timing of treatment is determined by

root development of the donor tooth. The surgical

positioning of the transplant is to some degree dictated

by the bone volume at the recipient site. A bony socket

Fig. 1. Accidental loss of left maxillary central incisor (a–c). The missing tooth was replaced by autotransplantation of amandibular second premolar (d, f). Root development continued after the transplantation, and the pulp canalobliterated in the part of the root that was formed before the transplantation (d, e, g–i). Endodontic treatment is notnecessary, and the long-term prognosis for the restored ‘new’ central incisor is excellent.

Stenvik & Zachrisson

42

has to be made which adapts and covers the root to

ensure an optimal prognosis for the transplanted tooth.

This implies that there may be a need to adjust the

position of the transplant before the crown is reshaped

to simulate incisor morphology (Fig. 2).

When orthodontic space closure is the preferable

alternative, treatment may be started immediately if the

central incisor is avulsed in the early mixed dentition

(Fig. 3). The treatment principles include the follow-

ing:

� move lateral incisor to the midline immediately

upon loss of central;

� extract upper second deciduous molars to guide

first permanent molars mesially;

Fig. 2. Following traumatic loss of two adjacent maxillary incisors (right central and lateral incisors), the mandibularright second premolar was autotransplanted to the position of the missing central incisor (a, b). The transplanted toothwas reshaped to incisor morphology by a temporary composite resin build-up (c). The remaining spaces were closedorthodontically and the malocclusion was corrected (d). Then, the build-up on the transplanted premolar was replacedwith a porcelain veneer (e, f). Also the canine (C) and right first premolar (P) were restored with porcelain veneers to animproved lateral incisor and canine morphology, respectively (e, f).

Fig. 3. Orthodontic space closure after traumatic loss of the maxillary right central incisor in an 8-year-old boy (a). Theremaining teeth were moved mesially (b) and their vertical positions were adjusted by making arch-wire bends (c) toobtain more harmonious gingival margins (d). The lateral incisor (L), canine (C), and first premolar (P) were restored byporcelain veneers or composite resin build-ups (e). Multi-stranded wires have been bonded for long-term retention (f).

Orthodontic closure and transplantation as options to conventional replacements

43

� extract deciduous canine to change the eruption

path of the permanent canine (Figs 4 and 5); and

� completion of orthodontic treatment in the early

permanent dentition.

The approach to treatment (21) is illustrated in Fig. 3.

Depending on occlusion and space conditions, compen-

satory extractions may be necessary (see Table 1).

Attention to detail during treatment is important; at

the end of treatment, midlines should coincide, the

mesialized lateral should be upright with the gingival

margin at the same level as the natural central incisor, and

the reshaped crown should have the same morphology

and color as the in situ adjacent central incisor (Fig. 3e).

More than one incisor missing

When two maxillary central incisors are missing, the space

may be managed by moving both laterals mesially

according to the principles above (Figs 4 and 5). For

more comprehensive injuries, a combination of tooth

transplantation and orthodontic space management may

be appropriate (Figs 2 and 6). Careful planning and

timing of treatment will then be necessary and inter-

disciplinary team-work from an early stage is important.

Teeth and bone are missing

Severe injuries to the oral region may lead to bony

fractures and alveolar bone loss (Fig. 6), which may

represent a serious obstacle to the rehabilitation of the

patient. Teeth have the potential to induce formation of

alveolar bone, and this potential can be used to an

advantage both by tooth transplantation and ortho-

dontic tooth movement. The re-establishment of a

normal alveolar process by the movement of tooth

transplants is demonstrated in Figs 1, 2, and 6. Another

Fig. 4. Accidental loss of both maxillary central incisors in a young boy. Early orthodontic movement (a) of the lateralincisors to the midline (b) resulted in a marked change in the eruption path of the canines to a more mesial position.

Fig. 5. Avulsion of both maxillary central incisors by traumatic injury. Early orthodontic movement (a) of the lateralincisors resulted in mesial eruption of the canines (b). A second phase of orthodontic treatment was started aftereruption of the premolars and remaining spaces were closed (c–e). Facial appearance before and after treatment (f).

Stenvik & Zachrisson

44

option is to move teeth into an area with insufficient

bone for placement of an implant. The implant may

then be inserted in the initial position of the tooth that

has been moved (22).

Results

Systematic analysis of the result after transplantation

of premolars to replace incisors has demonstrated

Table 1. Orthodontic treatment after loss of maxillary incisors: some typical solutions

Teeth missing

Movement of

anterior teeth

Diagnosis and indications Treatment

Occlusion Space, protrusion

Compensatory

extraction Molar occlusion

One central

incisor

Lateral to

replace central

Class I (neutro-

occlusion)

1. Crowding in upper,

good lower arch

1 maxillary premolar Change to distal

2. As (1) plus

atypical/weak lateral

1 maxillary lateral Change to distal

3. Bimaxillary

protrusion and

crowding

1 maxillary and

2 mandibular

premolars

Keep in neutral

4. As (3) plus

atypical/weak

lateral

1 maxillary lateral

and 2 mandibular

premolars

Keep in neutral

5. Anterior teeth in

good position

None Change to distal

one side

Class II, div. 1

(overjet, disto-

occlusion)

1. Upper crowding 1 maxillary premolar Keep in distal

2. As (1) plus

atypical/weak

lateral

1 maxillary lateral Keep in distal

Two central

incisors

Laterals to

replace centrals

Class I (neutro-

occlusion)

1. Crowding

upper and lower

arch

2 mandibular

premolars

Keep in neutral

2. Crowding upper,

good lower arch

None Change to distal

Class II, div. 1

(overjet, disto-

occlusion)

1. Crowding upper

and lower arch

2 mandibular

premolars

Change to neutral

2. Crowding upper,

good lower arch

None Keep in distal

Four incisors Canines to replace

laterals, other

replacement

for centrals

Class II, div. 1

(overjet, disto-

occlusion)

1. Crowding upper,

good lower arch

None Keep in distal

2. Crowding upper

and lower

2 mandibular

premolars

Transplantation?

Change to neutral

From Stenvik & Zachrisson, 1993 (1).

Orthodontic closure and transplantation as options to conventional replacements

45

long-term (425 years) survival rates of more than 90%

(23, 24). Publications from teams in Scandinavia (25)

and Japan (26) contain examples of premolars success-

fully transplanted to replace incisors. We found that

compared with natural incisors, the overall status of the

transplanted premolars and surrounding tissues is similar

(6). The esthetic results were also generally satisfactory

(7), particularly when adjunctive orthodontic treatment

ensured optimal positioning of the transplant (Fig. 2b–f).

When patients expressed dissatisfaction, the reason

usually was related to the suboptimal appearance of the

composite resin build-ups being made to reshape the

lateral incisor to the central incisor shape and color.

Teamwork with the restorative dentist is therefore

important, and meticulous attention to detail should be

exercised at all stages of treatment.

Congenitally missing maxillary lateralincisors

Indications for orthodontic space closure

Several factors should be considered in the assessment

of indications for orthodontic space closure, including

Fig. 6. Mandibular fractures, loss of four teeth and alveolar bone after injury. Trauma at the age of 10 resulted infracture of the mandibular body and condyles, open bite, and loss of maxillary right central and lateral incisors (a, b).Left central incisor and right first premolar had to be extracted later because of pulp necrosis and ankylosis. Crowding inthe posterior segments allowed for transplantation of premolars: the left maxillary second premolar to the area of theright first premolar, the mandibular left second premolar replaced the maxillary right central incisor, and the mandibularright first premolar replaced the maxillary left central incisor (c, d, f). Occlusion and tooth position were correctedorthodontically. The premolars transplanted to the incisor area were restored to incisor morphology by composite resinbuild-ups (d, f). The alveolar bone that had been lost because of the injury (e) was re-established when the transplantedteeth were moved orthodontically into the area and thus induced development of new bone (c, f).

Stenvik & Zachrisson

46

amount of crowding and spacing, size and shape of the

teeth, and the occlusal relationships. Transplantation of

teeth is rarely indicated for absent lateral incisors. The

indications for space closure are summarized by Rosa &

Zachrisson (27, 28):

� a tendency toward maxillary crowding;

� a well-balanced profile and normally inclined

incisors;

� canines and premolars of similar size;

� dentoalveolar protrusion;

� Class II molar occlusion; and

� mandibular crowding or protrusion.

Mesial drift of the canines during eruption frequently

takes place, and this may represent an additional

indication because the distribution of spaces may

prevent replacement of lateral incisors by restorative

methods. If orthodontic measures need to be initiated

anyway, spaces may just as well be closed by mesial

movement of teeth (27, 29) (Figs 7 and 8).

If only one lateral incisor is missing, removal of the

contralateral incisor that is present may sometimes lead

to improvement of the final result. The indications for

extraction may include peg-shaped and diminutive

teeth, severe crowding, and improved prognosis for

obtaining symmetry and coinciding midlines. If the

lateral incisor present is of, or can be made to,

acceptable size and shape, unilateral space closure may

be attempted (Fig. 8).

Fig. 7. Congenital absence of both maxillary lateral incisors (a). After orthodontic space closure, the canines werereshaped to incisor morphology by incisal grinding and composite resin build-ups (b, c). The first premolars wereintruded (d) during orthodontic treatment for improved marginal gingival levelling and to allow incisal composite resinbuild-ups (e). A different case (f) demonstrates gingival leveling (arrows) simply by selective bracket positioning on thefirst premolar and canine.

Fig. 8. A young girl with congenitally missing right maxillary incisor and peg-shaped left lateral incisor before (a) and 10years after orthodontic treatment (b). The right canine was moved to the position of the lateral incisor and re-shaped bygrinding and composite resin build-up. The peg tooth was kept and provided with a porcelain veneer. The long-termresult is esthetically satisfactory.

Orthodontic closure and transplantation as options to conventional replacements

47

Treatment

Guidelines for management of orthodontic space

closure for missing lateral incisors were proposed by

Tuverson in 1970 (29), and are still valid. Successful

treatment of patients with missing lateral incisors

requires attention to a number of details:

� The difference in crown torque (inclination)

between the lateral incisor and canine: sufficient

lingual root torque of the canine is important (Fig.

8), otherwise it may look unnatural in the position

of the lateral incisor.

� The size difference between lateral incisors, canines,

and premolars: this may result in ‘lateral incisors’

appearing too wide and long and ‘canines’ that are

too small and narrow. This may be prevented by

extrusion and grinding of the canines (20), and

intrusion of premolars and composite resin build-

up of the labial cusp (27) (Fig. 7d, e). By selective

bracket placement, the desired movement can be

‘built’ into the orthodontic appliance (Fig. 7f).

� Functional occlusion: long-term follow-up studies

demonstrate no functional occlusion or TMJ

problems in space closure patients (30, 31).

Apparently the presence or absence of a canine rise

is not related to periodontal status, and there is no

evidence that a Class I canine relationship is the

preferred mode of treatment.

� Contouring of canines/color: with today’s techni-

ques in esthetic restorative dentistry, it is possible to

transform a maxillary canine such that it has a

naturally looking lateral incisor morphology (Figs

2, 3, 7 and 8). This may include orthodontic

extrusion for gingival leveling, incisal grinding and

interproximal stripping, composite resin ‘corners’,

vital bleaching of yellowish canines, and PLVs.

� Retention and relapse: there is usually a marked

tendency for reopening of spaces in the anterior

maxilla, and therefore long-term retention with

bonded multi-stranded wire retainers over four to

six teeth should routinely be applied (Fig. 3f).

Clinical implications

Only a few systematic studies examining the results of

space closure for missing maxillary lateral incisors are

available (8, 30, 31). The results are encouraging, both

from a biological and functional perspective. In addition,

a number of treated patients have been presented in case

reports (20, 27–29, 32–34), demonstrating that ex-

cellent esthetic results may be obtained. The most

common arguments against orthodontic space closure

have been related to the esthetic result and the potential

lack of a canine-protected occlusion during function.

These challenges can now be overcome by attention to

detail in planning and treatment as discussed above.

Space conditions and occlusal relationships may

sometimes make closure of all spaces unrealistic. An

alternative may then be to open space in the posterior

segments for single-tooth implants or bridges. This

approach will have the same biological advantages in

the anterior part of the maxilla as normal space closure

and may provide better long-term stability. Restora-

tions in the posterior area of the maxilla do not have to

meet the same strict esthetic requirements as those in

the anterior area. If implants are selected as the

replacements for the missing teeth, they will get a

favorable axial loading. As discussed elsewhere (4), a

critical factor in implant therapy is the long-term

appearance of the soft tissue surrounding the replace-

ment, such as the risk for gingival recession, dark

margins, and lack of satisfactory gingival papilla

contour. In the anterior maxilla, such outcomes may

be detrimental to the overall esthetic result, but they are

much less troublesome in the posterior areas.

So far no studies are available examining the overall

costs of orthodontic space closure compared with other

alternatives from a long-term perspective. The validity

of prospective studies is complicated by the continuous

introduction of new methods and technology. This

applies both to the restorative and orthodontic

disciplines. As an example, space management in

orthodontics may in the future be facilitated by the

use of mini-screws, providing absolute anchorage.

Discussion and conclusion

The most evident advantage of replacing missing

incisors with the patient’s own teeth, either by

transplantation or orthodontic space closure, is the

permanence and biological compatibility of the treat-

ment result. At the end of treatment, normal gingival

tissues and papillae will surround all teeth. Even when

PLVs are needed in young patients, such restorations

can be made shortly after the surgical and orthodontic

treatment. Only a minimal amount of enamel is

removed during preparation and there is little risk of

Stenvik & Zachrisson

48

pulp damage. This is important because the majority of

patients presenting with missing incisors due to trauma

or agenesis are children and adolescents. If treatment is

postponed or spaces are opened, young patients have to

wait until completion of facial growth before receiving

their final restoration. During the interim period,

which may last several years, the patient will have to

wear either a removable or fixed resin-bonded tempor-

ary prosthesis.

Evidence-based clinical practice for the management

of missing anterior teeth should be established from

data on the functional and esthetic clinical result of

various treatment modalities, as well as costs in the

long-term. No such data are currently available. One of

the reasons may be the difficulties in collecting samples

of sufficient size for follow-up and analysis. The

frequency of missing maxillary lateral incisors is about

1%, and the incidence of dental injuries is o2%

annually, of which only 3–4% may be considered to be

severe. Optimal results also require integrated inter-

disciplinary teamwork, which further complicates the

collection of research data.

Even if solid comparative research data for the different

replacement methods so far are not available, our

experience indicates that orthodontic space closure and

transplantation of teeth can produce treatment results

that are almost indistinguishable from an intact dentition.

The goal should be that patients who have received

treatment for missing teeth will have treatment results

that are indistinguishable from normal appearance. A

prerequisite is that the therapy is based on a complete

diagnosis, that the indications for the selected approach

are present, and that attention to detail throughout

treatment is exercised by all involved in the treatment.

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