hypodontia by almuzian

university of glasgow

Orthodontic management of hypodontia

.

Mohammed Almuzian

1/1/2013

.

Table of Contents

Definition............................................................................................................2

Classification......................................................................................................2

Prevalence...........................................................................................................3

Aetiology............................................................................................................4

Clinical presentation...........................................................................................5

Features ..............................................................................................................5

Management.......................................................................................................6

Multidisciplinary team .......................................................................................6

Indications for Treatment...................................................................................7

Factors to be considered in the management of hypodontia...............................7

Sequence of treatment.........................................................................................7

Treatment options...............................................................................................8

Space opening & space maintenance................................................................10

Advantages.......................................................................................................10

Disadvantage.....................................................................................................10

Mechanics.........................................................................................................10

Space closing or partial space closure to reduce extent of prostheses..............11

Indication..........................................................................................................11

Advantages.......................................................................................................12

Disadvantages...................................................................................................12

Mechanics.........................................................................................................13

Orthodontic appliances used in hypodontia cases............................................14

Mohammed Almuzian, 2013 1

Difficulties in orthodontic mechanotherapy of hypodontia..............................14

Retention regimes.............................................................................................15

Restorative options for space replacement.......................................................16

Temporary in-treatment replacement...............................................................16

Long term replacement.....................................................................................16

Techniques to increase the amount of bone at area of hypodontia for implant

insertion............................................................................................................22

Advantages and disadvantages of build-up small teeth before, during or after

orthodontic treatment........................................................................................23

Factors affect the choice of the prosthesis to restore the space........................24

Treatment option for missing lower premolars................................................25


Orthodontic management of hypodontia

Key articles (Carter et al., 2003; Savarrio & McIntyre, 2005, Kokich 1997)

Definition

1. The term hypodontia is generally used to describe developmental tooth

absence excluding the third molars (Goodman et al., 1994). Hypodontia may

be sub-classified according to its severity, as mild (1–2 missing teeth) almost

80%, moderate (3–5 missing teeth almost 10%) or severe (≥6 missing teeth

almost 1%). (Larmour 2005, Naini et al., 2011)

Classification

A. According to the number of teeth involved (Goodman et al., 1994).

1.Hypodontia refers to a lack of 1-6 teeth, excluding third molars

2.Oligodontia (sever hypodontia) refers to a lack of more than six teeth,

excluding third molars Hobkirk et al., 1995

3.Anodontia refers to a complete absence of teeth in one or both dentitions. Very

rare

B. According to the inheritance pattern (Wright et al., 1993).

1. Non-syndromic hypodontia

A. Nonsyndromic hypodontia can be subclassified according to method of

occurrences (Burzynski and Escobar, 1983):

Familial or Inherited. This form can follow autosomal dominant, autosomal

recessive or autosomal sex-linked patterns of inheritance, with considerable

variation in both penetrance and expressivity.

Sporadically 33% of hypodontia cases


B. Non-syndromic hypodontia can be sub-classified according to teeth involved

and their number:

1.Localized incisor–premolar hypodontia (OMIM 106600), which affects only

one or a few of these teeth. This is the most common form and is seen in

around 8% of Caucasians (Nieminen et al, 1995).

2.Oligodontia (OMIM 604625) occurs in around 0.25% of Caucasians and can

involve all classes of teeth (Sarnas & Rune, 1983).

C. Candidate genes for nonsyndromic human hypodontia (Vastardis et al., 1996;

Lammi et al., 2004; Suda et al., 201, Cobourne, 2007, Han et al., 2008):

MSX1 associated with premolar and lateral incisors. Usually associated with

sever hypodontia.

EDA gene mutations usually includes the loss of mandibular and/or maxillary

incisors and canines

PAX9. Associated with molars.

AXIN2 which is mainly associated with Finnish family hypodontia.

2. Syndromic hypodontia

Seen in association with Down syndrome, ectodermal dysplasia, CCDS, CLP &

CP , Van de Wound syndrome, Rieger and Book syndrome. Larmour 2005,

Shapira et al., 2000), (Kerwetzki and Homever, 1974; Marković,

1982b; Parsche et al., 1990), (Uthoff, 1989).

Candidate genes MSX1 (MSX1 represents a candidate gene for both syndromic

and nonsydromic hypodontia).

Prevalence

Wide range of prevalence because of the geographic and ethical variation

1. Dentition:


A. Deciduous teeth 0.1 – 0.9 % (1-9 in 1000) with the maxillary then mandibular

lateral incisors being most commonly missing. As a rule, when the primary

tooth is missing, its permanent counterpart will also be absent (Hall, 1983).

B. In permanent dentition, 4-6% excluding 8s (Grahnen, 1956). Polder 2004 4.6%

male and 6.4% in female

(Localized incisor–premolar hypodontia around 8% of Caucasians (Nieminen et

al, 1995)

Oligodontia occurs in around 0.25% of Caucasians (Sarnas & Rune, 1983).

2. Ethnic variation

• Ethnic variation exists, (Endo et al, 2006a; Buenviaje and Rapp, 1984; Zhu et

al, 1996; Polder et al, 2004).

• The incidence of missing permanent teeth, excluding the third molar, is 3.4 per

cent in Swiss children, 4.4 per cent in American children, 4.6 per cent in Israeli

children, 6.1 per cent in Swedish children, 8 per cent in Finnish children, and

9.6 per cent in Austrian children (Thilander and Myrberg, 1973; Brook,

1974; Aasheim and Ögaard, 1993; Slavkin, 1999).

• The common missing tooth types in Caucasians being lower second premolars

> upper lateral incisors > upper second premolars > lower central incisors

Larmour 2005.

• In some Asian populations, lower central incisors are reported to be commonly

missing.

3. Gender

• F:M = 3:2 (Larmour, 2005, (RØLling, 1980)

4. Teeth series

• As a general rule, if only one or a few teeth are missing, the absent tooth will

be the most distal tooth of any given type (Jorgenson, 1980; Schalk van der

Weide et al., 1994).

5. Location:

• Lower > upper (RØLling, 1980)


• Left > right Wisth et al., 1974 (RØLling, 1980) but other show the opposite

(Fekonja, 2005)

6. Teeth affected:

• 25-35% of all third molars

• Lower premolars most commonly absent and mainly symmetrical (2.6%)

(RØLling, 1980).

• Missing laterals: 2% More bilaterally than unilaterally. Familial tendency

associated with peg contralateral laterals incisors and palatally impacted

canines. It represents 20% of the hypodontia cases (Bren et al).

• Lower incisor 0.2% of Caucasians but more common in Asian.

• U3s developmentally absent 3's: 0.08% (Bren et al)

• First and second molars, is rare (Simons et al, 1993).

• The overall prevalence of peg-shaped maxillary permanent lateral incisors was

1.8%. he prevalence rates were higher among Mongoloid people, orthodontic

patients, and women. Although the prevalence of unilateral and bilateral lateral

incisors was the same, the left side was twice as common as the right side.

Subjects with unilateral peg-shaped maxillary permanent lateral incisors might

have a 55% chance of having lateral incisor hypodontia on the contralateral

side.Hue et al meta-analysis 2013.

Aetiology of Hypodontia

A. Genetic

1. Familial hypodontia: (Brook , 2002) Hypodontia prevalence was higher

in first-degree relatives (22%) of hypodontia index cases than in the general

population (4.4%), there is a threshold in hypodontia so that:

Below threshold microdont teeth

Above threshold missing tooth


2. Genetic regression: over evolution from mammalian dentition to primate

dentition, we lost teeth ie dogs have 3 incisors in each quadrant; we as human

have 2 incisors only.

B. Environmental (Graber, 1978)

I. Systemic disruption of Dental Lamina : eg. Ectodermal dysplasia

disturbance of all the tissue developing from the outer layer (ectoderm)

of the foetus due

chemo

radiotherapy

infection

low birth weight

drugs

hormonal

II. Localised disruption of Dental Lamina : eg. Cleft of alveolus results in

transection of the dental lamina.

III. Nutritional Deprivation : environmental regression if you don’t feed

properly (Ca), teeth will suffer. But in Africa there is starvation yet the

frequency of missing teeth is less than that seen in the Western

population. Other enviromenal causes are infection, radiation. Larmour

2005

C. Polygenetic inheritance (Suarez and Spence 1974)

Clinical presentation or sign of hypodontia (Dhanrajani, 2002)

1. Delayed eruption.

2. Asymmetrical eruption

3. Bazar tooth form (Brook 1984)

4. Infraocclusion

5. Retained primaries

6. Absent primaries


7. Lack of alveolar bone growth

Al-Abdullah et al 2015 concluded that tooth agenesis isolated to the maxilla is

frequently associated with microdontia of the maxillary lateral incisors, whereas

tooth agenesis isolated to the mandible is frequently associated with retained

deciduous molars, infraoccluded deciduous molars, and impacted teeth. The

results of this study may provide additional evidence supporting the field-

specific genetic control theory for dental development in both jaws.

Features of hypodontia cases (Larmour, 2005, Cobourne, 2007)

A. Skeletal feature (depending on the severity of hypodontia)

1. Retrognathic and hypoplastic maxilla. Wisth 1974

2. Small MMPA and reduced vertical dimensions. Woodworth 1985

B. Alveolar features

1. Lack of alveolar bone (Guckes, 2002)

2. There is often a fairly flat palatal vault which results in reduced

anchorage capacity of upper removable appliances, Nance palatal crib or

implant placement.

C. Occlusal features (Fekonja, 2005 #410)

1. Upright incisors

2. Increased overbite.

D. Dental features

1.Delayed and asymmetric eruption of permanent teeth. The second premolars are

particularly prone to delays in dental development and may not be visible

radiographically until the age of 9 years. Hence, a diagnosis of their absence

should be made with caution before this age. Wisth et al., 1974

2.Prolonged retention of primary teeth (Kurol, 1984)(Nunn, 2003)

3.Infra-occlusion of primary teeth (Kurol, 1984)


4.Ectopic eruption or impaction of the adjacent teeth particularly maxillary

canines. Up to 5% of those with absent lateral incisors may be complicated by

maxillary canine impaction. (Brin 1986)

5.Adjacent teeth

Microdontia (Brook 1984)

Conical crown. Brook 1984

Transposition Peck 1993

Enamel hypoplasia. Brook 1984

Molar taurodontism: This is a developmental anomaly where the roots of the

molars are shortened with elongated pulp chamber. The roots of taurodont

teeth may be more prone to orthodontically related root resorption and they

offer less anchorage because of their reduced surface area. Additionally,

endodontic treatment and extractions may be complicated by the abnormal root

morphology. Seow 1989

Management of hypodontia

Multidisciplinary team for hypodontia treatment (Larmour, 2005)

1.Clinical nurse coordinator

2.Orthodontist

3.Restorative dentist

4.Paediatric and prosthodontics dentist

5.Oral surgeon

6.General dental practitioner

7.Geneticist

Indications for Treatment (Shaw 1980, 1981)

1. Aesthetics


2. Functional

3. Dental rehabilitation

4. Dental health problems

Food impaction due to tipped or drifted teeth

Traumatic OB

Infraoccluded primary teeth

Factors to be considered in the management of hypodontia

(Carter & Gillgrass, 2003 (Dhanrajani, 2002)

1.Age: Younger preferred because OB can be corrected and stability better, also

PD problem and caries become an issue in adult

2.Severity As the number of absent teeth increases the treatment option of space

closure becomes unrealistic.

3.Facial profile

4.Intra-arch relationship (crowding or spacing)

5.Inter-arch relationship (dynamic and static relationship)

6.Shape, size and colour of the adjacent teeth

7.Smile and gingival line

8.Clinical situation of the primary and permanent teeth

9.Patient's opinion and co-operation

10.Clinician philosophy

Sequence of treatment

Kokich and Spear, 1997

1. Orthodontists and restorative dentists establish realistic objectives rather

than idealistic

2. Create a diagnostic set-up and Kesling set up (the two are different from

each other)


3. Determine the sequence of orthodontic treatment

4. Build-up malformed teeth,

Where should the maxillary lateral incisor be positioned mesiodistally relative

to the central incisor and canine? Should be more space bet 2 and 3

Where should the lateral incisor be positioned buccolingually: toward the labial,

in the center of the ridge, or toward the lingual? Depend on the type and

thickness of final restoration

Where should the lateral incisor be positioned incisogingivally? This

relationship is determined by the position of the gingival margins

5. Evaluate gingival esthetic

6. Provision space to facilitate restorative treatment

7. Take progress radiographs, and measure the space with Strowman T

ruler.

8. Sometimes silcon trays to evaluate the space

9. Occlusal adjustment

10. Interact during finishing

Treatment options

A. Treatment for hypodontia in primary dentition

No treatment is indicated at this stage. However removable dentures for

psychological and functional reasons might be used but it will require regular

adjustments during growth. Retention and stability may be problematic in

those with poorly developed alveolar ridges.(Fekonja, 2005)(Tarjan, 2005)

B. Mixed dentition

1.Involve mainly the interceptive treatment

Extract 1o tooth early allow space closure. Some recommend extracting

primary tooth, allowing permanent teeth to erupt and close space, then reopen


space at adulthood, so by this way we preserve the bone. Lindqvist, 1980

Other IO treatment involve:

I. RFM when class III problem is present.(Kircelli, 2006)

II. Guided eruption

III. Diastema closure

IV. Space management.

V. Serial extraction

VI. IO for impacted canine.

VII. Composite build-ups to improve aesthetics of microdont permanent teeth or

worn deciduous teeth

2.Retain primary tooth:

As long as possible & replace with prosthesis after cession of the growth, this

will help in preserving alveolar bone

Permanently, retain the primary tooth (if the Es survive until 20yrs then they

appear to have a good prognosis for long term survival Bjerklin &

Bennett,2000)

MissingClass I Class II Class III

2 If closing space xtn

E to allow mesial drift

of buccal segments

Space can be used as

part of treatment

Space should be

preserved and

regained to allow

proclination

lower 5 Xtn LE early (9yrs) to

allow mesial drift

Keep LE as long as

possible lower arch

should be as big as

possible

May be used as part of

xnt to treat

malocclusion

C. Treatment for hypodontia in permanent dentition. Hobkirk et al., 1995

1. Accept


2. Restorative treatment without orthodontic either by implant, bridge,

transplantation, teeth build-up or by retaining primary teeth with alteration in

the shape or size by build-up, premolarization or hemisection and slicing.

3. Combined planning, orthodontics/restorative opinions necessary and

sometime surgery might be involved in severe cases. This involve the

following options:

A. Space opening or space maintenance

Advantages space opening (Tarjan, 2005)

1. Improved aesthetics specially if the adjacent of poor shape and colour

2. Improved function

3. Space closure may be slower than normal and may not be possible to

close the space completely. Asher & Lewis, 1986

Disadvantage space opening

Commits the patient to a permanent prosthesis

Mechanics

1. Before treatment combine treatment planning with trial wax set ups

2. The amount of space required is determined according to:

Standard tooth size

Golden proportion

Contra-lateral sizes

Bolton analysis (this only applied if we have one tooth type missing)

Restorative opinion according to the future restorative prosthesis.

3. Fixed appliances — for 3dimensional tooth control

4. 'Push-pull' mechanics — eg. involving open coil spring in the 2 region

(the 'push') and lacebacks to retract the canine (the 'pull')


5. Use tipedge braket or wire bending or bracket positioning to correct root

parallisim

6. Once appropriate space has been opened, closed-coil spring or an acrylic

denture tooth attached to the orthodontic archwire via a bonded bracket should

be placed:

To maintain space

To restore aesthetic.

7. In case of missing E, premolarization of the E is recommended to mimic

the 5s, but only if the root configuration and morphology of the E allowed that

without compromising the pulpal health.

8. Retention — VFRs (can prevent relapse in all 3 dimensions) or Hawley-

type retainer incorporating prosthetic teeth and wire stops mesial and distal to

the acrylic tooth.

Space closing and canine substitution

Indication (Kinzer & Kokich 2005)

1. Macro aesthetic factors:

Profile: After one of the two occlusal criteria has been satisfied, the

profile should be evaluated. Generally, a balanced, relatively straight

profile is ideal. However, a mildly convex profile also may be acceptable

A patient with a moderately convex profile, retrusive mandible, and a

deficient chin prominence may not be an appropriate candidate for canine

substitution.

Type of malocclusion (crowding and incisor relationship): There are

two types of malocclusions that permit canine substitution. The first is an

Angle class II malocclusion with no crowding in the mandibular arch.

The second alternative is an Angle class I malocclusion with sufficient

crowding to necessitate mandibular extractions.in class III condition


opening the space for lateral incisors will cause wagon wheel effect and

make the placement of the implant more difficult.

2. Mini aesthetic factors: Canine shape and color: The ideal lateral

incisor substitute is a canine that is the same color as the central incisor, is

narrow at the CEJ buccolingually and mesiodistally, and has a relatively flat

labial surface and narrow mid-crown width buccolingually.

3. Micro aesthetic factors: Gingival and lip level: If the patient has an

excessive gingiva-to-lip distance on smiling, the gingival levels will be more

visible. Also, in patients with high smile lines, a prominent canine root

eminence could also be an esthetic concern

Advantages

1. No prosthetic replacement (Tuverson 1970)

2. Better stability (Tuverson 1970, Robertsson, 2000)

3. Better periodontal health in the long term if 3 replaces 2 rather than

using prostheses and no TMD problems. (Robertsson & Mohlin, 2000,

Robertsson, 2000, Senty 1976)

4. Better aesthetic. Rosa et al (1998) and Robertsson, 2000 suggest ways

in which the orthodontist in combination with the restorative dentist can make

space closure a more attractive alternative.

5. Excellent acceptance by patients. Turpin 2004 showed that space

closure has better outcome in TMJ, and PD health and patient satisfaction.

Disadvantages

1. Facial aesthetic: incisors might be retracted and affect the facial

profile by flattening it. Sergl and Stodt 1970

2. Dental aesthetic:

ML shift in unilateral hypodontia (Robertsson, 2000)

Un-aesthetic canine replacing lateral regarding colour, size and shape.

Zachirsson and Thilander 1985


Unsightly gingival architecture, which tends to worsen with age. Zachirsson and

Thilander 1985

Constriction of the dental arch and dark buccal corridor. Angle 1907

Bolton discrepancy. Therefore, a critical step in the patient-selection process is

the completion of a diagnostic wax-up. This enables the orthodontist and

dentist to evaluate the final occlusion, measure how much canine reduction is

necessary, and determine if an aesthetic final result is achievable. Bolton 1967

3. Functionally: loss of canine guidance and TMD. Thomas 1967,

(Robertsson, 2000)

4. Mechanically: space difficult to close. (Cameron, 1996)

5. Retention: prolonged retention required. (Carter, 2003)

Mechanics

1. Before treatment

Combine treatment planning with trial wax set ups. Asher & Lewis, 1986

Sometime in unilateral missing of incisors, the contralateral might be extracted

for symmetrical purposes

2. Set up stage

Invert 3 bracket or bond 2 bracket to the 3 — will torque the 3 root palatally,

reducing the 3 eminence and locate the 3 root similar to the position that

should have been occupied by the 2. Rosa & Zachrisson, 2001

Bond 3 bracket on the 4 tooth with (Shroff et al., 1996)

A. More distal position to get mesio-labial rotation of the 4 (good aesthetics

because the palatal cusp will be hidden and the 4 will appear wider

mesiodistally) and in order to allow the 4 to use more space MD and also help

in avoiding premature contact with lower during function.

B. More occlusal position to get intrusion of the 4 and then build it up, this

might help in reducing the palatal cusp interference with the lower canine and

move the gingival line of the 4 more apically to simulate the 3s.


3 extrusion to allow the gingival margin to be positioned more incisally to

mimic that of the 2 with gradual selective grinding (apply Durphat after each

cession of grinding). As they erupt, a thicker portion of the crown comes into

contact with the mandibular incisors. This often causes prematurities that must

be equilibrated periodically during the alignment stage of orthodontic

treatment. Thordarson et al.,1991

3. Anchorage wise

Use reverse pull HG or TAD if necessary to close spaces in a mesial direction.

Yanosky & Holmes,2008

The space might be used as a way to correct the malocclusion like crowding or

increased OB. Goodman et al., 1994

4. Finishing

Selective grinding of the 3 tips

Selective grinding of 3 cingulum to avoid interferences

Bleaching of the dark 3s.

Build up the buccal cusp of the intruded 4s.

The problem of reshaping by selective grinding might expose more dentine

causing sensitivity and darkness of the tooth.

5.Retention Bonded wire retainer+VFR or removable appliance. Goodman et

al., 1994

Orthodontic appliances used in hypodontia cases

1. Removable appliances are very useful in the management of hypodontia

cases for the following purposes:

• For overbite reduction,

• Tipping movements

• For space maintenance in the upper arch (Retainers).

2. Fixed appliances are otherwise almost always the appliance of choice as

they allow greater control of tooth movement .


3. Orthodontic-surgical approach

4. Combination

Difficulties and challenges in orthodontic mechanotherapy of hypodontia

1. OH: Patients with hypodontia, with their tendency to microdontia, may

be more at risk of plaque accumulation between bracket and gingiva caused by

their close proximity, and may need specific oral hygiene advice and

preventive measures to avoid these undesirable consequences.

2. Bracket bonding and fitness: due to altered tooth morphology, with

altered enamel structure and microdontia.

3. Long spans of unsupported arch wire

4. Anchorage consideration

5. Aligning stage: Up righting and aligning teeth specially rotated teeth

6. Levelling stage: Overbite reduction in the absence of a stable occlusal

stop. (by URA, functional appliance or Dalh appliance, intrusion mechanics in

adult or in high MMPA or orthognathic surgery)

7. Space closure stage: Space closure in the absence of crowding is

difficult

8. Root resorption: Patients with moderate to severe hypodontia have also

been shown to be more susceptible to apical root resorption. This is due to:

Unusual root morphology

Long treatment

Extensive tooth movements required

Microdontia that result in short inter-bracket span and heavier forces.

Genetic correlation.

9. Retention and stability. Due to certain unstable movement


Retention regimes for hypodontia

1. Long term part-time wear of a removable retainer, a removable

retainer is fitted which carries acrylic teeth and wire stops. The retainer can

also conveniently include a flat anterior bite plane to encourage further

overbite reduction and increase the inter-occlusal space to facilitate the

provision of the definitive restoration

2. Bonded retainer after all diastema ac closure.

3. Adhesive bridge like a cast metal Maryland design can be considered

supplied with VFR for 6 months followed by night time wear for at least a

further 6 months. Survival rate is 80% over 6 years.

4. Adjunctive procedure:

• IPS

• CSF

• Over correction of the rotation

• If a rotated tooth is to be used as an abutment, either a second abutment must

be included in the bridge to prevent rotational relapse or include multiple teeth

as bridge abutments to prevent the undesirable drifting and relapse that may

occur if a single cantilevered pontic is used.

Restorative options for space replacement

Temporary in-treatment replacement

1) Prosthetic tooth and labial bracket

2) Prosthetic tooth and acrylic flange cantilever

3) Prosthetic tooth attached directly to the

archwire: indicated when the underlying tooth is

impacted and the plan is extrude it while the acrylic


tooth in place. A step in the AW can be made to provide more accessibility.

The aim is to avoid the bracket thickness.

4) Extracted tooth: When extraction of a tooth is enforced, and the coronal

tissue remains intact and not discoloured, use of the tooth itself can be an ideal

choice of in-treatment replacement

Long term replacement

1) Removable Prostheses

2) Fixed Prostheses

3) Implant

4) Autotransplantation

In details

1.Removable Prostheses

Acrylic

Co/Cr

Overdentures in patient with microdontia.

VFR with tooth + composite droplet same like invislaign to control the bodily

position of the tooth. Better to give the pt two retainer one with tooth during

the day the other at night without tooth to allow healing of the gum.

Indications and advantages

1. Poor OH and high caries rate.

2. Medical contraindication for fixed options

3. Children who still growing;

4. Temporary solution

5. When adjacent teeth not suitable for fixed prosthesis


6. Insufficient bone for Implants;

7. Numerous teeth missing.

Advantages

1. Simple to construct.

2. No preparation of natural teeth.

3. Appearance of prosthetic teeth can be extremely natural.

4. Can restore missing/deficient hard and soft tissue as well as missing

teeth.

5. Can act as retainers.

Disadvantages

1. Bulk

2. Gradual wear of prosthetic teeth

3. Gradual alteration in supporting tissues

4. Psychological opposition to removable prosthesis

2.Adhesive Fixed

Advantages

1. Fixed restoration (could be metal fused to ceramic or full porcelain)

2. Could be cantilever or fixed fixed RBB.

3. Used in any age

4. Relatively simple to construct

5. Preparation of natural teeth required is relatively conservative, confined

to enamel only

6. Potential for temporary retention of post-orthodontic tooth position. If the

plan to use the bridge as a temporary measure until implant becomes sensible,


then RBB without preparation is indicated as a reversible method and the

patient should be warned about a potential need for alveolar grafting before

implant. However, because of continued facial growth and compensatory tooth

eruption, several years can elapse between completion of orthodontic treatment

for a teenage patient and implant placement. There are reports by Olsen &

Kokich in 2010 that, after successful orthodontic opening of the implant space,

the central incisor and canine roots reapproximate in 11% of cases during

retention and prevent implant placement. To ensure sufficient space for

implant placement, Olsen & Kokich in 2010 recommended at least 6.3 mm of

intercoronal space and 5.7 mm of interradicular space between the adjacent

central incisor and canine. A bonded wire or resin-bonded bridge will help to

reduce root approximation that might occur during retention, some prefer to

put implant if the pt is 18+ while he or she in the active orthodontic treatment

7. Hussey 1996 show that 88% remained bonded over 3 years using

cantilever RBB.

8. Garnett 2006 showed that success rate almost good (80%) over 59

months.

9. Heather 2009 (systematic view) suggests that RBBs have an 87.7

percent five-year survival rate—are a treatment alternative to

conventional bridges and implant-supported crowns.

10. Pjetursson 2007 estimated these alternatives to have a 87.7% over 5

years.

11. Garrett 2007 showed that Bristol bridge has good success rate.

Disadvantages

1. Potential for debond

2. Potential instability of teeth if prosthesis is also being used for retention

3. Difficult to cope with spaced teeth

4. Potential for caries


5. May complicate oral hygiene measures

6. Visible metal retainers 'grey-out' from metal backing

NB: Cantilever bridge has a better success. This can be explained by the fact

that the teeth with an intact periodontal ligament (i.e. not ankylosed) have an

inherent mobility. So, each tooth will move in and out of the socket and in a

vertical direction under masticatory load. The amount of mobility and overall

direction of movement depends on the size of the root and amount of

periodontal ligament (support and width), and the position of the tooth in the

arch. If the teeth are joined together via a restoration (a bridge, a splint), they

still retain their own underlying mobility, and it is this which can be

responsible for teeth becoming debonded from restorations. This factor has to

be taken into consideration when designing fixed restorations which are meant

to retain teeth in position, since any failure can be followed by unwanted tooth

movement.) The addition of rest to hold the other adjacent tooth to help in

retention is advisable.

3.Fixed-Fixed Prostheses


No paralisim of roots

Edentulous span is short;

No enough bone for implant

Medical contraindication

Financial issue

Advantages

Fixed

Possible to make minor changes in relative sizes and alignment of

abutment/pontic teeth


Potential for retention of post-orthodontic tooth position,

Disadvantages

Cost

Preparation of abutment teeth. Literature varies but may be up to 10% loss of

vitality of abutments previously presumed vital 10 years after preparation

(Karlsson, 1986)

May complicate oral hygiene

Difficult to cope with spaced teeth

Failure rate

4. Implant

Implant treatment is normally deferred until the jaws have stopped growing, to

avoid related problems, typically in the very late teens or early 20s (Nordquist

and McNeill, 1975; Ödman et al., 1988; Oesterle et al., 1993; Robertsson and

Mohlin, 2000; Rosa and Zachrisson, 2001).

The orthodontics can be useful facility with implant service by:

1) Controlling the space for implant (open and reduce the space). Research

suggests a minimum of 1mm between implant and natural tooth to allow

adequate healing and adequate papilla development. With the standard width

of an implant platform being 4mm, this means at least 6mm must be created to

ensure adequate room for placement.

2) Change root angulation

3) Prepare the peri-implant site by developing a new bone (if the alveolus is

narrow or the sinus is low)



Good Aesthetics

Diastema can be produced (not connected to adjacent teeth).

Enables use of overdenture prosthesis.

Can be used during orthodontic treatment for anchorage

Long-term survival however is good Lindhe et al 1998 in his meta-analysis

suggesting greater than 90%. Tan et al in 2004 showed 89%.Pjetursson et al in

2012 showed it is 89%

The classification of implants may be based on:

Position of placement (subperiosteal, transosseous, endosseous)

Material of construction (titanium, ceramic, carbon, alloys)

Design (screw, cylinder)

5.Autotransplantation

Success rates can be over 90% if transplanted into extraction socket

As low as 60% in artificially-formed sockets ( when tooth fully- developed)


Techniques to increase the amount of bone at area of hypodontia for

implant insertion

1) Autogenous bone graft

From oral sites

Symphysis,

Retromlar area,

Maxillary tuberosity,

Zygoma

Other areas for harvesting


Iliac crest

Tibia;

2) Allogenic bone graft: theoretical concern over possibility of disease

transmission using substitutes.

3) Osteodistraction and crestal widening.

Advantages and disadvantages of build-up small teeth before, during or

after orthodontic treatment (Kokich and Spear, 1997)

1. Before Orthodontics

Advantages

• Restoration acts as a space maintainer during treatment

Disadvantages

• Space may not be available before treatment for a build-up

• Altering the crown morphogy may result in incorrect bracket placement

• The restoration at risk of damage during bracket removal at completion of the

orthodontic treatment.

2. During Orthodontics

Advantages

• Excess space can be created temporarily to aid mesial and distal restorative

• Restoration acts as a space maintainer

Disadvantages

• Gingival inflammation can jeopardize bonding and ideal finishing.

• If composite is added to the labial surface of the tooth it may be necessary to

drop down archwire out tooth position.

3. After Orthodontics

Advantages

• Allows gingival inflammation to subside after appliance removal.


Disadvantages

• A new retainer may need to be after completion of restorative treatment

• More difficult to finish interproximally correctly.

Factors affect the choice of the prosthesis to restore the space

(Kokich and Spear, 1997)

1. Smile line

2. Gingival thickness

3. Height and width of bone at hypodontia site

4. Bone quality, volume and anatomy

5. Root position of the teeth adjacent to the implant site

6. Width, height and form of the adjacent teeth

7. Interocclusal space

8. Presence of parafunctional activity and occlusal forces

9. pt motivation;

10. social factors;

11. medical factors

12. no. teeth to be replaced;

13. patient and clinician preferences


Treatment option for missing lower premolars

De-coronation of the premolar to maintain the bone until implant

Transplant of the premolar or upper third molar.


hypodontia by almuzian

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