IDIO P A TH IC CON D YL AR RE SO RP TIO N A N D IT S IM P A CT O N

ORT HO D ON TIC T REA TM EN T

2016

MOH AM MED ALMU ZI AN

Introduction

Idiopathic condylar resorption (ICR), also known as condylar lysis and condylar

atrophy is a condition affecting the size and morphology of the mandibular condyles

(Papadaki, Tayebaty et al. 2007).

It affects females almost exclusively between ages 15-35 yrs with a peak around the

pubertal growth spurt (Huang, Pogrel et al. 1997), and because of this it has also been termed

“cheerleader’s syndrome”.

Condylar resorption was first reported by Burke in 1961(Burke 1961) who described

it as an “acquired condylar hypoplasia” and has since been recognised as a unique clinical

entity in 1977 (Rabey 1977).

Incidence

Adult condylar resorption appears to be rare. There is no current evidence to state that

the prevalence of condylar resorption and diminished mandibular growth in children exceeds

the rare incidence in adults.

Arnett and Tamborello 1990: Reported 10 cases of progressive Class II malocclusion,

secondary to condylar resorption in approximately 800 dentofacial deformities examined over

a 10 year period.

Remodeling of the TMJ

Functional and Dysfunctional Remodeling are two types of TMJ remodeling, they represent a

spectrum of articular surface changes with condylysis being the most severe, resulting in near

or total loss of the condyle.

Functional Remodeling (FR): This is characterized by morphological changes involving the

articular structures of the joint that are not associated with any significant alterations in the

mechanical function of the joint or occlusion. FR is identified by:

TMJ morphologic change

Stable ramus height

Stable occlusion

Normal growth

Dysfunctional Remodeling (DR) / Condylar Resorption: This is characterized by remodeling

which adversely affects the mechanical function of the joint and occlusion. It is associated

with excessive or sustained physical stress to the articular structures, which exceeds normal

adaptive capacity or exceeds a decreased adaptive capacity. DR is distinguished by:

TMJ morphologic change (decreased condylar head volume)

Decreased ramus height

Progressive mandibular retrusion (adult)

Decreased growth rate (juvenile)

DR (Condylar Resorption) causes the mandible to become progressively retrusive in

adults

Aetiologic theories

The cause and pathogenesis of ICR remains unclear (Papadaki, Tayebaty et al. 2007)

and in the majority of cases there is no clear identifiable cause.

Due to the strong predilection for females it is widely believed that a hormonal cause

is likely.

Two main theories have been

hypothesised by various groups:

A. The Arnett group (Arnett, Milam et

al. 1996) proposed a link with increased

loading of the TMJ and subsequent

pressure resorption, which may occur after

orthodontic treatment, orthognathic

surgery, parafunction or trauma (Arnett, Milam et al. 1996). Chong and colleagues (Chuong

and Piper 1993, Chuong, Piper et al. 1995) suggest that the condition is similar to that of

avascular necrosis of the femoral head (Perthe’s disease) which is characterised by damage to

vascular structures within the bone resulting in ischemia and osteonecrosis of the femoral

head.

B. More recently they investigated the association

between low estrogen levels (17beta-estrogen) and

ICR (Gunson, Arnett et al. 2009) and found strong

evidence for this as a major etiologic factor. It has also

been shown that components of the TMJ contain

receptors for estrogen in varying degrees which makes the hypothesis plausible (Abubaker,

Raslan et al. 1993). Investigations by Wolford, who has written extensively on ICR, is largely

consistent with the Arnett groups findings. He describes the pathophysiology cascade of ICR

(Wolford and Cardenas 1999):

Risk factors (Wolford and Cardenas 1999), (Arnett 2013)

1. Age and gender:

o Female – affects F>M (9:1)

o 15-35 years of age – associated with peak growth and hormonal activity

2. Local and systemic disease such as osteoarthritis and rheumatoid arthritis

Autoimmune disorders

Endocrine disorders

Nutritional disorders (Anorexia nervosa)

Metabolic diseases

Infectious diseases

Cardiovascular diseases

Blood dispraises

Excessive psychological stress

3. Occlusal factors:

o High MP angle – increased load on mandibular condyle, rarely develops in low angle

cases

o High OP angle – increased load on mandibular condyle

o Posteriorly inclined condyle

o High angle sk class II malocclusions - rarely develops in sk class IIIs

4. Hormones

o Low endogenous estrogen levels (17beta-estradiol) (Gunson, Arnett et al. 2009) -

High levels of exogenous Ethinyl Estradiol (EE) and Progestin – both found in oral

contraceptives cause a negative feedback loop to reduce levels of naturally occurring 17beta-

estradiol. This is thought to modify the adaptive process of the condyle to abnormal loading.

17beta-estradiol is osteoprotective as it inhibits osteoclastic activity and thus reduced levels

can predispose to bone resorption.

o Prolactin – “It is likely that prolactin contributes to the accelerated condylysis”

o Corticosteriods – Association with joint resorption (Hypothetical at this stage)

5. Mechanical factors:

o Articular disk displacement

o Parafunction

o Macrotrauma

o Unstable occlusion

o Increased condylar loading

o Pre-treatment condylar atrophy

6. Orthodontics

o Kato and colleagues(Kato, Hiyama et al. 1999) reported that orthodontic treatment

alone can cause condylar resorption after treating a 12 yr old girl with impacted canines.

Whether the condylar resorption was caused by the orthodontic treatment is unclear.

7. Orthognathic surgery, magnitude and direction of BSSO advancement

o Upward and forward rotation during BSSO is associated with high risk.

o BSSO advancement and Maxillary osteotomies will cause a sudden repositioning of

the condyle in the fossa, which increases the mechanical load in the joint (Arnett, Milam et

al. 1996).

o In most patients, adaptation to this change occurs, but in some the remodelling

capacity of their TMJs is impaired and their condyles will resorb.

o Arnett et al showed that over-seating the condyle in the fossa during BSSO can cause

compression and result in dysfunctional remodelling of the joint (Arnett, Milam et al. 1996).

o Patient who had a surgery with IMF have a higher risk

Diagnosis

Based on history, clinical examination and imaging.

1. History

Progressive worsening of occlusion and aesthetics

development of AOB.

If resorption is asymmetric, then Md deviation and class II relationship will occur on

the more affected side.

TMJ pain can be a feature during the active phase but not always (25% of patients

may have no pain (Wolford and Goncalves 2015)).

Presence of the above risk factors may also be present in the patient’s history.

2. Clinical examination

Patients will usually have

normal range of mouth opening when

the condition is in quiescence.

However speech and chewing

function is often affected,

occasionally breathing due to

soft tissue collapse into the airway

(Posnick 2013).

3. Imaging

Common lateral cephalometric radiographic findings include the following (Wolford and

Cardenas 1999):

1. Skeletal and occlusal Class II relationship

2. Anterior open bite

3. High mandibular occlusal plane angle

4. High mandibular plane angle

5. Decreased vertical height of the ramus

6. The lower incisors may appear overangulated

7. A significant decrease in the oropharyngeal airway can occur in the more severe

cases.

8. Intra-capsular

Common lateral cephalometric findings in a bilateral TMJ ICR include:

Skeletal and occlusal Class II deformity

Anterior open bite

High mandibular occlusal plane angle

High mandibular plane angle

Decreased vertical height of ramus

Lower incisors may appear over-angulated

Significant decrease in the oropharyngeal airway (in severe cases)

Findings in a unilateral case:

Unilateral skeletal and occlusal Class II deformity

Vertical height difference at the mandibular inferior border/ramus/OP

Open bite on the contralateral side

A P-A cephalogram may show worsening asymmetry

Method of imaging

I. MRI (Wolford, 2015): MRI findings include:

Decreased condylar volume

Anterior disc displacement with or without reduction on opening

Extreme thinness or loss of continuity of cortical bone on the condyle head

Thick amorphous soft tissue occupying the space between the condyle and fossa

II. Serial lateral cephalograms will demonstrate slow but progressive retrusion of the

mandible during the active phase.

III. The OPG can be used for gross examination of the condyle and will appear to have

lost mass relative to the rest of the mandible and it can appear thin or shortened with

flattening of the superior or anterior curvature(Hoppenreijs, Stoelinga et al. 1999). In many

cases, there will be a distal inclination of the condylar neck(Hoppenreijs, Freihofer et al.

1998).

IV. The value of radioisotope examination as part of the diagnosis of ICR is disputed.

This type of scan (usually done with technicium-99) is difficult to interpret because various

types of TMJ conditions will show a high level of uptake, however others feel it has some

diagnostic value(Huang, Pogrel et al. 1997).

Management

There are two important aspects when planning the correction of the existing

dentofacial deformity: (1) ensuring that the resorption process is inactive and (2) treating the

deformity in such a way that the loads on the condyles are not increased.

Treatment of ICR is controversial.

Orthognathic surgery has been attempted to manage

ICR, but the relapse rate is high, especially if the process is active at the time of

treatment or if it becomes reactivated during the postoperative period. Treatment modalities

currently used:

1. Conservative treatment (Van Damme and Merkx 1994, Huang, Pogrel et al. 1997,

Hoppenreijs, Stoelinga et al. 1999)

Ideally post-active phase

“Compensation” using splints, orthodontic tx with and without exo, restorative tx.

Any orthodontic treatment, such as Class III elastics, that increases the loading of the

condyles (and could reinitiate the condylar resorption process) should be avoided.

Shown to be stable

Occlusal splints should be used when there is pain and dysfunction in the TMJ and

also for a period prior to surgical correction (Arnett and Gunson).

2. Mx osteotomy only – to reduce risk of reactivation by avoiding condylar

trauma/overloading(Arnett GW 1990)

Ideally post-active phase

Does not always provide good aesthetic result (Hoppenreijs, Stoelinga et al. 1999)

(Tominaga, 2016)

Reactivation less likely

3. BSSO +/- Mx osteotomy

Ideally post-active phase

Many authors report high rates of relapse (Van Damme and Merkx 1994, Huang,

Pogrel et al. 1997, Hoppenreijs, Stoelinga et al. 1999). Even inactive condylar resorption can

be reactivated by BSSO and Le Fort I osteotomy(Hoppenreijs, Freihofer et al. 1998).

BSSO will increase the active mandibular length and thus increase the load on the

condyle.

All studies show that surgery of mandibular advancement causes a lateral, torque and

backward movement of the condyles, all harmful to the condyles. What are the possible

solutions to avoid failures? Patient preparation before surgery and surgery simulation with an

articulator, condylar position control during surgery, working with surgeons to achieve a

condylar portion stabilization system (with the CAD), quickly set up a mobilization of the

mandible by physiotherapy

A systematic review showed that there was a substantial consistency among studies,

however, that young, female patients with mandibular deficiency and high mandibular plane

angle, submitted to surgical counterclockwise rotation of mandibular segments, were more

prone to a higher risk for condylar resorption after BSSO (Mousoulea, 2016)

4. A segmental Le Fort I bilateral osteotomy, ramus increasing length inverted L-

osteotomy, and genioplasty combined with orthodontic treatment

5. Articular disk anchorage (mini-anchor) followed by BSSO

advancement(Wolford and Goncalves 2015)

Ideally post-active phase

BSSO advancement is stable

Normal TMJ function and ROM

6. Condylectomy followed by CCG (Wolford and Goncalves 2015) (costo-chondral

graft)

Condylectomy will cease active phase

CCG is ideal autologous material

Fixed rigidly

Slight posterior open-bite left to allow some vertical relapse

Aggressive physical therapy required

Good results

7. Condylectomy followed by alloplastic total joint prosthesis (Wolford and

Goncalves 2015)

Condylectomy will cease active phase

Should be used with fat grafts around prosthesis

Aggressive physical therapy required

As with any prosthetic joint, will need replacement after a number of years

Most stable

Considered superior to CCG

It seems that orthognathic surgery alone is not an ideal treatment for ICR. Reported long-term

results are not stable, and resorption may proceed or be triggered if quiescent preoperatively.

The role of the orthodontist before orthognathic surgery is to prepare upper and lower teeth to

an ideal arch form that will maximize occlusal contact in a normal Class I occlusion

postoperatively to minimize joint loading and potential for relapse.

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