Maxillo-Mandibular Impingement (MMI)

Lecture presented at the 38th CIRNO Congress and 8th Pedro Planas Spanish Association Meeting: "New Classification of Occlusal Supports. Articular Compromise and Neuro-Occlusal Rehabilitation (RNO)". Author: Larena-Avellaneda Mesa, José. Valencia, 8-10 October, 2000.

            Set of symptoms and signs mainly sensitives, headache (migraine or migraine headache) and vegetatives, instability (dizziness, vertigo) caused by impact or collision of the mandible against the maxilla during functional movements being reduced or limited.
In the masticatory system, temporomandibular joint is compromised; functional impairment refers to mastication and phonation: the cause of MMI is extra or intraarticular and may be unilateral or bilateral.

Etiological classification. 
I. Dynamic.
A.-Maxillo-Mandibular Impingement, MMI:
-1. Extraarticular:
a. At the zygomatic orifice:
-In the opening:
   - By unilateral or bilateral coronoid process hyperplasia.
   - Zygomatic orifice decrease.
   - Jacob’s disease.
-b. In the maxilla:
    -In the opening.
    -In the subluxation.
    -In the lateralities.
    -In the protrusive.
    -In the closure.
      - All possibilities according to the structures that impact with them.
      - By increasing vertical dimension at the maximal intercuspidation (double occlusion, etc.).
-c. By oppression of the lingual nerve: Burning Mouth Syndrome. (BMS)
-2. Intraarticular:
-a. In an unilateral TMJ subluxation. Pathogenesis of the TMJ subluxation: unilateral mastication and functional and occlusal imbalance. In both cases the TMJ that suffers the most is the usual chewing side.
B.- Temporal Muscle Syndrome (TMS): at the zygomatic orifice:
    -1. Extraarticular:
-a. At the opening:
          - By unilateral or bilateral coronoid process hyperplasia.
          - Decrease of the zygomatic orifice.        
-b. On one laterality or lateralities.
-c. On the protrusive
    -2. Intraarticular:
-a. In an unilateral TMJ subluxation. Pathogenesis of the TMJ subluxation: unilateral mastication and functional and occlusal imbalance. In both cases the TMJ that suffers the most is the usual chewing side.
II. Static. Postural. Pressure habits: MMI, BMS and/or TMS.
A: Passive:
     -1. Lying on the sleeping or resting side (bed, sofa tv, reading, etc.): Pillowing.
     -2. Sitting: head support with one hand (studying, computer, travel seat, etc.)
B: Active:
     -1. To perform any kind of physical activity required by the protrusion: sport, 
           phonation, etc.
     -2. To perform any kind of physical activity that involves keeping neck bending:
           use of computers, reading, sewing, etc,.
MMI can also be presented in simultaneous combination to perform different movements, for example at closure and lateralities, etc.

MMI most frequent example, in the 2nd situation.
Skull with MMI produced by the upper left chordal, +8, extruded, vestibule displaced, upon impact with the inner side of the mandibular ramus in the mastication movement on the right side.

1.   Extruded chordal,+8.

2   Vestibule displaced chordal, +8

3   Mandibular lateral movement to the right, movement like chewing on the right side. The arrow indicates the compromised area, left side, where the vestibular edge +8 impacts with the inner surface of the mandible ramus.

4  Seen from caudal view,mandibular laterality movement the right.The arrow indicates the compromised area, left side.

MMI at zygomatic orifice level. Observations.
MMI pathology has been previously described only at zygomatic orifice level by the following authors: Langenbeck, 1853, coronoid process hyperplasia.

5  Julio Villanueva, Hospital Clínico San Borga Arriarán, Chile.

Farabeuf, 1.866, (Testut), being variable the distance between coronoid  process and the malar backside at the zygomatic orifice, if anteroposterior orifice length decreases or/and apophysis is more developed than usual, just an exaggerated propulsion movement is enough to establish contact between anterior coronoid edge and the malar.

6  A: normal distance. B: decreased distance.

Nelaton (Testut) describes the TMJ luxations, such contact is very common
           depending on the coronoid process type.
 7  Jacob, 1886, talks about hyperplasia and/or coronoid process osteochondroma with
    pseudoarticulation between coronoid process and malar.

8  CT. scan showing coronoid process impingement in the inner surface of the zygoma with bone remodeling.

According to radiographic findings, hyperplasia of the coronoid process was detected. Ana Capote, Hospital Universitario de la Princesa,Madrid..

9      Zygomatic orifice and normal distance between coronoid process and malar.

10  Mandibular condyle  in glenoid fossa

11  Mandibular condyle, “dislocated” and impact of the coronoid process
       against the malar, seen from caudal view.

12  “Dislocated” mandibular condyle and coronoid process impact against  malar,
      seen through zygomatic orifice.


1.- MMI at zygomatic orifice opening level by bilateral coronoid process      
 Case 1.
 14 years old teenager. Limited opening to 16 mm. Doesn’t show any pain, just discomfort because can not chew due to laterality limited movements. Overbite. Since childhood has difficulty opening the mouth properly.

13   The orthopantomography is from 2004, with 10 years old, which already shows                    
 a coronoid process hypertrophy.



                                                    16                                                    17
                                              18                                                      19
TVD study: lateral, oronals y parasagital
 Patient has limited mouth opening. Doesn’t show any pain.  

MMI in the maxilla. Observations.
Firstly is to ensure that TMJs palpations are not painful (CMD differential diagnosis).
At inspection we can observe the space existing between mandibular ramus inner side and maxilla at maximal intercuspidation and when making laterality movements, protrusive and the maximum opening, paying special attention if there is subluxation.
Next, will perform a palpation on the mandibular ascending ramus inner side. If MMI does exist, palpation is very painful.

 20 (11.1) MMI is directly related to the usual mastication side and sleeping side, so it usually chews on the same side, it will be the side that hurts the most and occurs that like it hurts more on the sleeping side, the patient tends to chew on the other side, and it gets worse because is also making MMI by laterality on the slleping side.

For MMI diagnosing in the 2nd situation, on the lateralities, will ask the patient to do it and will observe if there is space between mandibular inner side and antagonistic maxilla either tooth, prosthesis, etc. To verify diagnosis we ask the patient to chew only on the pain side and sleep by the non-painful side. Within a few days MMI pain will disappear and a lot of the accompanying symptomatology, ensuring MMI diagnosis.
MMI diagnosis in the 3rd situation will come after observing if the patient has the habit of doing mandibular protrusive movements, physical exercises for long period of hours with flexed neck and, of course, when mandibular hypertrophy cases are suspected. If we find a possible relationship between physical activity and the appearance of symptoms, we have to tell the patient to refrain from such activity for a few days and check if symptoms repeat or not.
MMI diagnosis and testing in the 4th situationat closing, is very simple:
-a: we can see if impacts against any tooth, prosthesis or alveolar process the 
mandibular antagonist mucosa or maxillary.
-b: double occlusion has increased its normal vertical dimension.
Another litmus test for MMI diagnosis is the placement of some anesthesia in the maxillary area where mandible impacts, as long as the patient is in pain at examination time. Pain will disappear within seconds.

MMI elimination cause by:
-       extraction.
-       Tooth carving or prosthesis.
-       Tuberosity surgical removal of the maxilla alveolar process.
-       Control or prohibition of physical activities that involve neck flexion with mandibular protrusion for hours, such as needlework( sewing, jigsaw, electric machines, etc.) use of computers, extended reading without the use of lectern, etc.; in general any tensed physical exercise maintained overtime with flexed neck body posture which requires mandibular protrusion.

The following clinical histories are summarized and we highlight only the most important data.
We have only presented a selection of different cases in the characteristics of their pathogenesis and treatments.

Case 1.
Patient: P.C.H. Age : 59 years old. Starting date: 30/04/98
Begins 6 years ago with a pain in the right ear and temple. He says having problems in the right ear for over 15 years. He started having noises in the right ear a year ago”as if hearing the sea”. The right eye is half closed when the pain appears. Eczema in the right ear hole and itching. When pain occurs, can not articulate words very well and feels like his mouth twists to the left side. Right TMJ noises when chewing. Pain radiates to the temple, jaw, eye, neck, back and right arm.
Presentation mode: Little by little and increasing.
Location: right ear. Pain at palpation on the right vertical mandibular ramus inner side.
Irradiation: temple, eye, neck, back and right arm.
Length: days, up to a week.
Frequency:  twice per week.
Intensity: 7, 8 ( on a scale of 0 to 10)
Quality: Beats.
Time pattern: There isn’t any, at night neither.
Accompanying symptoms: right eye is half closed, does not articulate well the words and twists his mouth. Triggering factors: no.
Another symptoms: eczema, itching, noises in the right ear.
Previous treatments: pain infiltrations on neck and back.
Splint holder: no. Gum chewer: no.


MMI when chewing on the left side impacting the right ascending ramus mandible inner side against the upper right alveolar process. Must chew on the right side and sleep on the left one to confirm diagnosis.
Elimination of MMI cause, right alveolar process.

Case 2.
Patient: V.F.C. Age: 34 years old. Starting date: 15/03/07. Reason for consultation: pain on the right side of the head. Background: implants placement a year ago.
Mandible pain area for a year., in front of the ears, neck, teeth, the whole right side. Discomfort when talking, chewing. Worse in the morning upon awakening. It says he chews on his right side, but used to do it on the left side. Does not relate it to mastication. Feels a crack in the right TMJ.
Dizziness with pain and nausea feeling.
Bothers when talking, its related to this. Speaks very low for not moving the mouth. Mumbles.
15/03/07. Carved by distovestibular crown implant +7 to eliminate the MMI.



          24   Centric occlusion

25  Left laterality movement, usual chewing side, and MMI situation on the right side when impacting mandibular ramus inner side against last molar.

26   Distovestibularl carved last molar to eliminate MMI.

27   Checking the space between mandible and last molar: eliminating MMI.

28   Left laterality movement to check that MMI does not exist.
Case 3.
Patient: S.H.C. Age: 75 years old. Starting date: 12/07/02
Since three years ago, pain in front, inside and behind ears, temples, eyes, head, radiating to the face, neck, nape, shoulders, arms, hands,...
Limited mouth opening feeling
Pain at palpation on the left vertical mandibular ramus inner side.
Left MMI. Chews on the right side and sleeps on the left side.
Posterior cut of the upper prosthesis left side. Decrease of PMFA (Planas masticatory functional angle). Must chew only on the left side and sleep on the right side.
29 (3.1) In centrics and normal vertical dimensions.
30 (3.2) Right laterality: MMI caused by the upper prosthesis back side.
31 (3.3)Upper prosthesis: compromised.
32 (3.4) Posterior side causing MMI has been eliminated.

Case 4.
Patient: S.J.R. Age: 31 years old. Starting date: 25/10/02
Discomfort on the left TMJ two months ago and pain has intensified this last week.
Pain at palpation on the left mandibular ascending ramus inner side.
Left MMI, because it’s on the right side where he usually chews. +8, is vestibular displaced.
+8, extraction.
33 (4.1) +8, vestibular displaced position.
34 (4.2)  Left MMI by chewing on the right side.

Case 5.
Patient: C.H.G. Age:  44 years old. Starting date: 24/09/03
During 18 years and after putting on a partial prosthesis, suffers from nausea, vomits, dizziness, unsteadiness, loss of balance.
Pain in the neck and right arm. Congested feeling on the right side of the head. They explore her and loses her balance and falls to the right side when standing on her feet with closed eyes.
Pain and noises in the ears, stronger in the right ear, throbbing in the eyes, double vision, head pressure, hearing loss...
Different treatments for Meniere’s syndrome diagnosis, anxiety, anguish...
February 2003, extractions and full prosthesis. All symptoms get worse, progressive loss of the voice.
June 2003, contact with us through the website and advise her to remove prosthesis to observe if symptomatology disappears, assuming a possible bilateral MMI but more emphasized on the right side. Should also sleep on the left side. Some symptoms disappear and others decrease in intesity. Continues with loss of balance when closing the eyes.
Pain on the right side, ear, temple, neck, right arm; double vision, dizziness. No distress, uncongested face, voice recovery, no nausea or vomits.
We do a test to confirm MMI by the prosthesis, asking her to put them on: general worsening. Again, without prosthesis: MMI confirmed.
Pain is better located now in the inner side of the mandibular ascending ramus right side and from there it radiates to the ear, etc.
September 2003, explored at consultation and there is bilateral MMI pain due to the prosthesis and without prosthesis there is MMI pain caused by upper right alveolar process.
Prosthesis bilateral MMI and right unilateral without prosthesis by upper right alveolar process.
Upper alveolar process bilateral osteotomy.
25/09/03.  It is a little better.
27/09/03. Feels much better and without pain on the right side. Loss of balance  continues.
29/09/03. She shows me that no longer falls and that doesn’t lose balance when closing her eyes, after 18 years. She is very excited.
31/09/03.  Remove sutures of the wounds and proceed to prosthesis repair.

35 (10.1)  Entire prosthesis at functional occlusion.

 36 (10.2)  Right laterality movements, MMI caused by prosthesis.

37 (10.3) left laterality movements, MMI caused by prosthesis.

38 (10.4)  Observe upper alveolar process morphology and proximity to the mandibular ascending ramus

39 (10.5)  MMI when moving mandible to the right side.

40 (10.6 ) MMI when moving mandible to the left side.

41 (10.7)  Osteotomy the following day. (SEE VIDEO DR. ANDRÉS GARCÍA)

42 (10.8)  Seven days later. Sutures removed.

43 (10.9)

44 (10.10)  Notice difference in size between alveolar process before and after osteotomy. Lines indicate alveolar process removed areas towards vestibular  avoiding MMI when prosthesis are placed back again.

 45 (10.11)  Upper prosthesis repair.

 46 (10.12)  Prosthesis at functional centric.

47 (10.13)  Right laterality movement. No MMI.

 48 (10.14)  Left laterality movement. No MMI.

Case 1.
Patient: W.S.H. Date of birth:  01/08/2001. Age: 5 years old. Starting date: 14/03/2007. Consultation reason:  Pain 4 days ago.
The child says that when he was playing at break time a pain began on the upper left last molar and after that it radiated to the other last four molars.
He was doing physical effort .The mother says that lately sees him with forward mandible.
Location: on palpation, distal of the V molars
Presentation mode: Not cooling or warmth sensation
Other symptoms:  Has the habit of doing protrusive movements.
Treatment: ¿¿¿???
49 Protrusive posture

50 Protrusive posture

51 Centric occlusion

52 Protrusive position

53 Upper arcade. MMI caused by impacting mandibular mucosa against maxillary mucosa in the eruption area 6+6.

 54 Lower arcade. MMI caused when mandibular mucosa impacts where 6-6 will erupt against last upper temporal molars.

Case 2.
Patient: L.P.C. Age: 6 years old. Starting date: 24/05/07 Consultation reason: right ear pain. Background:  Thumb-sucker.
Begins with right ear pain a month and a half ago and has fever so they take her to to the ENT specialist and, like she swims in the pool, she was diagnosed with otitis even though she wears earplugs. Treatment: Augmentine + Naso cort nasal spray for 10 days. Also, mother tells, that the girl wakes up with sore neck, more on the right side as if she had torticollis.
Like she was exactly the same, went back to the ENT specialist told her to wait another 10 days and keep the same treatment + antihistaminic. She continued the same.When the mother put on the earplug in the right ear to give her a bath, it was hurting. The girl told her mother that her teeth were aching, so she came to the dentist. She hasn’t been at the pool for a month thinking it was an otitis according to the ENT specialist.
Does thumb sucking increase the pain and that is the reason why she wakes up with neck pain?
Treatment: ???
55  Protrusive posture

56  Protrusive posture

 57 Erupted teeth 16, 26

 58 + 36 and +46 teeth haven’t erupted and we observe at the mucous the cusps impact prints of teeth +16 and + 36 when closing and protruding.

59 Normal centric occlusion.

 60 Starting postion of the mandibular protrusive movement that causes MMI in protrusive.

 61  MMI protrusive position.

Case 1.
Patient:  S.M.G. Age:  50 years old.. Starting date: 22/12/05
Five years ago started feeling cramps in the right side of the face, maxilla and mandible. When she eats, smiles, gesticulates or talks, feels awhiplash. Sometimes whiplash reaches the ear. Feels the heat in all that area and skin becomes less sensitive. Right wing nose and the upper lip right side are trembling. Her lips can not get wet with the tongue.
It feels the right side of her face swollen. She had vertigos for almost a year.
Feels her canine upper right tooth, + 13,  more sensitive and believes that the pain comes from there.
It bothers her when brushing teeth and triggers the whiplash.
She foresees when is going to have a whiplash.
Weird sensation inside the mouth, tongue and palate.
Diagnosed and treated of trigeminal neuralgia. Last strong crisis in September 2005. Treatment with Tegretol, etc. It relieved the symptoms.
Cries a lot, feels helpless and doesn’t have quality of life.
Can not even talk because one small mandibular movement triggers the pain.
No pain on TMJs palpation.
We see when closing teeth in centric the mandible impacts against the upper right molar occlusal surface of tooth + 17. It also impacts the mandibular ascending ramus inner side against the upper alveolar process by distal tooth + 17.
Pain on palpation in centric mandibular compromised area.
Right MMI in centric.
Checking diagnosis:
Anesthesia and + 17 occlusal surface carving especially palatal cusps plus distal. We suggest patient to confirm diagnosis by eating only soft things on the right side without protrusive movements or mandibular lateralities.
23/12/05. Extraction tooth + 17.
03/02/06. Alveolar process osteotomy by Dr. A.García.

 62 (11.2) Mouth closed in centric position, relation and occlusion, and check how mandible impacts against  the occlusal surface of tooth +17. This explains us  why she doesn’t dare to do the slightest mandible movement  due to the pain caused when impacting against the + 17, even swallowing, talking, etc. and not to talk about laterality movements when trying to chew something  with anterior teeth.

63 (11.3) Patient’s ortopantomography. Click to enlarge

 64 (11.4) We carve occlusal surface of  + 17 to eliminate mandible impact in centric and at least can swallow and close the mouth without pain to verify this way MMI diagnosis.

65 (11.5) Checking mandibular impact elimination when closing the mouth.

66 (11.6)  Extraction tooth + 17.

 67 (11.7) We observe how mandibular ascending ramus inner surface impacts against hypertrophied alveolar process in centric.

 68 (11.8Alveolar process partial osteotomy to eliminate MMI.

 69 (11.9 ) In their closing movements...

 70 (11.10) ... and left laterality.

Case 2
Patient:  C.G.H. Age:  61 years old.. Starting date: 21/11/01
Pain every day for five years on the left mandibular ramus and radiating towards TMJ, ear, neck, shoulder and left arm. Wakes up with the feeling of having left TMJ “stuck”.
It’s got some noises when chewing on the left TMJ. Sometimes feels tense mandible.
Buzzing in the left ear. When left ear gets wet it feels more plugged and has got discomfort.
Teeth have been removed and now, 8 months ago, carries a full upper prosthesis and has missing teeth in the lower arcade. Removes prosthesis when sleeping.
Full upper prosthesis.
Lower arcade with missing premolars and molars on the left side; teeth + 17- and + 18 8 are missing on the right side.
Normal functional centric occlusion, correct vertical dimension.
The right PMFA(Planas Masticatory Functional Angle) is lower than the left one.
Pain on palpation in the left mandibular vertical ramus inner side.
Without upper prosthesis we can observe CAT in centric relation when tripping over the left mandibular vertical ramus inner side with the upper left alveolar process. Emphasized MMI when moving mandible to the right side. It would correspond to mastication movement by the right side.
Right MMI external cause when closing in centric relation without  prosthesis and when performing mastication movements on the right side.
We propose to the patient in order to confirm diagnosis, not to remove prosthesis even when he goes to sleep and only use left side when chewing.
1      Left PMFA decrease, so he can use this side for eating.
2  Upper left alveolar process elimination that compromises the joint and replacement of missing teeth...
71 (2.1) Open mouth without prosthesis.  72 (2.2) MMI when closing without prosthesis.
73 (2.3) Centrics and normal vertical dimensions.
74 (2.4) Right laterality: MMI                                                    75 (2.5) Left laterality.

76 (2.6) Left laterality:  PMFA decreased to facilitate only chewing on this side and confirm diagnosis.

Case 3.
Patient: R.S.L. Age: 36 years old. Starting date: 03/03/06
When he was 7 years old suffered a fall and it broke the mandible on the right side. Remembers the bandage and eating with straw. Since then when is going to sleep he interposes the right hand fingers between the dental arcades to keep the mouth from closing. Wakes up with generalized discomfort on teeth and gums, feeling relief when tightening the teeth.Lacerating pain every day, in temples, more on the right side, with palpitations, as if it had high intensity fire for a short period of time. Gets worse throughout the day and especially after meals.
In the year 2000 spent a month with dizziness and vertigo. 3 years ago noticed a lack of strength in hands and arms, especially on the right side.
Pain on palpation on the right mandibular ramus inner surface. Chews on the left side.
CAT on the right side.
28/03/06.  Plaques have been placed to avoid MMI on the right side.
30/03/06.  Slept well, without fingers in the mouth and hasn’t had headache.
28/04/06.  Extraction of + 16, 17, 18 teeth and osteotomy of the upper right alveolar process.( Dr. A. García.)
03/05/06.  Continues with no pain. Can chew much better.


78. Due to mandibular fracture  occlusion was altered  staying without  occlusal support in the right side, so when is closing  it impacts the right mandible ascending ramus  inner side against  occlusal surface of # 17 and  #18  causing  MMI when closing.

79  Occlusal interferences occur also in the mandibular closing trajectory altering centric relation.

80 Maximum intercuspidation occlusion.


Removal of the 3 right upper molars and  upper alveolar process osteotomy.

Case 4.
Patient:  M.F.R. Age  35 years old
Starting date: 01/01/08
Diagnosed with migraine headaches for over 10 years, bilateral, but more on the right side, nausea, dizziness, buzzing in the ears.
It wore splint for 3 years.
Right TMJ subluxation.
Pain in the impact zone due to maxilla closure right side.
MMI when closing.





Extraction tooth +7.

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