‫ حيدر‬.‫د‬
‫الزريجاوي‬
17/4/2014
CL. III Malocclusion
Definition
CL.III malocclusion can be defined according to:
 Angle's classification: the mesiobuccal cusps of the maxillary 1st molars
occluding at least 1/2 cusp distal the buccal grooves of the mandibular 1st
molars, and the canines relationship, it described as upper canine is either 1/2
cusp or complete posterior to lower canine.
 British standards classification: the lower incisors edges lie anterior to the
cingulum plateau of the upper incisors.
British classification
Angle's classification
A CL. III malocclusion is rare as compared to other type of malocclusions, with an
incidence of possibly less than 5 %. Individual CL. III cases are characterized as
having a retruded maxilla or a prognathic mandible and in some cases by a
combination of both. It is of special interest to the orthodontist because it offers a
therapeutic challenge.
In CL. III cases, the lower incisors and canines are inclined lingually because of the
pressure of the lower lip in its effort to close the mouth.
The disharmony between maxilla and mandible may be of lesser degree with a
normal occlusion on one side of the arches and a CL. III occlusion on the other, so it
is called CL. III subdivision.
-1-
Orthodontics……….…………………………..…............... Cl. III Malocclusion
Clinical Features
Extra-Oral Features
 A concave facial profile.
 Anteriorly divergent profile.
 Long face (increased lower face height), which may be
pointed at the chin.
 Mandible appears to be well developed (with an obtuse
gonial angle).
Intra-Oral Features
 A CL.III molar relationship.
 A CL.III canine relationship.
 A reverse overjet with possibly labially inclined
lower incisors and lingually inclined upper
incisions.
 A posterior cross-bite unilateral or bilateral (or
functional) due to a constricted maxillary arch or a
more forward positioned mandibular arch.
Classification
In evaluating the CL.III relationship, it is important to consider whether the problem
is dentoalveolar or skeletal in origin. In the diagnosis of CL.III malocclusions,
patients may present with CL.III symptoms such as multiple teeth in anterior
crossbite, minimal overjet, or lingually inclined lower incisors. In summary, anterior
crossbites may be caused by the improper inclination of the maxillary and mandibular
incisors (dentoalveolar), occlusal interferences (functional), or skeletal discrepancies
of the maxilla and/or the mandible.
-2-
Orthodontics……….…………………………..…............... Cl. III Malocclusion
Etiology
Skeletal factor
Skeletal relationship is the most important factor in the etiology of most CL.III
malocclusion, and the majority of CL.III incisor relationships are associated with an
underlying CL.III skeletal relationship. The growth pattern and the size of the jaws
are affected by heredity. Many studies showed that distinct characteristics of a CL.III
malocclusion due to prognathic mandible were related to genetic inheritance.
Soft tissue and habits
Functional factors and soft tissues have minor influences on the CL. III malocclusion
pattern. Macroglossia, or anteriorly tongue posture, which lies low in the oral cavity,
are to be a local factors in CL. III development. The excessive mandibular growth
could arise as a result of abnormal mandibular posture because constant distraction of
the mandibular condyle from the fossa may be a growth stimulus.
Dental factor
Occlusal forces created by the abnormal eruption may produce unfavorable incisal
guidance and promote a CL.III relationship. This may present initially as a pseudo
CL. III but if unattended can lead to a true skeletal CL.III dysplasia. Premature loss
of deciduous molars may also cause anterior mandibular displacement. If the
mandible loses it's posterior proprioceptive and functional support in habitual
occlusion it is often positioned anteriorly in an attempt to establish full occlusal
contact during chewing.
Congenital Abnormalities
A transverse as well as anteroposterior restriction of the mid-face growth can occur in
cases of cleft lip and palate with a normal mandible, markedly when the patient has
undergone the surgical repair. This can be attributed to restraining effect of scar
tissue following surgical intervention. Limitation in vertical growth of the maxilla
can also be seen.
Management
CL.III malocclusion can be classified as Dentoalveolar, Functional, or Skeletal,
which will determine the treatment approach and prognosis. It is known that Class III
malocclusion exacerbates during growth, mainly starting at adolescence.
The goals of early interceptive treatment of CL. III malocclusion may include the
following:
-3-
Orthodontics……….…………………………..…............... Cl. III Malocclusion
1. To improve skeletal discrepancies and provide a more favorable environment
for future growth.
2. To prevent progressive irreversible soft tissue or bony changes. Anterior
crossbite is often accompanied with Class III malocclusion can lead to thinning
of the labial alveolar plate and/or gingival recession.
3. To simplify phase II comprehensive treatment. In mild and moderate Class III
patients, early treatment may eliminate the necessity for orthognathic surgery
treatment.
4. To improve occlusal function, especially if it is accompanied by a functional
shift.
5. To provide more pleasing facial esthetics, thus improving the psychosocial
development of a child.
Treatment of Dentoalveolar & Functional CL.III Malocclusion
Early treatment should be considered in these cases, in order to avoid potential
adverse growth influences in the maxilla and mandible, and to improve upper lip
posture and facial appearance. Correction of multiple teeth in anterior crossbite has
been accomplished by using a fixed or removable appliance. During mixed dentition
stage, the removable appliance with springs can be used successfully to tip one or
more of upper incisors labially. In addition, a mandibular Hawley appliance with an
anterior labial bow can be used to tip the lower incisors lingually. Correction of CL.
III malocclusion by changing in the upper and/or lower incisors inclination can be
considered in cases with following features:
-4-
Orthodontics……….…………………………..…............... Cl. III Malocclusion
 A CL.I and mild CL.III skeletal pattern.
 The upper incisors are not already proclined and the lower not
already retroclined.
 Sufficient overbite should be present at the end of treatment, to
retain the corrected incisors position.
Treatment of Skeletal CL. III Malocclusion
Treatment of Growing Patients
The developing skeletal Class III malocclusion is one of the most challenging
problems confronting the orthodontists. Differentiate between midface deficient Class
III patients that would benefit from early treatment vs. a true mandibular
prognathism that may require surgical correction later. Class III malocclusions are
growth related problems that often become severe if left untreated, so the treatment
could be beneficial if initiated early.
Among the approaches for treating skeletal CL.III malocclusion is the growth
modification by using of orthopedic appliances, such as chin-cup, facial masks, and
functional appliances.
Chin Cup Therapy
CL.III malocclusion with a relatively normal maxilla and a
moderately protrusive mandible may be treated with the use of
chin-cup. Chin cup is used to apply forces (450 gm per side),
which are directed along the direction of growth of the condyle.
Therefore it's action are accomplished to lesser extent by
restraining the forward growth of the mandible, and to larger
extent by change in the direction of mandibular growth, rotating
the chin down and back. In addition, lingual tipping of the lower
incisors occurs as a result of the pressure of the appliance
on the lower lip and dentition. The lower anterior facial
height tends to increase so it is contraindicated for a child
who has excessive lower face height.
-5-
Orthodontics……….…………………………..…............... Cl. III Malocclusion
Functional Appliance Therapy
The Frankel III appliance is used in treatment of cases with mild maxillary
deficiency, and can be effective if the case is diagnosed early. The biggest problem is
of patient cooperation. The Frankel III appliance possible action is made with labial
(vestibular) pads to stretch the upper lip in addition to the periosteum forward, in a
way that stimulates forward growth of the maxilla. At the same time, it does not
allow the mandible to advance forward. Actually, most of the improvement is from
dental changes. The appliance allows the maxillary molars to erupt and move
mesially while holding the lower molars in place vertically and anteroposteriorly tips
the maxillary anterior teeth facially and retracts the mandibular anterior teeth.
Vertical movement of maxillary molar will help in rotating the chin down, back, and
improve facial appearance.
Facemask (Delaire Mask) Therapy
The facemask can be used in growing patients with Class III
malocclusions due to both anteroposterior and vertical
maxillary deficiency, to help provide the impetus for the
maxilla to grow anteriorly and/or rotate downwards. This
causes a reciprocal downward and backward rotation of the
mandible. It. is a very effective appliance if the patient is
cooperative.
The facemask obtains anchorage from the forehead and chin. The forward force on
the maxilla is generated via elastics that attach to an intra-oral maxillary appliance
(either fixed or removable). The removable appliance if used, it is preferred to be as
splint to make the upper arch a single unit for maxillary protraction. The maxillary
appliance must have hooks for attachment located in the canine-primary molar area
-6-
Orthodontics……….…………………………..…............... Cl. III Malocclusion
above the occlusal plane. Approximately 350-450 grams of force per side is applied
via the elastics for 12-14 hours per day.
Treatment of adolescent and non-growing patients
Treatment in the adolescent age is limited to Orthodontic Camouflage or
orthodontic decompensation in an effort to prepare the patient for surgery.
Camouflage can be achieved by proclining the maxillary incisors and tipping the
mandibular incisors lingually. Single arch extractions, 1st premolars extraction only in
the mandibular arch, are frequently done to create space for the retraction of the
mandibular anterior segment. CL.III elastics in combination with fixed appliance are
frequently used in an effort to tip/retract the mandibular incisors. In a more severe
cases and after the growth is ceased, Orthognathic Surgery is indicated. The most
commonly used surgical procedures are the bilateral sagittal split osteotomy with
retraction of the mandible in cases of mandibular prognathism, in cases of maxillary
deficiency a Le-Fort I down fracture may be attempted.
CL.III Elastic
Orthognathic surgery
-7-