Treatment of basal anomalies of the sagittal direction: Class 3
- CLASS III PREVENTION AND INTERCEPTION :
- Actions on the functional matrix :
- Avoid the prone position when sleeping
- Establishment of nasal ventilation as early as possible
- Ensure early nose-blowing habits and upper airway monitoring;
- Breastfeeding and non-mixed feeding from the onset of
temporary dentition.
- Establishment of eating behaviors requiring sufficient muscular activity.
- Correct the low and forward position of the tongue by:
- performing a lingual frenectomy;
- restoring nasal ventilation;
- freeing the oropharynx by tonsillectomy if necessary.
- Wearing a nighttime lingual shield (NLS) or splint
functional for class III.
- Suppression of parafunctions (onychophagia, digital sucking with traction on the mandible)
- Correction of a reverse incisor occlusion:
Dentally induced reverse incisor or end-to-end occlusions should be corrected as soon as possible to avoid locking of maxillary growth or mandibular prolapse.
Simple devices can be used:
- palatal plate with jacks or springs (vestibular, Schwartz);
- Removable mandibular appliance with vestibular arch for lingualizing the incisors;
- quadhelix with long internal arms that vestibulate the upper incisors;
- Correction of mandibular prolapse :
When mandibular prolapse is related to occlusal interferences, grinding of the temporary canine cusp tips, combined with maxillary transverse expansion, may be sufficient to restore occlusal stability and prevent prolapse.
- ORTHOPEDIC TREATMENT :
Orthopedic treatment aims to correct the skeletal discrepancy and restore normal occlusion by acting on growth through:
- to the stimulation of maxillary growth;
- and/or slowing of mandibular growth.
Orthopedic treatment is indicated during the growth period.
Therapeutic means :
- Delaire ‘s mask :
The Delaire mask is an orthopedic device that allows the application of heavy, intermittent forces in a posteroanterior direction.
Description :
The external device :
The mask is made of a forehead support connected to a chin strap by lateral metal rods. At the commissural line , a hoop is welded to allow the elastics to be attached. It can be adjusted in height and width.
Intraoral device : (Double Delaire arch )
It is made of two very rigid 10/10mm arches, welded onto two rings
molars. The palatal arch is adjusted to the neck of the teeth;
The vestibular arch must be placed at least 1 mm in front of the vestibular face
teeth to allow expansion of the premaxilla.
On the distal face of the lateral, a curved horizontal hook will be welded towards
the back which will allow you to hang the elastics.
Variations : Pull-ups can be performed on:
- a 4-ring circuit breaker;
- A sealed disjunction splint with a molar and premolar overbite plane.
The elastics :
The elastics will be loaded on each side to symmetrize the forces
These are heavy orthopedic forces, adapted to the child’s age. They are around 300 to 400 g for children around 6 years old and can reach 800 to 1,000 g, or even 1,500 g.
Pull-ups should always be oblique downward and forward.
Daily wearing time : The duration is approximately 14 hours per day. The port will be mainly at night
Processing time: it varies between 6 months and one year of treatment.
Effects of Delaire ‘s mask : Traction causes:
- at the skeletal level, an advancement and tilting of the maxilla around the frontomaxillary suture;
- Obstruction of mandibular growth. Delaire’s mask causes slight posterior rotation of the mandible.
- at the dentoalveolar level:
- mesialization of the maxillary arch with vestibulo-version of the incisors.
- a slight molar egression;
Indication : Class III due to maxillary retrognathism.
- The occipito-mental sling :
It involves applying forces to the chin to slow down the development
towards the front of it.
It consists of a chin strap connected to a helmet by elastic bands.
It can be applied very early in children, from 1 year old up to 4 or 5
years,
This device is worn only at night, for 6 months or even 1 year, never longer.
The sling prevents the mandible from moving forward and forces the child to close the mouth,
thus moving the tongue back.
Indication :
It should be used as soon as we see an inversion of the incisal articulation in a very young child.
Indicated in mild to moderate prognathism, the occipito-mental sling tends to slow mandibular growth.
Slingshots are little used today due to the joint stresses they place.
- ORTHODONTIC TREATMENT OF CLASS III
Orthodontic treatment is indicated:
- After the orthopedic treatment phase to correct dystopias and
perfect the occlusion
- In case of failure of orthopedic treatment
- In adults (without significant aesthetic damage).
Class III orthodontic treatment is most often carried out in permanent dentition and aims to re-establish a Class I occlusion.
- Treatment without extractions : Indicated:
- In the absence of DDM
- In the presence of moderate inter-arch discrepancy
- Normal or end-to-end incisal occlusion
The means :
Class III intermaxillary tractions :
They allow the distalization of the mandibular arch and the mesialization of
the maxillary arch.
Their vertical component causes egression of the maxillary molar which can lead to mandibular posterorotation.
- Treatment with extractions : Indicated in cases of:
- Significant bulk
- Reverse bite incisor
- Significant inter-arch offset
Extractions of 15- 25- 34- 44 : This is the preferred choice in classes III because:
The extraction of 34 and 44 allows the retraction of the mandibular incisors and canines, re-establishing the anterior guide and the correction of any crowding;
Extraction of 15 and 25 :
- facilitates the mesialization of the maxillary molar sectors restoring the molar class I;
- maintains the dental elements in the often hypoplastic anterior maxillary region, thus ensuring better support of the upper lip;
Extracts from 14-24-34-44 :
They respond more to the problem of anterior maxillary crowding, particularly in cases of included or dystopic canines.
They reduce the volume of the anterior part of the maxilla.
Single-jaw extractions of 34-44 : Indications:
- Class III occlusion with a normal maxillary arch
- mandibular crowding
- Incisal reverse bite;
This choice of extractions is very exceptional due to its often unfavorable occlusal consequences:
– occlusion of the second maxillary premolar with the first molar
mandibular requires occlusal equilibration by grinding,
- SURGICAL-ORTHODONTIC TREATMENT OF CLASS 3:
Indications for surgery : Surgery is indicated:
- In the event of a very significant discrepancy with significant aesthetic damage
- In cases of severe skeletal class III which has not been or could not be
reduced during growth;
- In adults for whom orthodontic treatment cannot ensure the reduction of alveolar misalignment
- In case of associated transverse or vertical bone anomaly;
It is performed after the end of growth in order to avoid any risk of postoperative recurrence linked to late mandibular growth , especially in boys.
Different types of surgeries :
It affects the maxilla, the mandible or both:
Maxillary surgery :
It is a maxillary advancement surgery of the Lefort I type, modified Lefort I, Lefort
II. In major syndromes, Lefort III surgery can sometimes be performed.
Mandible surgery
It is most often a mandibular retraction surgery obtained by sagittal cleavage of the Dalpont-Obwegeiser type.
Mandibular surgery reduces chin projection but decreases facial depth and the space available for the tongue. It therefore exposes the patient to a risk of recurrence.
Treatment of basal anomalies of the sagittal direction: Class 3
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