Interceptive orthodontic treatment

Interceptive orthodontic procedure

Phase of the science and art of orthodontics employed to recognize and eliminate potential irregularities and malpositions in the developing dentofacial complex
A malocclusion, if detected as soon as possible, can be eliminated or made less severe, by initiation of interceptive orthodontic procedures
Ensure that an oral habit does not become fixed and its deleterious effects do not affect the normal growth and development of the patient
Ensure that there is no loss of arch length due to the premature loss of deciduous tooth / teeth or due to rotated teeth or on crowding of teeth and guide the growth of mandible by using myofunctional appliances so as to deliver greater benefits to the patient

Basic interceptive procedures

Space regaining
Correction of anterior and posterior cross bites
Elimination of oral habits
Muscle exercises
Removal of soft or hard tissue impediments in the pathway of eruption
Resolution of crowding
Interception of developing skeletal malocclusions

Space regaining

If not carried out on the premature loss of a deciduous second molar > permanent first molar may tip or move mesially > loss of the arch length > may impede the second premolar to erupt

Causes of mesial tipping / drifting of molars

Extensive carious lesions
Ectopic eruption
Premature extraction of primary molars without any space maintenance

Timing of distalization of 6 years molars

If the child is treated before the age of 9 years the root of the first permanent molar to be moved has not completed its growth and the orthodontic tipping or bodily movement to normalize its position is easier
However, the treatment is delayed too long and the second molar begins to erupt distal to the mesially drifted 6 years molar, the clinician has the problem of moving two molars distally, which requires greater force, therefore, requiring extraoral anchorage or corrective orthodontics
For most children, the age range between 7-10 years proves to be the best for tipping or bodily movement of 6 years molars distally, to recover lost arch space
The methods of space regaining are divided into two broad groups: Fixed appliances, Removable appliances.

Fixed appliances	Open coil space regainer (Herbst space regainer)	Band is adapted and pinched on the permanent first molar to distalize it Buccal and lingual tubes are soldered to the adapted band The tubes should be parallel to one another in all planes and their lumen should be aimed at the junction of crown and the gingiva of the first premolar A 0.7 mm stainless steel wire is then bent to a U shape, which will fit passively in both the buccal and lingual tubes The anterior part of the ‘U’ shaped wire should have a reverse bend where it contacts the distal outline of the first premolar The wire should contact the distal surface of the first premolar below its greatest convexity The coil spring is slipped on the wire The compressed spring will try to become passive and exert reciprocal pressure mesially to the premolar and distally to the permanent molar
	Jackscrew space regainer	To recover the loss of space caused by tooth drift into an edentulous area Uses 2 banded adjacent teeth and a threaded shaft with a screw and a locknut Activated regularly to exert a consistent force against the banded teeth The tube should be centered in the middle one-third of the band and aligned with the other banded abutment tooth Mesial end of the shaft is trimmed and contoured to the premolar band surface
	Gerber space regainer	May be fabricated directly in the mouth during one relatively short appointment and requires no laboratory work U shaped assembly is used into which the U shaped wire can be fitted
Removable space maintainer	Upper / lower Hawley’s appliance with helical spring	Can be used for both mandibular and maxillary molars Constant measurement of the child’s arch with the modified Boley gauge during treatment gives the dentist an exact indication of progress in moving the molar distally Usually it takes about 2-4 months to move a mandibular molar distally by a distance of 2 mm Placing the spring in an undercut also aids in retention of the appliance, whereas a spring not held in position tends to displace itself and the appliance
	Hawley’s appliance with split acrylic dumb-bell spring	Used to regain up to 2mm of lost space by tipping one of the permanent first molars distally Effective and comfortable appliance Dumb-bell spring allows easy adjustments to add distalizing force to the lower molar The limit of possible spring opening is at least 3mm which is beyond the necessity of the usual movement of this tooth The spring should be adjusted twice a month, creating an increment of opening in the split acrylic area of 0.5 mm at a time Any larger adjustments may not allow the appliance to be seated firmly into the area immediately mesial to the molar being moved distally
	Hawley’s appliance with slingshot elastic	Distalizing force is produced by the elastic stretched between the 2 hooks One hook is located on the middle one-third of the lingual aspect of the molar to be distalized and the other is arranged in the same position on the buccal aspect of the molar
	Hawley’s appliance with palatal spring	Made up of 0.5mm stainless steel wire Active arm of the palatal spring is placed mesial to the permanent molar to be distalized Activation is 2mm by opening of the spring Active arm should not be too long The helix diameter should be 2mm
	Hawley’s appliance with expansion screws	Types of expansion screws based on their incorporation Encased type : sturdy and resist stress Skeleton type : have a part of the spiral embedded in the acrylic and are therefore superior and generally more preferred now Rapid maxillary expansion

Correction of anterior and posterior cross bites

Cross bites should be corrected as soon as they are detected
May be better to treat them as the permanent teeth begin to erupt into the oral cavity. Child may be too young and uncooperative at the deciduous dentition stage. It is easier to bring about changes in the mixed dentition stage
Can be unilateral or bilateral, true or functional or combination
Could lead to skeletal malocclusion if not treated, which would require corrective orthodontic treatment later on
Common appliances used in correction of cross bites : tongue blade therapy, inclined planes, composite inclines, Hawley’s appliance with Z-spring, quad helix appliance, medium, mini and microscrews embedded in acrylic appliances

Elimination of oral habits leading to interception

Oral habits such as thumb / digit sucking, mouth breathing, tongue thrusting, lip sucking tend to cause malocclusions
All the oral habits lead to an imbalance in the forces acting on the teeth, causing the development of dental malocclusions and if left untreated over a longer period of time, these cause skeletal malocclusion
Oral habits also lead towards abnormal positioning of the tongue, aberrant lip and perioral musculature, development of unfavorable V shaped and high palatal arches

Muscles exercises

Muscle exercises allow a clinician to bring such aberrant muscular functions into normal functioning, to create normal health and function, aid in growth and development of normal occlusion
Uses : to guide occlusion development, allow optimal growth patterns, provide retention and stability in post-corrective

Exercises of orbicularis and circumoral group of muscles	Stretch upper lip in the posteroinferior direction by overlapping the lower lip to form an oral seal labilally Hold a piece of paper between the lips Swish water between the lips until they get tired Massage the lips Play a reed musical instrument Place a scotch tape over the lips helps to train them to remain sealed Use oral screen with holder Button pull exercise : patient is asked to place the button behind the lips and pull the thread while the lips try to resist the same Tug of war exercise : 2 buttons are used and another individual pulls the thread gently while the same movement is resisted, by the patient
Exercises of the tongue	One elastic swallow : orthodontic elastic placed on the tip of tongue and ask patient to raise the same to rugae area and swallow Two elastic swallow : place one on the tip of tongue and other on dorsum of tongue in the midline and ask to swallow Tongue hold exercise : ask patient to place the same on designated spot over a definite period of time with lips closed, ask patient to swallow with elastic in the designated position and lips apart Hold pull exercise : tip of the tongue contacts the palate in the midline and the mandible is gradually opened. This allows the stretching of the frenum to relieve a mild tongue-tie
Exercises of masseter muscles	Ask patient to clench his teeth, count up to 10 in his mind and then relax them Repeat over time until masseter muscles feel tired
Exercises of pterygoid muscles	In case of disto-occlusion cases, ask patient to protrude the mandible as much as possible then retracted Repeat until muscles feel tired

Limitation : Exercises are not known to drastically alter any bone growth pattern, not a substitute for corrective orthodontic treatment, patient compliance is extremely important, if not done correctly, can be counter productive

Removal of soft or hard tissue impediments in the pathway of eruption

Retained deciduous tooth / teeth	More common today due to the shift from hard, detergent diet to a soft diet Generally, retained deciduous teeth are observed in the mandibular anterior region, with the permanent teeth erupting lingually or in the maxillary anterior and buccal regions, with the permanent teeth erupting labially / buccally Unilateral presence of such retained teeth results in a midline shift thus compounding an arch space deficiency in a quadrant Extraction of the retained deciduous teeth would resolve the malocclusion completely or decrease its severity
Supernumerary teeth	Impede the eruption of permanent teeth in rightful place Timely extraction
Fibrous / bony obstruction of the erupting toothbud	If the contralateral tooth fails to erupt even after 3 months, there should be a cause for concern and a radiographic assessment Surgical intervention may be required Excision of the fibrous soft tissues is done or removal of any overlying bone over the unerupted A zinc oxide eugenol dressing is recommended for a period of 2 weeks postsurgically

Resolution of crowding

In the anterior segment the incisal liability plays an active role
Mechanisms by which incisal liability is resolved :

Interdental spacing	Presence of interdental spaces and primate spaces during the deciduous and the early mixed dentition provide space for the accommodation of larger permanent incisors as they erupt Generally 2-3mm As the lateral incisors erupt they bring about a lateral shift of the deciduous canines in the mandible only, into the primate spaces if present, resulting in a further resolution of crowding
Intercanine arch growth	Generally 3-4mm, greater in maxilla Get affected on premature loss of deciduous canine or on developing of a deep bite
Labial positioning of the incisors	Generally 1-2mm

Holding of the Leeway space of Nance would also allow more space so as to allow adjustments for anterior crowding. The space that can be obtained by holding the Leeway space is 0.9 mm in the maxilla and 1.7 mm in the mandible per quadrant
In the posteriors the Leeway space of Nance helps in the resolution of any crowding

Management of crowding

Observation
Disking of primary teeth
Extractions and serial extraction
Corrective orthodontic referral

Observation

50% chances of resolution of crowding in permanent dentition if the physiological spaces are between 2-3mm and no crowding occurs if these spaces >6mm
Regular recall and review regimen

Disking of primary teeth

Effective mechanism to resolve anterior crowding
Generally done if the space required for the resolution of anterior crowding is not > 4 mm
Disking is done of the mesial surfaces of the deciduous canines, followed by that of the distal surfaces of deciduous canines, if more space is required
If still more space is required after recall and review, then mesial surfaces of the deciduous first molars can be disked
Topical fluoride application after disking is a must to ensure that child does not suffer from any sensitivity

Extractions and serial extraction

Planned and sequential removal of the primary and permanent teeth to intercept and reduce dental crowding problems
Usually initiated in the early mixed dentition, to avoid development of a fully matured malocclusion in the permanent dentition
Increases the amount of space available for the erupting permanent teeth and thereby enables them to assume a more normal position and occlusal and spatial relationship
If done properly in carefully selected patients reduces time, the cost of the treatment, discomfort to the patient and time lost by the patient and the parents

Rationale

Class I : though there is tooth size arch length deficiency the neuromuscular activity is within normal limits and expansion of the arches would make the positioning of teeth unstable. Therefore, the guidance of occlusion would be the best treatment option
Class II : here is a definite change in the muscular function away from the normal; a change in position of teeth on expansion may be a more valid treatment

Indications

Class I malocclusion with arch size-tooth size deficiency of 5mm or more per quadrant
Unilateral or bilateral arch length deficiency indicated by

Midline shift of mandibular incisors due to displaced lateral incisors
Premature loss of deciduous canine
Abnormal canine root resorption
Canine being blocked out labially
Mandibular and maxillary anterior teeth that are proclined (bimaxillary protrusion), could be associated with crowding
Gingival recession on the labial aspect of mandibular anterior
Ectopic eruption
Extensive proximal caries and subsequent mesial migration of the teeth distal to the carious lesion
Premature loss of deciduous tooth and lack of subsequent space maintenance
Deleterious oral habits
Improper proximal restorations
Tooth ankylosis

Contraindications

Mild to moderate crowding : tooth size arch length deficiency < 5 mm per quadrant
Class II division 2 and Class III malocclusions
Spaced dentition
Congenital absence : anodontia/oligodontia
Extensive caries involving permanent first molars, which cannot be conserved
Open bite and deep bite, which should be corrected first

Diagnosis : study models, radiographs, photographs

Study models	Assess the dental anatomy of teeth Assess the intercuspation of teeth Assess the arch form and curve of occlusion Evaluate occlusion Undertake model analysis: Carey’s analysis, arch perimeter analysis and mixed dentition analysis Between and post-treatment assessments
Radiographs	Detection of congenitally missing teeth, supernumerary teeth Detection of any bony pathosis Enable to undertake radiographic mixed dentition analysis, which is more accurate To assess the stage of root development and the possible eruption pattern To determine the dental age of the patient To assess the different relationships between craniofacial structures using cephalometric analysis
Photographs	For self-evaluation of the case pre, mid and post-treatment For showing the patient the progress in treatment as well as for patient motivation To observe for any changes extraorally in front, right lateral and left lateral aspects mid and posttreatment To assess any muscular hypo- or hyperactivity

Procedure

Tweed’s method	Deciduous first molars are extracted at 8 years Deciduous canines are maintained to slow down the eruption of permanent canines As soon as the first premolars are in the advanced eruptive stage wherein their crowns are above the alveolar bone — radiographically, the deciduous canines along with the first premolars are extracted
Dewel’s method	At about 8½ years of age the deciduous canines are extracted so as to create space for the self-alignment of crowded anteriors At about 9½ years of age, as the incisor crowding would have got resolved and the first premolar would have had their roots developed up to their half level or more radiographically, the deciduous first molars are extracted so as to allow the first premolar to erupt prematurely into the oral cavity At about 9½ years of age, as the incisor crowding would have got resolved and the first premolar would have had their roots developed up to their half level or more radiographically, the deciduous first molars are extracted so as to allow the first premolar to erupt prematurely into the oral cavity
Nance’s method	Modified Tweed’s method Extraction of deciduous first molars at about 8 years of age, which is followed by the extraction of the first premolars and deciduous canines
Grewe’s method	Class I malocclusion with premature loss of a mandibular deciduous canine Extract remaining deciduous canines if midline shift to the side of the premature loss of deciduous canine and where the arch length discrepancy is 5 to 10 mm per arch The deciduous first molars should be extracted next, if the first premolars have their roots more than half developed If the roots of the first premolars are not developed more than half then one should delay the extraction of deciduous first molar The first premolars should be extracted as they emerge Class I malocclusion with severe mandibular anterior crowding Extract the deciduous canines if arch-length deficiency in excess of 5 mm per quadrant The deciduous first molars are extracted next on completion of at least half of first premolar root formation and the extraction of first premolars follow as they erupt into the oral cavity Class I malocclusion where minimal mandibular anterior crowding is 6-10mm per arch deficiency The deciduous primary first molars are extracted when the roots of first premolars are more than half formed, as this would in turn result in premature eruption of the first premolar As soon as the first premolars erupt into the oral cavity, these are extracted followed by deciduous canines If there is bound to be eruption of permanent canine before that of the first premolar, then the deciduous canine is extracted first, followed by the extraction of the deciduous first molar and enucleation of the first premolar Dental Class II with normal overjet When there is no crowding in the mandibular arch but, there is crowding in the maxillary arch, which can be eliminated The deciduous maxillary canines are extracted followed by the deciduous first molars This is followed by the extraction of maxillary first premolars as they erupt The deciduous second molars are kept under review so that they may be extracted to allow buccal interdigitation Dental or skeletal Class II with slight but minimal overjet If crowding is present in both the maxillary and mandibular arches Extraction of maxillary deciduous first molars and mandibular deciduous second molars and then enucleation of mandibular second premolars The maxillary first premolar and maxillary deciduous canine are extracted when the maxillary first premolars emerge into the oral cavity Some form of corrective orthodontic intervention is required

Advantages

More physiologic treatment as teeth are guided into normal positions using physiologic forces
Reduced duration of fixed treatment
Lesser retention period required
Results are more stable

Disadvantages

Good clinical judgment is required. No single approach can be universally applied
Treatment time is prolonged over 2-3 years
Patient cooperation is very important
Tendency to develop tongue thrust as extraction spaces close gradually
Extraction of buccal teeth causes deepening of the bite
Residual spaces can remain between the canine and second premolar
Some amount of fixed appliance therapy is usually required at the end of serial extraction

Corrective orthodontic referral

Cases treated by serial extraction as well as severe crowding cases and those having severe dentoskeletal malocclusions

Interception of developing skeletal malocclusions

To decrease its severity and at times even resulting in a normal occlusion
These changes are brought about by myofunctional therapy, which more appropriately is known as Functional Jaw Orthopedics today

Interception of Class II malocclusion	Generally occurs as result of either increased maxillary growth or decreased mandibular growth or a combination of the same Face bow along with the headgear retards excessive growth of the maxilla Functional appliances bring about the anterior positioning of the mandible
Interception of Class III malocclusion	Generally results due to a deficiency in maxillary growth or excessive mandibular growth or a combination of the same Frankel’s III appliance is used for promoting growth of the deficient maxilla Chin cup is generally used to restrict mandibular clockwise growth

Indications : Mandibular anterior crowding, Class II Division 1 and 2, Anterior open bite, Deep bite, Mild Class III/ Pseudo Class III, Tongue thrusters, thumb sucking and oral breathing habits
Contraindications : Posterior cross bite—which is uncorrected, Severe Class III, Complete nasal obstruction, Non-cooperative child/parent
The appliance should be inserted for a minimum of one hour daily during the day and also be worn while sleeping