INDIAN DENTAL ACADEMY
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Mixed Dentition Orthodontic Treatment
•Introduction•Rationale for Early Treatment•Benefits of Early Treatment•Difficulties of Early Treatment•Treatment Planning in Mixed Dentition•Treatment Modalities
“The developmental period after permanent first molars and incisors have erupted and before remaining deciduous teeth are lost”
AAO recommends visit to an orthodontist
by Age of 7
Favourably developing occlusion at this stage has 3 characteristics:
• Molar relationship is usually endon and typically transforms into a class I during the transition from a mixed dentition to permanent dentition
• Nicely aligned permanent incisors often sporting their mamelons with short clinical crown and a 1-3 mm of overbite and overjet
• A small space either mesially or distally to a permanent canine
Rationale for Early Treatment
•Some malocclusion can be prevented or intercepted
•Diphasic treatment is considered more logic and sensible
•During phase I, craniofacial skeletal growth is controlled and morphology improved so that later tooth positioning is easier
Rationale for Early Treatment
•One may be able to remove etiological factors, enlist natural growth forces, and provide differential crown response and obtain a balanced profile prior to eruption of most permanent teeth
•Clinician can utilise growth better in the young and there is more growth available
Benefits of Early Treatment
•Possibility of achieving better results
•Early treatment of serious, deleterious habits is easier than treatment after years of ingrained habit reinforcement
•Psychological advantage to early treatment in some children
•Younger patients are often more cooperative and attentive
Difficulties of Early Treatment
• Diphasic treatment may lengthen chronologic treatment time
• Early diagnosis and treatment planning are more tentative and the periodic cephalometric reassessment is a necessity
• Increased cost factor
Treatment Planning in
Conditions that SHOULD BE treated……
•Loss of primary teeth endangering the available space in the arch (space maintainer)
• Space closure that had occurred due to premature loss of primary teeth ( Space Regaining)
• Supernumerary teeth that may cause malocclusion
Conditions that SHOULD BE treated……
•Malocclusion due to habits
•Neutroocclusion with extreme labioversion of the maxillary anterior teeth
Conditions that SHOULD BE treated……
• Class II (distoocclusion) cases of functional type
• Class II (distoocclusion) cases of dental type
• Class II (distoocclusion) cases of Skeletal type
Conditions that SHOULD BE treated……
• Localised spacing between the maxillary central incisors for which orthodontic therapy is indicated
• Malposition of a teeth that interfere with normal development of occlusal function
Conditions that MAY BE treated……
•Class II malocclusion of a skeletal type particularly if diphasic treatment is indicated
•Class III malocclusion where early treatment is feasible
•Gross disharmonies of apical bases
•All malocclusions accompanied by extremely large teeth
I. Treatment of Non Skeletal Problems
II. Treatment of Class II malocclusion
III. Treatment of Class III malocclusion
Treatment of Non Skeletal problems…
Space ProblemsEruption Problems
Occlusal relationship Problems
Transitional Appliances In the mixed dentition 2.5 mm per side can be gained in the mandibular arch and about 2 mm per side can be gained in the maxillary arch ( Moyers et al 1976) This space has to be maintained and 2 appliances that are used as holding appliances:
1. Transpalatal arch 2. Lingual arch
Transpalatal Arch•Extends from one maxillary first molar along the contour of the palate to the molar on the opposite side.
•Major function in the mixed dentition is to prevent the mesial migration of the upper I molars during the transition from the deciduous molars to the second premolars. www.indiandentalacademy.com
•Also capable of producing molar rotations and changes in root torque by sequential unilateral activation of the appliance.
•Also used for molar stabilization and anchorage.
•Usually used in the mandible as part of the early treatment protocol. Has a function similar to TPA.•It extends along the lingual contour of the mandibular dentition from the I molar of one side to the other.
•Optional adjustment loops can be placed in the region of II deciduous molars.
•In contrast to TPA the lingual arch is usually removed after the eruption of II premolars is completed.
Space Problems(Moderate severity)
Missing primary teeth with adequate Space – Space Maintenance
Early loss of primary teeth presents a potential alignment problem because drift of permanent or other primary teeth is a likely sequela. Hence space must be maintained.Many treatment are successfully used for specific situations …..
Band and loop space maintainer
• unilateral fixed appliance
• indicated in posterior segments
• mostly used to maintain space of primary first molar before eruption of permanent first molar
• Also used to maintain the space of either a primary first or second molar after perm first molar has erupted
Distal shoe space maintainer
• Appliance of choice when a primary second molar is lost before eruption of permanent I molar
• Consists of a metal or a plastic guideplane along which the permanent molar erupts.The guideplane must extend into the alveolar process so that it contacts the permanent first molar approximately 1 mm below the mesial marginal ridge before it emerges from the bone.
Lingual Arch Space maintainer • Attached to bands on the
primary II or permanent I molars and contacting the cingula of the maxillary or mandibular incisors, prevents the anterior movement of the posterior teeth ad posterior movement of the anterior teeth
•Indicated when multiple primary posterior teeth are missing and permanent incisors have erupted
Partial Denture space maintainer
• Most useful in bilateral space maintenance when more than 1 tooth has been lost per segment
• Also indicated in posterior space maintenance in conjunction with anterior teeth for esthetics
Localized Space loss (3 mm or less) – Space Regaining
Space Problems(Moderate severity)
Maxillary Space Regaining• Permanent maxillary I molars can be tipped
distally to regain space with either a fixed or removable appliance but bodily movement requires a fixed appliance.
• A removable appliance is one with Adam`s clasp and helical finger spring adjacent to the tooth to be moved
• Tooth can be moved upto 3 mm during 3-4 months of full time wear
• The spring is activated approximately 2 mm to distalize 1 mm movement per month
• When bilateral maxillary space regaining is needed either by tipping both molars or by bodily movement, an extra oral force via a face bow to the molars is effective
• The force is directed specifically to the teeth to be moved
• Approximately 100 g of force per side is appropriate
• 14 – 16 hrs of wear per day is minimal
Mandibular Space Regaining• The mandibular appliances are not satisfactory as it
is prone to breakage and may be difficult to retain• If space has been lost on 1 side of the arch, the
appliance of choice is a removable lingual arch incorporating a loop that can be opened to provide the distal force
• An alternative fixed appliance is the lip bumper, which is a labial appliance fixed to tubes on the molar teeth. The appliance presses against the lip which creates the distal force to tip the molars posteriorly
Maxillary Midline Diastema
• Esthetic compliant• Position of central incisors that inhibit
eruption of lateral incisor or canine • Diastema of more than 2mm
A small diastema present in children is not necessarily an indication for orthodontic treatment
Major indications for diastema closure :
• A small but unesthetic diastema (2 mm or less) can be closed by tipping the central incisors together
• A maxillary removable appliance with clasps, finger springs and possibly an anterior bow is a successful appliance
• More large unesthetic diastemas will require bodily repositioning of the incisors where teeth can be moved along a segmental arch wire that is placed in bonded brackets on the incisors and the force is provided by an elastomeric chain
Midline Discrepancy from intra arch asymmetry
• This is a potential problem which is usually exhibited as a shift of the dental midline to one side because of premature loss of 1 primary canine
• If archlength is adequate the incisors can be aligned to their optimal location using removable appliance and finger spring
• If a bodily drift has accompanied the midline change then the anteriors must be bonded and aligned with an arch wire.The force is generated by a coil spring
• Retention will be needed till permanent teeth eruptwww.indiandentalacademy.com
Space Problems(Greater severity)
Severe Crowding of more than 4 mm
Crowding Most common type of malocclusion in mixed dentition is crowding.They usually present with class I molar relationship or a tendency towards either Class II or class III malocclusion.
“A disparity in the relationship between the tooth size and jaw size, which results in imbrication and rotation of tooth” (AJO 1983 May, McNamara)
1. Hereditary Crowding
2. Environmental Crowding
3. Late lower arch Crowding
Types of Crowding:
Serial Extraction “The sequential removal of deciduous teeth to facilitate
the unimpeded eruption of permanent teeth.”
Procedure began in Europe Advocated by No. of individuals.
•Hotz (1948,1974)•Kjellgran(1948)•Terwilliger (1950)•Lloyd (1953)•Palson(1956)•Dewell(1954,1959,1967)•Ringenberg (1964)
*May be indicated when it is determined with a fair degree of certainty and there will not be enough space in the jaws to accommodate all the permanent teeth in their proper alignment.
*Another indication is the early loss of one or both mandibular canines and the resultant midline discrepancy.
*The chances of success with this treatment are relatively good with class I malocclusion and if they are undertaken in Class II or Class III malocclusion, great caution must be taken not only in solving the emerging intraarch problem but also the existing interarch relationship. *Usually are not indicated in situations of extreme skeletal imbalance
Ringenberg(1964)cites a discrepancy of 7 mm or greater for Serial Extraction. Profit(1986) Is indicated with a space discrepancy of 10 mm or greater.
Vanarsdall(1992) May be combined with RME in certain patients with significant arch size discrepancy who also have narrow tapered maxilla and negative space present in the corner of mouth during smiling.
Methods of Serial Extraction
1. Dewell`s method CD4
2. Tweed`s method D4C
3. Nance`s method D4C
EXTRACTION OF PRIMARY CANINES:
To relieve incisal crowding
Radiographic Examination A Crescent pattern of resorption on the mesial of the primary canine roots. Signifies that premolars are emerging favourably ahead of permanent canines. None of the unerupted permanent teeth have reached ½ root length.
EXTRACTION OF PRIMARY I MOLARS:
Incisal crowding has improved, overbite has increased and extraction site is reduced in size.
Radiographic Examination: Reveal that first bicuspids have reached ½ root length, and is favourable for extraction of Ds to speed up the eruption of 4s.
EXTRACTION OF FIRST BICUSPID:
When permanent canines have developed beyond ½ root length, to accelerate their eruption the first bicuspids are extracted.
As a result of Serial Extraction there is an increased deep overbite with distoaxial inclination of canines, mesioinclination of second bicuspids, Clas I molar relationship, improved alignment of the incisors and residual spaces at extraction sites.
After mechanotherapy is completed, there will be an ideal occlusion with normal overbite, overjet, parallel canine & bicuspid roots.
• Ankylosed primary teeth• Supernumerary teeth• Ectopic eruption
Ankylosed primary teeth• They constitute a potential alignment problem
for the permanent teeth • Although usually are resorbed in normal
manner, occasionally are not exfoliated on schedule and are retained between the tooth and the hard tissue in the cervical region
• Management consists of maintaining it until an interference with eruption or drift of other teeth begins to occur, then extracting it and placing a space maintainer if needed
Supernumerary teeth• Can distrupt both the normal eruption of the
other teeth and their alignment if eruption does occur
• Most common location is the anterior maxilla• Treatment is aimed at extraction of the
supernumeraries before the problems arise or minimizing the effect if teeth have already been displaced
Ectopic eruption• Eruption is ectopic when a permanent tooth
causes either resorption of a primary tooth other than the one it is supposed to replace or resorption of an adjacent permanent tooth
• Alignment problem results if the primary tooth is lost prematurely or if the underlying permanent tooth is blocked from erupting
• After a period of watchful waiting, and if the blockage persists for 6 months the basic approach is to move the ectopically erupting tooth away from the tooth it is resorbing
• The most common ectopically erupting permanent tooth other than the I molar is a permanent maxillary canine with the resorption of permanent lateral incisor roots
• Radiographically, when mesial inclination of the erupting permanent canine is detected and no incisor root resorption is noted, the treatment of choice is to extract the overlying primary canine
Occlusal relationship problemsDental cross bites caused by displacement of teeth result from bilateral constriction of maxillary arch and shift of the mandible to one side
Three basic approaches to treatment of posterior cross bite are:1.Equilibration to eliminate mandibular shift2.Expansion3.Repositioning of individual teeth
•Treatment is with a split-plate type of removable appliances:
1. A banded or bonded jack-screw appliance is commonly used
2. W arch or quad helix are reliable and easy to use
Expansion should continue at the rate of 2mm per month until cross bite is over corrected
It requires 2-3 months of active treatment and 3 months of retention
Quad helix is indicated in a combination of cross bite and finger sucking habit
Habits and open bites
• Most Children engage in some form of non nutritive sucking
• Intervention is usually not indicated until 5 years of age
• As long as sucking stops before the eruption of permanent incisors, most of the dental changes resolves spontaneously
• At the time of eruption of permanent incisors, Counseling can be given
Habits and open bites
If counseling does not work, the patient can be fitted with a cemented reminder appliance that consists of maxillary lingual arch and a crib constructed of soldered wire so that it is difficult to insert the thumb into the mouth
The open bites associated with sucking often resolves after sucking stops and the remaining permanent teeth erupt
Open bites that persists almost have a significant skeletal component
The problem may result from :1. Reduced lower facial height and lack of
eruption of posterior teeth2. Or over eruption of anterior teeth
Treatment•Removable bite plate appliances to reduce the overbite. Can be used for patients who have less than normal eruption of posterior teeth.
•An anterior bite plate is incorporated into a removable appliance so that mandibular incisors occlude with the plastic plane lingual to maxillary incisors.
• This prevents the posterior teeth from occluding and encourages their eruption.Full time wear appliance.
•Bite plate must continue to be worn after proper vertical dimension is established
Anterior Bracket Placement
•Since only permanent incisors are erupted, placement of brackets only in these teeth are indicated.
•The alignment can be achieved through a relatively simple sequence of arch wires.
•The utility arch involves the placement of bands on the first molars, a transpalatal arch can be used to anchor the utility arch posteriorly.
Anterior Bracket PlacementUtility arch :
•In significant no. of patients with tooth size arch size discrepancy patients irregularities exists in alignment of anterior teeth.
•This also occurs as a consequence of RME in mixed dentition.
Types of Utility Arch
Based on their use ( McNamara 1986)
1.Passive Utility Arch 2.Intrusion Utility Arch 3. Retraction Utility Arch4. Protraction Utility Arch
Early treatment of
Class II Malocclusion
Mixed treatment goals often focuses on skeletal rather than dental correction.To design a treatment plan the clinician must understand the growth and development pattern and know the effects of chosen treatment modality.
Growth affects orthodontic treatment usually favourable but sometimes unfavourable. When and how much growth will occur is completely unpredictable.
Some useful facts about jaw growth in Mixed Dentition…*
Between ages of 5-10 years, the intercanine dimension may increase by 3 mm.After the age of 10, there are no changes in the width
The space in the maxillary arch from molar to molar increases by 2 mm.In the mandible, there is a decrease of 2 mm to an increase of 4 mm.
The palatal midline suture closes at about the age of 13 in girls and 16 in boys. The frontopalatal suture closes at around age 2.
Growth rates peak for girls at age 13 and for boys at age 15.
*Dr.Gerald Nelson, Orthodontic dialogue 1997 issue Vol 9www.indiandentalacademy.com
Many treatment approaches are currently available to the orthodontist for altering the occlusal relationships typically found in class II malocclusions.Each treatment approach however differs in its effect on the skeletal structure, sometimes accelerating or limiting the growth of various structures involved Treatments:
•Extraoral Traction Appliances
•Functional Jaw Orthopaedics
•Arch Expansion Applianceswww.indiandentalacademy.com
Components of skeletal Class II malocclusion
•Prognathic maxilla with orthognathic mandible•Retrognathic mandible with orthognathic maxilla•Combination of both•Vertical problems – increased maxillary excess
Maxillary skeletal problemsMaxillary skeletal protrusion: Most common treatment is extra-oral traction. These appliances are divided into 2 types: i) Facebows ii) Head gears Facebows: Facebows attached to tubes on the upper first molar bands Head gears attached directly to the arch wire or to the
auxiliaries connected to the arch wire ( Berger 1992).
Cervical facebow also called low pull facebow. Mostly used in patients with decreased vertical dimension. Innerbow attached to buccal tube of the I molar
Outerbow connected to strap that extends to cervical region and anchored against dorsal aspect of neck. Outerbow Lies above the plane of occlusion to direct the force through the center of resistance and prevent distal tipping of the molars.Cervical traction increases the vertical dimension by extrusion of molars.
A high pull facebow is used in individuals in whom increases in vertical dimension are to be avoided.The facebow is anchored to occipital anchoring unit to produce a more vertically directed force.It allows automation of the mandible and maximizes the horizontal expression of mandibular growth (Tweed1966). A straight pull face bow is a combination of cervical and head cap
Maxillary skeletal Retrusion
• It is extremely difficult to treat directly, except through orthognathic surgery, and usually
• No attempt is made to correct maxillary skeletal retrusion in mixed dentition
• Occasionally retrusion is treated indirectly by using
appliances such as posterior bite block or a vertical pull chin cap that produce a slight upward and forward movement of the maxilla and a counter clockwise rotation of mandible(Dellinger1973,Pearson1978)
Maxillary deficiencyTransverse Maxillary Constriction
• Skeletal Maxillary constriction is distinguished by a narrow palatal vault.
• Can be corrected by opening the midpalatal suture, which widens the roof of mouth and floor of nose
• Growth in this suture is an important mechanism for normal widening of arch
•The corner stone of early expansion treatment in patients with arch length discrepancy problems is RME. •RME is most essential component of mixed dentition treatment protocol.
•Of all the areas of craniofacial complex, the most readily adaptable is the transverse dimension of maxilla. expansion is produced by applying a lateral force against the posterior maxillary dentition producing a separation of mid-palatal suture.
•According to Nelson (1972,1982), RME is easily achieved in a growing individual. The acrylic has an additional advantage of acting as a posterior bite block that covers the occlusal surface of posterior dentition and prevents the extrusion of posterior teeth.It is used in patients with steep mandibular angles.
•A transpalatal width of 33 – 35 mm is considered ideal for a patient during mixed dentition period (Spillane & McNamara 1989)
•Rapid palatal expansion produces an increase in the maxillary arch perimeter at the rate of 0.7 times the change in I premolar width. In treatment planning, it would be helpful to predict the gain in arch perimeter for a given amount of transverse expansion ( Nanda , Adkiins AJO – 1990 March).
•Although the use of RPE procedures in the primary and mixed
dentition has been reported in the literature, and the clinical
indications have been proposed (Bell, 1982; Bishara et al., 1987; Nicholson et al., 1989; Halazonetis et al., 1994), relatively little has been published concerning the specific cephalometric alterations induced by this appliance.
•Haas (1970) stated that once the mid-palatal suture opens, the maxilla always moves forward and downward, and this causes a downward and backward rotation of the mandible, which decreases the effective length of the mandible and increases the vertical dimension of the lower face.
•Wertz (1970) suggested from his analysis of lateral cephalograms
that the maxilla drops down consistently, but rarely moves forward
significantly. However, he had no control group against which to assess the vertical changes.
•This was later confirmed by da Silva et al. (1991), who found that the maxilla did not show any statistically significant alterations in the anteroposterior position over the 14–16 days of appliance activator. The maxilla displayed a tendency to rotate downward and backward . The mandible rotated down and posteriorly.
•McNamara (1993) in a study of the effects induced by a RPE appliance
observed that widening the maxilla lead to a spontaneous forward
posturing of the mandible during the retention period and that a spontaneous correction of Class II relationship can be found after 6–12 months.
• Velàzquez et al. (1996) in a long-term study regarding the effects of RPE reported that the modest, but potentially unfavourable changes induced by the RPE device, such as an open bite or mandibular posterorotation, are reversible. They found that, following termination of orthodontic treatment, these undesirable effects were almost completely resolved.
•The appliance of choice is a bonded RME appliance. It incorporates a hyrax type screw into a framework made of wire and acrylic, is used to separate the halves of maxilla.
The screw is activated ¼ turn (90) per day (0.22 mm) until the lingual cusps of upper posterior teeth approximate the buccal cusp of lower posterior teeth.
After the active phase of expansion is completed, the appliance is left passively for 4-5 months to allow for a reorganization of the midpalatal suture.at the end of treatment time appliance is removed and patient is given a removable palatal plate .RME affects een the circumzygomatic and circummaxillary sutural systems (starnbach et al 1966)
Active expansion produces mid line diastema between two central incisors .a mesial tipping of maxillary central and lateral incisors occurs .
Mandibular Expansion AppliancesThe Schwarz appliance :Indicated in patients with mild to moderate crowding in lower anteriors.
• It is activated once per week ,producing 0.25mm of expansion. • Treatment is done for 3 or 4 months ,depending upon incisor crowding ,producing 3-4 mm of arch length anteriorly.• After active treatment appliance left passively for 6 months.
It is horse shoe shaped appliance that fits along lingual border of mandibular dentition .a midline expansion screw is incorporated into the acrylic with ball end clasps in the interproximal spaces between deciduous and permanent molars
LIP BUMPER It is useful patients who have very tight or tense buccal and labial musculature.it lies away from the dentition and shields it from the forces of adjacent soft tissues It is an removable appliance that attaches to buccal tubes on first molar .
It is worn on a full time basis
It not only increases arch length through passive lateral and anterior expansion but also serves to upright lower molars distally adding to arch length increase .
Maxillary dentoalveolar problems
1. simple2. complex
Divided into two types
Simple problems : Usually flared or retruded incisors.
Management :o flared incisors i. retraction using retraction utility arches ii. or high pull head gear or straight pull
head gear combined with ‘J’ hooks that are attached to the arch wires anteriorly or by using a closing arch supported by headgear (Berger 1992)
o Retruded incisors protraction utility arches
They involve protrusion of the entire maxillary dental arch relative to the skeletal portion of the maxilla. The goal o f treatment is either to retract the upper anterior teeth following removal of upper 2 premolars or to move the maxillary dentition en masse in a distal direction.
This goal is achieved through a no. of treatment options ….
1. Extraoral traction like cervical, straight pull and high pull face bows as well as high pull, straight pull and low pull head gear with ‘J’ hooks. Use of interlandi head gear provides an additional treatment option with variable direction of force. It is also possible to attach a high pull head gear to the upper arch and the straight pull head gear to the lower arch simultaneously
2. Distallizing plates (Cetlin’s appliance): These plates fit against maxillary dentition and produce a posterior force against the first molars.It’s a Full time appliance and can be used along with cervical or high pull face bows in night times.finger springs on the plate tip the crown distally, the facebow produces distal root torque to maintain an upright position of molars. They are also useful in regaining space that was lost due to premature loss of II deciduous molars.
3. Distallizing magnets: This procedure is used both in late mixed dentition and permanent dentition. An assembly containing repelling magnets is placed into the molar tube on the upper I molars and magnets are placed in repelling position y ligating a sliding yoke to an eyelet on the premolars. Activation done every done 2-4 weeks produces a distalizing force which results in posterior movement of the upper molar. 25% anchor loss is seen (Giannelly 1992)
4. Ni-Ti coils: They can be incorporated into an appliance system similar to magnets.they produce a continuous force of 100-300 g bilaterally.After achieving the molar distallization to a slightly over-corrected position and they are stabilized with Nance holding arch or a passive utility arch.The premolars and the canine are allowed to drift distally due to the pull of transseptal fibers between adjacent teeth.After 3 or 4 months e-chain is used to distallize the premolar and canine.A retraction utility arch or a closing loop arch is then used to complete anterior space closure.
Mandibular skeletal problems
Mandibular Dentoalveolar Retrusion: Treated by lip bumper in individual who have very tight cheek and lip musculature.
Passive utility arch is effective in partially shielding the eruptive dentition from cheek musculature.
Mandibular Skeletal retrusion
Retrognathic mandible in the growth period is treated by functional jaw orthopaedic appliances
1. Activator2. Bionator3. Frankel II4. Herbst5. Twin Block
Activator According to Anderson & Haupl, it induces musculoskeletal adaptation by introducing a new pattern of mandibular closure. When the mandible is moved forward, it results in stretching of elevator muscles of mastication, which starts contracting thereby settingup a myotactic reflex and causes advancement of mandible. In the first week, patient is asked to wear for 2-3 hrs /day in daytime followed y 3 hours during the day as well as night time. After 1 week of usage, trimming plan is developed.
Used in patients with extremely short lower anterior facial heights. In these patients there is no adequate vertical space for positioning lower labial pad of Frankel II. It not only brings the mandible in forward position but also increases the vertical dimension through differential eruption of posterior teeth.
Herbst Appliance •Developed by Emil Herbst. •Uses a telescopic mechanism and encourages forward repositioning of the lower jaw as the patient closes into occlusion. •Pancherz 1982 & McNamara 1990 have shown that both skeletal and dental adaptations are produced with this appliance. •This was previously used in the mixed dentition period but now primarily used as an appliance in permanent dentition.
Frankel II Applaince It is a tissue borne appliance, the base of operation is in the maxillary and mandibular vestibule and the appliance has a direct and primary effect on the neuromuscular system. It is used an exercise device by retraining or reprogramming the CNS. It interrupts normal pattern of muscle activity and ultimately produces an environment in which skeletal and dental arch change occur. It is the appliance of choice in treatment of patients with severe neuromuscular imbalance and skeletal discrepancies. As this is a tissue borne appliance, maximum skeletal change is achieved with minimal unwanted tooth movement. www.indiandentalacademy.com
Twin Block Appliance This appliance has been shown to produce increase in mandibular length as well as a variation in lower anterior facial height. Trimming of the posterior bite blocks of the appliance facilitate the eruption of the lower posterior teeth in patients with a deep bite and increased Curve of Spee. It is a full time wear appliance and speaking is not a problem. Active phase of 6-9 months followed by a supportive phase of 3-6 months for molars to erupt into occlusion. Average treatment time is 18 months including retention period.
Related articles: 1.Keeling et al: Reveal that both bionator and head-gear treatments corrected Class II molar relationships, reduced overjets and apical base discrepancies, and caused posterior maxillary tooth movement. The skeletal changes, largely attributable to enhanced mandibular growth in both headgear and bionator subjects, were stable a year after the end of treatment, but dental movements relapsed. (Am J Orthod Dentofacial Orthop 1998;113:40-50.) 2.Ghafari et al – comparison of head gear Vs Frankel in early treatment of Class II div 1 malocclusion – Randomised Clinical trial The results indicate that both the headgear and function regulator were effective in correcting the malocclusion.A common mode of action of these appliances is the possibility to generate differential growth between the jaws. The extent and nature of this effect, as well as other skeletal and occlusal responses differ. Treatment in late childhood was as effective as that in midchildhood. This finding suggests that timing of treatment in developing malocclusions may be optimal in the late mixed dentition, thus avoiding a retention phase before a later stage of orthodontic treatment with fixed appliances. However, a number of conditions may dictate an earlier intervention in the individual patient.(Am J Orthod Dentofacial Orthop 1998;113:51-61.)
3.Treatment effects of the twin block appliance: A cephalometric studyChristine M. Mills, DDS, MS,a and Kara J. McCulloch, DMDVancouver, British Columbia, Canada, and Seattle, Washington
A clinical study was undertaken to investigate the treatment effects of a modified Twin Block appliance. Results indicated that mandibular growth in the treatment group was on average 4.2 mm greater than in the control group over the 14-month treatment period. In addition, some dentoalveolar effects in both arches contributed to the overjet correction. No statistically significant increase in the SN mandibular plane angle occurred during treatment and, in general, the magnitude and direction of the skeletal changes were found to be quite favorable. (Am J Orthod Dentofacial Orthop 1998;114:15-24.)
Early treatment of
Class III Malocclusion
Frankel III Appliance
• It is a functional appliance designed to counteract the muscle forces acting on the maxillary complex. According to Frankel, the vestibular shields in the sulcus are placed away from alveolar buccal plates of the maxilla to stretch the periosteum and allow for forward development of maxilla. The shields are fitted closely to the alveolar process of the mandible to hold or redirect growth posteriorly.
Ulgen et Firatili (AJO 1994) have found the best response to Frankel III with an increased overbite of 4-5 mm in early
mixed dentition. It is more successful in patients with class III malocclusion presenting with a functional shift on closure.
Chin cup therapy
• The main objective is to provide growth inhibition or redirection and posterior positioning of mandible. Most studies recommend an orthopaedic force of 300 to 500 g per side (AJO 1987). Patients are instructed to wear the appliance 14 hrs/day. A force is usually directed through the condyle or below the condyle.
Sugawara et al (AJO 1990) have compared the growth changes of patients after chin cup treatment with control subjects and reported that at age 17 the mid-face is more deficient in patients of control group than in those of treatment group.
Protraction Facemask •Consists of a fore head pack and a chin pad that are connected with a heavy steel support rod. A crossbow is connected to support this rod to which area attached rubber bands to produce a forward and downward elastic traction on the maxilla.• The mask system introduced by Mcnamara in 1987 as a bonded RPE in addition to a facial mask and elastics.
•Protraction with expansion can also be done using a banded palatal expander, a quad helix, etc.
•McNamara reports that the optimal time to intervene in an early class III patient is at the time of initial eruption of the upper central incisors.
Most patients who receive orthodontic care in mixed dentition will need a second phase of treatment in permanent dentition. Whether to render treatment in the mixed dentition requires careful case selection and a through diagnosis and treatment plan.
Benefits of Early class II Treatment : Progress Report of a Two face randomized Clinical Trial J.F.CamillaTulloch We conclude that, for children with moderate to severe Class II problems, early treatment followed by later comprehensive treatment on average does not produce major differences in jaw relationship or dental occlusion, compared with later one-stage treatment. The severity of the initial problem and the treatment time, surprisingly, are not important influences on the final outcome. Variability in skeletal growth pattern appears to be a major contributor to variability in treatment response. Differences in patient compliance, clinician proficiency, and, probably, other (yet-unidentified) clinical factors also must affect treatment outcomes. It is likely that the indications for early treatment can be refined in the future to permit better selection of those patients most likely to benefit from this type of intervention.(AJO Jan 1998)
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