Space Management

SPACE MANAGEMENTThe early loss of primary teeth can disrupt the integrity of the arch and can lead to problems that affect the alignment of the permanent dentition.

Miyamoto and colleagues observed the effects of the early loss of the primary teeth by measuring the crowding and malalignment in the permanent dentition and found that the children who had premature loss of one or more primary canines or molars were more likely to receive orthodontic treatment in the permanent dentition.

So space management is an important responsibility of the clinicians who are involved in monitoring the developing dentition , as the loss of arch length may lead to problems such as crowding , ectopic eruption , dental impaction , cross bite formation and dental midline discrepancies.

Dental arch length is the most important of dental arch dimensions in the developing individual. The maintenance of the dental arch length during primary , mixed and early permanent dentition is of great significance for the normal development of a functional , well- aligned and balanced adult occlusion.

The concept of space loss resulting from early exfoliation of teeth was described as early as 1880 by Davenport and Hutchinson. Loss of arch length occurs as a result of tooth migration , following premature loss of primary teeth , loss of interproximal contact as a result of decay , extraction or ankylosis of an adjacent tooth result in space loss because of mesial and to a lesser extent distal occlusal drift of the adjacent teeth. An important part of preventing iatrogenic malocclusion is the correct handling of the spaces created by the untimely loss of deciduous teeth.

So a clinician should meticulously manage the space. Space management is a general term that includes four subdivisions :

– Space maintenance – Space regaining – Space supervision

– Management of gross discrepancies

The goal is to prevent loss of arch length , width and perimeter by maintaining the relative position of the existing dentition.

DEVELOPMENT OF OCCLUSION :The supervision of the developing dentition and the initiation of preventive procedures , including space maintenance , require an understanding of the biogenetic course of the primary and permanent dentition. A review of the clinical studies by Baume informs about two consistent morphological arch forms of the primary dentition i,e spaced dentition and those without space.

CHANGES IN ARCH DIMENSION:From 4 years of the age until the eruption of the permanent molars the sagittal dimension of dental arch remains unchanged. A slight decrease in the dimension can occur either as a result of the mesial migration of the primary 2nd molar just after eruption or after development of proximal dental caries . Only minor changes in the transverse dimension of the maxillary and mandibular primary arches during period of 3-6 years.

Baume evaluated cast at time of eruption of permanent incisors. A transverse widening of mandibular arches occurred representing a physiological process to provide space for the erupting permanent incisors. This widening was brought about by lateral and frontal alveolar growth during the time of eruption of permanent incisors. Mean increase in maxillary arch width is greater than mandibular arch.(because of bigger teeth meee)

INTERCANINE WIDTH INCREASE:It increases at the time of eruption of maxillary central incisor and mandibular lateral incisor. By the time lateral incisors have completed their eruption , inter canine width has increased by about 3 mm in each of the maxilla and mandible. In maxilla , the intercanine width increases by another 1.5mm when the canine erupts.In mandibular arch there is limited potential for arch expansion and also the distalization is considered difficult. Therefore, conventional orthodontic

diagonosis is frequently based upon assessment of mandibular arch space requirement using arch-length analysis.

PRINCIPLES OF SPACE ANALYSIS:An accurate mixed dentition space analysis is one of the important criteria in determining whether the treatment plan may involve serial extraction, guidance of eruption , space maintenance , space regaining or just periodic observation of the patients ( smith et al, 1979; cunat 1982; lee-chan et al 1998, bishara and jakobsen 1998)

MIXED DENTITION ANALYSIS:

CONVENTIONAL SPACE ANALYSIS :The conventional or canine space analysis was first proposed by Nance in 1947. This analysis consists of comparing the amount of space available for the the alignment of the teeth to the amount of space required for proper alignment . This is accomplished by measuring arch perimeter from mesial of one first molar to the other, over the contact point of the posterior teeth and the incisal edge of the anterior. There are two basic ways to accomplish it. By dividing the dental arch into segments that can be measured as straight line approximations of the arch or by contouring a piece of wire to the line of occlusion and then straightening it out for the measurement. The space required is the summation of the mesiodistal widths of the erupted mandibular permanent incisors and the estimated mesiodistal widths of the unerupted permanent canines and premolars. The size of the unerupted permanent teeth can be estimated using radiographic method or using the prediction table or the combination of the both.

RADIOGRAPHIC METHOD : width of erupted tooth on cast = width of unerupted tooth on a radiograph Width of unerupted tooth Width of erupted tooth on radiograph

MOYERS MIXED DENTITION ANALYSIS :

The purpose of this is to analyse the amount of space available in the arch for erupting permanent canines and premolars. The mesiodistal width of four lower incisors is added and the amount of space available for 3,4 ,5 after incisor alignment is determined by measuring the distance between the distal surface of lateral incisor and mesial surface of first permanent molar. The predicted value of 3,4, 5 is seen through moyers prediction table.

TANAKA AND JOHNSTON METHOD : Add the width of mandibular incisors and divide by two. To the value add 10.5 to predict the combined widths of the mandibular cuspid and bicuspid and 11mm to predict the combined widths of the maxillary cuspids and bicuspids.

HIXON- OLDFATHER’S METHOD : The major problem with using radiographic method is evaluating the size of canine teeth. This method uses the size of permanent central incisors measured from the dental cast and size of the unerupted premolars measured from the radiographs to predict the size of the unerupted canines. A graph developed by Stanley-kerber allows canine width to be read directly from sum of incisor and premolar widths.

TWEED’S ANALYSIS : For any discrepancy in the occlusion, dental analysis have been used but Tweed mentioned that if teeth are not in a stable relationship with basal bone, relapse is liable to occur.So tweed introduced a face oriented analysis which took into account, not just the dental correction but cephalometric correction as well. This method incorporates the relationship of teeth to the basal bone.Also various mixed dentition analysis demonstrate the discrepancy only and do not indicate the exact area where the discrepancy occurs. In many instances, the problem is confined to a particular area and since it is possible to direct treatment specifically to one area , it is desirable to know the area affected

TWEED’S METHOD :Total discrepancy = dental discrepancy + cephalometric discrepancyDental arch discrepancy is calculated by the conventional method.Cephalometric discrepancy is assessed by Three planes are used for assessing jaw discrepancy. These are the Frankfort’s horizontal plane, mandibular plane and the lower incisal plane. Tweed established the following relationships: When FMPA is 21-29, then FMIA should be 68.

When FMPA is 30, then FMIA should be 65. When FMPA is 20 or less, then IMPA should not exceed 92.

So according to the guidelines, if FMPA is 30 and FMIA is 50 (which otherwise should be 65), an objective line making an FMIA of 65 is also drawn on cephalogram and distance between objective line and actual line is measured by callipers in mm. This is multiplied by 2 to include both right and left sides. This gives cephalometric discrepancy.

TOTAL SPACE ANALYSIS : It was developed by Merrifield and took into account the tooth measurement, cephalometric correction and soft tissue modification. This method also indicated the exact area ( anterior, posterior or middle ) where the space discrepancy occurred.

INTERPRETATION OF A MIXED DENTITION ARCH LENGTH ANALYSIS:

If an analysis predicts that a child will have no crowding problem, continue routine care and periodic observation of the patient.

When an analysis predicts borderline crowding (1mm - 4mm), maintain arch length with an appliance and periodically examine the patient. If a permanent first molar moved mesially because of premature loss of primary molar, use an appliance to regain the lost arch length before making a space maintainer. Prepare patients with borderline crowding for possible orthodontic treatment.

If an analysis predicts crowding in excess of 4mm, the patient will likely develop crowding of the permanent teeth that will require orthodontic treatment following a comprehensive evaluation of the malocclusion.

If crowding in excess of 6mm is predicted in the lower arch, the patient may benefit from the serial extraction treatment.

After space analysis it is necessary to identify the cases pertaining to space maintenance, space regaining , space supervision and gross discrepancy management.

GENERAL FACTORS AFFECTING SPACE MANAGEMENT

BIOLOGICAL FACTORS

Occlusal forces:: Primary teeth assume a 90 degree orientation of the occlusal plane, an upright arrangement probably responsible, atleast in part, for physiologic spacing commonly seen in the primary dentition exhibiting adequate arch dimension. Permanent teeth, however, maintain a mesial inclination during passive eruption .The resulting anterior component of force causes a physiologic mesial drift which may contribute to space closure, thereby establishing continuous arch.

Eruptive forces:: As the arches continue to develop & permanent molars erupt, a powerful mesial force is exerted. An intact dentition anterior to this force offers sufficient resistance; however if the arch continuity has been interrupted due to loss of either primary or permanent tooth, space closure is inevitable. The result is decrease in arch length. Eruptive force may be greater in the mandibular arch as the mesiolingual orientation of the erupting mandibular molar provides early contact, as well as continuous pressure against the last tooth in the arch. Maxillary mesial force may not be as significant. Distobuccal orientation of the erupting molar does not permit adjacent tooth contact until active eruption is nearly complete.

Muscular Forces:: Cheek, lip & tongue muscles may tend to limit labial, buccal & lingual movement of the teeth. These forces contribute to dental arch form by maintaining tooth contact & establishing relatively stable intermolar & intercanine width.

STAGE OF OCCLUSAL DEVELOPMENT: - More space loss is likely to occur if the tooth is actively erupting adjacent to the space left by premature loss of a primary tooth.

PERIAPICAL INFLAMMATION: - It may exert pressure on follicle contents & cause tooth displacement in various directions. Type of displacement is dependant on the direction, duration & amount of pressure exerted & can be classified into 3 categories.

Class1: movement around a center of resistance located in a vertical direction (rotation)

Class2: movement around a center of resistance located in a horizontal plane either in a mesiodistal or buccolingual direction (deflection)

Class3: 180 degree movement around a center of resistance located in a horizontal plane. (inversion)

Treatment in class 1 & class 2 involves extraction of offending primary tooth & space maintenance

Treatment in class 3 involves extraction of offending primary tooth & space maintenance & surgical intervention to reposition the tooth bud.

ANKYLOSIS: - Developmental problems associated with ankylosis include loss in arch dimension, occurring as adjacent teeth tip toward the depressed area in an attempt to maintain tooth contact. Prevention of normal exfoliation, possible results in ectopic or delayed eruption of permanent successor.

ACTIVE ERUPTION OF 1st PERMANENT MOLAR: - It extends over a considerable time period beginning as early as 4 ½ years of age in some instances & extending until the molars are in full occlusal contact at 6½ - 7 years of age. The maxillary permanent molar erupts distally & then swings forward to contact the 2nd deciduous molar.

If 2nd deciduous molar is missing early in the process & no space appliance is placed, it is common for the maxillary 1st permanent molar

crown to continue to swing mesially until it comes in contact with the 1st deciduous molar. There is complete loss of space & the 1st Permanent molar fully occupies the position of 2nd deciduous molar. As this occurs early in the eruptive process, much of the permanent molar root formation is still unfinished with completion taking place in this false position, with the result that the permanent molar develops in near normal upright position. If 2nd deciduous molar is extracted late in the eruption sequence of 1st permanent molar, than upper permanent molar will assume a more tipped position into the space & space closure is not severe

CARIES: - Dental caries continues as the single factor responsible for loss of arch circumference.By placing a stainless steel crown with too great a mesiodistal diameter, primate space between canine & molar is eliminated. This space may have permitted proper positioning of the permanent lateral incisor as it erupted, allowing distal & lateral repositioning of the primary canine. The result of treatment may well be crowding of lower incisor with possible midline deviation.

DIRECTION OF ERUPTION: - If space exists, direction of eruption of teeth is as follows. Molars erupt mesially, Premolars & canines erupt distally, Mandibular permanent incisor erupts mesially, guided into position by a tooth mesial to it. Maxillary permanent incisor erupts distally, guided into position by a tooth distal to it.

DENTAL ANOMALIES: - Fusion and Supernumerary teeth

ABNORMAL ORAL MUSCULATURE: - A strong mentalis muscle may damage the occlusion after the loss of a mandibular primary molar. A collapse of the lower dental arch and distal drifting of the anterior segment will result.

An abnormally high tongue position coupled with a strong mentalis and buccinator muscle may be damaging to the occlusion after the loss of a

mandibular primary molar. A collapse of the lower dental arch and distal drifting of anterior segment will be the result.

Local factors affecting space management

TIME ELAPSED SINCE LOSS: - If a tooth is scheduled for extraction, give a space maintainer. However, if a tooth is missing for 6 months or more, space loss needs to be evaluated for the decision.

EMERGENCE OF THE TOOTH: - Based on amount of root formation, (tooth will erupt when one half to three fourth of the root formation is complete but canine has slightly more root formation at the time of emergence). [Gron] Based on amount of bone covering the unerupted tooth, (A guideline for predicting emergence is that erupting premolars usually require 4-5 months to move through 1 mm of the bone as measured on a bite wing radiograph). If a primary molar is lost at 4 years of age, the emergence of the premolar is delayed by 1 year; emergence will occur at the stage of root completion. If primary molar is lost at 6 year, emergence will be delayed of 6 months; emergence will occur at a time when root development approaches completion.Several studies have indicated that the loss of primary molar before 7 years of age (chronological) will lead to delayed emergence of the succedaneous tooth, where as the loss after 7 years of age leads to an early emergence.

Eruption of succedaneous tooth (THE Fanning study): - An immediate spurt in the eruption of premolar has occurred regardless of the stage of development of premolar & timing of extraction of deciduous molar.

IN CASE OF EARLY EXTRACTION: - (4 yrs of age before completion of crown). The spurt is leveled off, the tooth remains stationery & erupted later than its antimere.

In case of LATE EXTRACTION: - (WHEN TOOTH IS ACTIVELY ERUPTING): - Due to this spurt eruption is fast & results in fast eruption.

Other instances where fast eruption occurs is when necrosis of bone occurs due to abscess or infection

SEQUENCE OF THE ERUPTION OF TEETH: - If the primary 1st molar has been lost prematurely & the permanent lateral incisor is in the active state of eruption, the eruption will result in a distal movement of the teeth. If first primary molar is lost during the time of eruption of the first permanent molar, a strong forward force will be exerted on the second primary molar which eventually tips into the space required for the eruption of the first premolar.

CONGENITAL ABSENCE OF THE PERMANENT TOOTH: - Partially impacted permanent teeth or deviation in the eruption path will result in abnormally delayed eruption.

DELAYED ERUPTION OF PERMANENT

In case of impacted permanent tooth,it is necessary to extract the primary tooth,construct a space maintainer & allow the permanent tooth to erupt at its normal position.If the permanent teeth in the same area of the opposing dentition have erupted,it is advisable to incorporate an occlusal stop in the appliance to prevent supraeruption in the opposing arch.

AMOUNT OF CROWDING

ARCH LENGTH ADEQUACY: - Before placing space maintainers or starting tooth movement, always evaluate the arch length

The position of the lower incisors over basal bone must be determined: - If the teeth are retroclined, one may obtain additional arch length by placing them in a more normal axial inclination. If the lower incisors are

near their upper limit when measured to the mandibular plane on a cephalogram, further flaring or anterior advancement would jeopardize the periodontal support of these teeth. The degree of crowding and amount of space needed to correctly align the anterior segment must be determined. Generally, every overlapped contact will require at least 1 mm or more of space for correction, depending on the severity of crowding.

CURVE OF SPEE: - According to (Andrews 1972), the ideal occlusion will have a nearly flat or very slight curve of Spee. When levelled, the teeth will require more linear space than they occupied before. 1 mm of linear space is required per side for every illimetre of the depth of the curve of Spee.

Abnormal Oral HabitsThey will exert abnormal pressure on dental arches and so may influence the type and planning of space maintainer.

Miscellaneous FactorsThese factors influence planning because they may be associated with either space gain or space loss. Some of these factors are growth of jaws, proximal caries,wear and attrition.

SPACE MAINTENANCE:

Space maintenance can be defined as “an appliance used for correct handling of space created by untimely loss of deciduous tooth, the absence of which lead to either malocclusion or encouragement of detrimental oral habits or to psychological trauma”. By J.C Braurer in 1941.Space maintenance or maintenance of arch perimeter is undertaken only when the following conditions are present:

1. Loss of one or more primary teeth.Effect of premature loss of primary teeth-

Space closure by drifting of teeth. Delayed or early eruption of succedaneous teeth. Tilting of tooth adjacent to extraction space. Creation of arch length inadequacy.

Encouragement of deleterious habits. Psychological trauma. Extrusion and rotation of opposing teeth. Unilateral tooth loss can lead to arch asymmetry and shifting of midline. Succedaneous teeth may become impacted due to bony crypt or

mucosal barrier. Development and aggravation of malocclusion.

2. No loss of arch perimeter.3. Favourable mixed dentition prediction.

The amount of space loss is associated with the length of time following premature extraction. The earlier the primary molars are extracted especially before the eruption of1st permanent molar, the greater are the chances of drifting of the adjacent teeth.

The highest prevalence & amount of space closure occurs after the premature loss of primary 2nd molar.

The rate of space loss is higher in maxillary than in mandibular premature extraction. The rate of space loss was age related mainly in the maxilla & not in the mandible. The mandibular space loss continued at a rather constant rate.

The loss in arch perimeter may occur due to caries or unwanted loss of teeth.

(A)Caries of primary teeth: This is one of the most frequent cause of arch perimeter loss in the mixed dentition. A carious lesion on the distal surface of the 2nd primary molar allows the 1st permanent molar to tip mesially. The first step in space maintenance is to preserve the size of the primary tooth crown by restoring the carious tooth as soon as possible.

(B) Loss of primary teeth :

When a primary tooth is lost , space maintainer is indicated when

1. The permanent successor is present and developing normally.

2. The space from the lost tooth has not diminished.3. Favourable mixed dentition analysis.

There is no reason to insert a space maintainer if the permanent successor is absent, nor should one maintain 4mm of space for a tooth known to be 7mm in width.

PRIMARY INCISORS :

There is controversy regarding whether space closure occurs in ant. region or not. Some believe space closure rarely occurs in the anterior part of the mouth. But this is not always true. Each case must be critically evaluated.

-If spacing is present, then little possibility of drifting of adjacent teeth will occur to cause the loss of space.

-But if no spacing or prior contact is present in the anterior region than there may be a collapse of the arch after the loss of one of the primary incisors is almost certain.

Even if spacing is present, it is desirable to replace missing incisor for acceptable esthetic, to prevent abnormal speech and tongue habits.

If the permanent successors have not developed sufficiently to maintain the dimensions of the arch , the loss of a primary incisor can result in the rapid closure of space. Space maintainer is not required if the primary tooth has been lost after the child is 4 years of age.

In children in whom space loss is likely to occur, an acid etch composite pontic not only serves as a space maintainer but aids esthetics as well.

PRIMARY CUSPIDS:

Other than caries , the eruption of large permanent incisor is the more frequent cause of the loss of primary cuspids.

Unilateral loss of a mandibular primary cuspid poses a special problem since the dental midline can be misplaced. The immediate extraction of the other primary cuspid should be considered and a lingual arch appliance should inserted to prevent the lingual tipping of the mandibular incisors and shortening of arch perimeter.

FIRST PRIMARY MOLAR :

In most cases the loss of 1st primary molar is not serious as the loss of the second primary molar. Arch perimeter loss is most likely to occur when the 1 st

primary molar is lost very early. The potential for space loss is greaterduring eruption of first permanent molars since this is the time when the permanent molar exerts a strong eruptive force against the distal crown surface of second deciduous molar. The maxillary first permanent molar usually erupts distally and begins a rotation to swing forward once the cusptips appear through the tissue at the eruption site.The permanent molar then contacts the second deciduous molar in a less direct eruptive force.However, at the time of contact, there should be a space maintainer in place to resist the potential for mesial displacement of second deciduous molar.

Space maintainers that can be used are removable plate or lingual arch or a band and loop. An alternative to band and loop is to attach a similar loop to the buccal and lingual surfaces of the 2nd primary molar with composite.

SECOND PRIMARY MOLAR :

According to Northway, Wainright & Demirjian Study

E loss had the most deleterious effect on dental arch length. Early posterior primary loss resulted in 2-4 mm space closure per quadrant in both arches. Space loss was age related in the upper but not in the lower arch. Upper D lost typically resulted in blocked out cuspids, upper E Loss usually led to an impacted 2 nd permanent premolar. The greatest space loss was caused by mesial molar movement. More space was lost in the 1st year after premature tooth loss than in successive years.

– The most rapid losses in the perimeter of the arch usually are due to a mesial tipping and rotation of the 1st permanent molar after removal of the 2nd primary molar. When this tooth is lost , always maintain space until the arrival of the second bicuspid.

– Maxillary permanent molar erupts distally and then swings forward to contact the second deciduous molar. If the latter is missing and no space appliance is placed, it is common for the maxillary first permanent molar crown to continue to swing mesially, until it come in contact with first molar thus blocking out the second premolar. The mandibular first permanent molar strongly depends on the presence of second deciduous molar distal crown surface for eruptive guidance. Thus if the deciduous tooth is lost during permanent molar eruption the latter will continue its mesial eruption pathway to produce a severe space loss and tipped position.

– Before inserting any appliance to maintain the 2nd primary molar space determine that no space has been lost. Never place a space maintainer when space regaining is indicated.

If the 1st permanent molar has erupted then a reverse crown and loop or band and loop or a similar loop held in place by composite is used to maintain space.

And if the 1st permanent molar has not yet erupted , then the free –end acrylic block type of maintainer may be used. The distal shoe space maintainer is not indicated because it is unhygienic and inflexible.

MULTIPLE LOSS OF PRIMARY TEETH :

Sometimes it is necessary to extract more than one primary tooth at the same appointment. In such cases it is best to insert the appliance the very day the teeth are removed. A lingual arch wire or a multiple acrylic space-maintainer will serve the purpose. It is not necessary to cast an elaborate framework and meticulously carve occlusal patterns for primary partial dentures. A block of acrylic to provide a smooth occluding surface , maintain the vertical height, and prevent extrusion of the opposite teeth will suffice.

CONTRAINDICATIONS OF SPACE MAINTAINER

There is no reason to place space maintainer if the permanent successor is absent

Do not place space maintainer to maintain 4 mm of space for a tooth known to be 7 mm in width.

FACTORS CONTRIBUTING FOR SPACE CLOSURE:

1. Inclination of long axis of permanent molars –tendency of molar to shift mesially because their long axis is mesially inclined.2. Premature loss of deciduous teeth3. Influence of buccal musculature – buccinator exerts forces that can derange occlusion.4. Path of least resistance- this is created following loss of support because of extraction or missing tooth.5. Effect of position of center of rotation of mandible– Smyd pointed out that more the axis of mandibular rotation is lowered in respect to occlusal plane, less is the amount of horizontal thrust transmitted to teeth in occlusion.

Space maintainers- ”are appliances used to maintain space or regain minor amounts of space lost, so as to guide the unerupted tooth into a proper position in the arch.”

IDEAL REQUIREMENTS

It should maintain the entire mesio-distal space created by a lost tooth.

It must restore the function as far as possible & prevent over-eruption of opposing teeth.

It should be simple in construction.

It should be strong enough to withstand the functional forces.

It should not exert excessive stress on adjoining teeth.

It must permit maintenance of oral hygiene.

It must not restrict normal growth & development and natural adjustments which take place during the transition from deciduous to permanent dentition.

It should not come in the way of other functions.

CLASSIFICATION OF SPACE MAINTAINER

CLASSIFICATION OF RFEMOVEABLE APPLIANCES BY BRAUER

Class1 – unilateral maxillary posterior

Class 2 – unilateral mand. posterior

Class 3 – bilateral max. posterior

Class 4 – bilateral mand. posterior

Class 5 – bilateral max. ant. & post.

Class 6 – bilateral mand. Ant. & post.

Class 7 – primary/ permanent anterior

Class 8 – complete primary teeth loss.

Removable space maintainers: - These are the space maintainers which can be removed and placed into the oral cavity by the patient. These are classified as functional and non functional. Acrylic partial dentures are given for multiple tooth loss. The clasps can be given on deciduous canines and molars for retention. Removable distal shoe space maintainer-an immediate acrylic partial denture with an acrylic distal shoe extension has been used successfully to guide the first permanent molar into position when the deciduous second molar is lost shortly before the eruption of the first permanent molar. The

According To Hinrichsen-

Fixed space maintainers-

CLASS I: - (a) Non-functional types

Bar type OR Loop type.

(b) Functional types

Pontic type OR Lingual arch type

CLASS II Cantilever type (distal shoe, band & loop.)

Removable space maintainers-

Acrylic partial dentures

According to Raymond C Thurow

Removable

Complete arch

Lingual arch

extra oral anchorage

Individual tooth

According to Hitchcock

Removable or fixed

With or without bands

Functional or non functional

Active or passive

Certain combinations of the above

tooth to be extracted is cut from the cast to allow fabrication of the acrylic extension. The extension can be removed after eruption of permanent molar.

Fixed Space Maintainers: - Space maintainers which are fixed or fitted onto the teeth are called fixed space maintainers.

ADVANTAGES:

1. Bands and crowns are used which require minimum or no tooth preparation.

2. They do not interfere with passive eruption of abutment teeth.

3. Jaw growth is not hampered.

4. The succedaneous permanent teeth are free to erupt into the oral cavity.

5. They can be used in un-co-operative patients.

6. Masticatory function is restored if pontics are placed.

• BAND & LOOP APPLIANCE (Fixed, Non functional, Passive space maintainer)

It is used to maintain the space of a single tooth. It is inexpensive & easy to fabricate. It does not restore the occlusal function of the missing tooth.

• LINGUAL ARCH (Fixed, Non functional, Passive Mandibular arch appliance)

It was popularized by Burstone. It is used to maintain the posterior space in the primary dentition. The lingual arch is often suggested when teeth are lost in both quadrants of the same arch. They belong to that group of space control appliances which not only control anteroposterior movements but also are capable of controlling & preventing an arch perimeter distortion, by controlling the lingual collapse of single tooth or segments of the arch. It consist of a round stainless steel or precious alloy wire,0.32 to 0.40 inches in diameter closely adapted to the lingual

surfaces of the teeth & anchored to bands on the first permanent molars. The means used to anchor the archwire to the bands will define whether the lingual arch is of a removable or fixed type. Because the permanent incisor tooth buds develop & erupt somewhat lingual to their primary precursors,a conventional mandibular lingual arch is not recommended in the primary dentition (bilateral band & loop appliances are recommended in this situation.)

PASSIVATION- The lingual archwire should be completely passive. This is done by heating the wire to a dull brownish appearance, while keeping the wire gently in place on the cingula with an old instrument. The maxillary lingual arch is feasible in the primary dentition because it can be constructed to rest away from the incisors.

Modifications 1. Hotz lingual arch – with U-loop used for space regaining

2. Removable lingual arch 3. Omega bends – in canine region to prevent interference.

Two types of lingual arch designs are used to maintain maxillary space- Nance arch (HN Nance, 1947) The Transpalatal arch (Robert Goshgarian, 1972).

These appliances use a large wire (36 mil) to connect the banded primary teeth on both sides of the arch that are distal to the extraction site. The difference b/w the two appliances amounts to where the wire is placed in the palate.The Nance arch incorporates an acrylic button that rests directly on the palatal rugae. The Transpalatal arch (TPA) is made from a wire that traverses the palate directly without touching it.

NANCE ARCH or NANCE SPACE HOLDING APPLIANCE (Fixed, Non-functional, Passive, Maxillary arch appliance): - Nance(1947) described the “preventive lingual wire”. It consists of bands on the upper molars,with the arch wire extending forward into the vault. The acrylic button is present on the slope of the palate & provides an excellent resistance against forward movement(U loop).The wire should extend from the lingual of bands to the deepest & most anterior point in the

middle of hard palate. ‘U’ bend is given in the wire for the retention of the acrylic 1-2mm away from the soft tissue.

• TRANSPALATAL ARCH (Fixed, Non-functional, Passive appliance): - The arch is soldered to both sides, straight without a button & without touching the palate. The basis of the appliance is that the migration & rotation is caused by rotation around the lingual root. By preventing this, space loss is prevented by the appliance. Cross arch anchorage can be used if only one of the primary molars is lost & both the permanent molars are erupted.

o DISTAL SHOE (Intra-alveolar, Eruption guidance appliance): - it is used to maintain the space of a primary second molar that has been lost before the eruption of the permanent first molar. An unerupted permanent first molar drifts mesially within the alveolar bone if the primary second molar is lost prematurely. The result of the mesial drift is loss of arch length & possible impaction of the second premolar.

DISADVANTAGES-

o Because of its cantilever design & the fact it is anchored on the occlusally convergent crown of the primary first molar, the appliance can replace only a single tooth & is somewhat fragile.

o No occlusal function is restored because of this lack of strength.

o Histologic examination shows that complete epithelialization does not occur after placement of the appliance.

o Other space maintainers

o SANNERUD’S SM (1955) –indicated when single tooth loss and abutment are present on both side.

o A coil spring of 0.7mm is placed on a soft SS wire of 0.25mm which is attached to two abutment teeth.

o INDIRECT SM – IN 1964 Jenning and Aronsons described a tech. for indirect fabrication of band and loop space maintainer.

o MAYNE SM- by W.R. Mayne is a non functional SM that permits minor adjustments for space control while the tooth in question is erupting.

DIRECT BONDED SM –it can be

anterior direct bonded functional SM

posterior direct bonded either

-functional when having pontic or

-non functional when only a arch wire

or Ni-Ti wire is bonded

GLASS FIBER REINFORCED COMPOSITE RESIN SM- it can as anterior esthetic functional SM or posterior functional SM

SPACE REGAINING

INDICATIONS: - Either one or more primary teeth have been lost or some space in the arch has been lost to mesial drift of the 1st Permanent molar or if mixed dentition analysis shows that if one could recapture what was once there, there would be adequate room for all the teeth.

MESIAL DRIFT OF PERMANENT MOLAR: - It involves 3 different kind of tooth movements: - -Mesial Crown Tipping - Rotation - Translation

There are distinct differences in the mode of mesial movement between the upper & lower 1st molar due to variation in crown shape, number of roots and occlusal relationship.

Maxillary 1st permanent molar quickly tips mesially with the loss of crown substance of primary 2nd molar. Mesial tipping causes the distobuccal cusp to become more prominent occlusally. Because of large lingual root of maxillary 1st permanent molar, rotation of crown also is seen with mesial tipping, the distobuccal cusp becoming more prominent buccally. When 2nd primary molar

is lost prior to eruption of 1st permanent molar, translation during eruption may be seen.

Mandibular 1st molars display mesial tipping, crown rotation and translation as well but more likely to show lingual tipping with mesial movement. The lingual tipping is caused by the absence of a lingual root & the fact that occlusal function occurs buccally to the centre of mass of lower molar aggravates the 1st

molars to drifts mesially

DISTAL MOVEMENT OF 1ST PERMANENT MOLAR: - The basic tooth movement necessary in space regaining is distal movement of 1st Permanent molar, which must recapitulate in reverse the movements that occurred as the teeth drifted mesially. Therefore, selection of space regaining appliance is dependant on whether tipping, translation, or combination of these movements is required. Surprising amount of arch perimeter space often is created just by distal tipping & rotation of the 1st molar. Therefore tipping & rotation should be achieved prior to attempting translation.

ANCHORAGE CONSIDERATIONS: - When appliances are used to reposition the first permanent molars, there is a reciprocal force exerted to the teeth and supporting tissues anterior to the space. The result may be an undesirable flaring of anterior teeth. Distal movement can be most satisfactorily achieved by headgear appliance.

Distalization potential for maxillary molars is 5-7 mm/side whereas the distalization potential for mandibular molars is 1-2 mm/side.

FIXED SPACE REGAINERS

Open coil space regainer: - Can be used to good advantage in mandibular arch when the first premolar has erupted into the oral cavity.Construction-

Molar band fitted to first permanent molar

Molar tubes spot welded in horizontal position both buccally and lingually

Impressions taken

Stainless steel wire bent into U shape

The base of U has a reverse bend to contact the distal surface of first premolar

A solder stop should be placed on both arms where the straight parts meet the bend in the wire.

A spaced coil spring is selected which will slide on the wire and is cut about 2-3 mm longer than the distance from the anterior stop to the molar tube.

The band is cemented with the springs compressed.

Gerber space maintainer: - When appliance has to fabricated directly in mouth during a relatively short appointment and requires no lab work.

Hotz lingual arch: - It is used when: -

Lower first permanent molar has drifted mesially, but premolar or cuspid has not drifted distally.

Evidence of sufficient space between first molar and developing second molar

Anchorage for movement is achieved as the arch contacts all the teeth. Besides, spurs can be added across the canines. After adjustment, the posts in the passive position should be approximately 1mm distal to their passive positions over the lumen of their tubes.

The arch is then forced forward and posts slipped into place. It is advantageous to use removable lingual arch space maintainer since it facilitates frequent removal of arch for the purpose of activation. Up to 4 mm of space can be regained in an effective and efficient manner. It can be used in cases where second molar is erupted

Lip bumper: - Easily used for space regaining procedures in which bilateral movement is desired

Construction- It consists of a heavy labial arch wire over which an acrylic flange is prepared in anterior region such that it does not contact the lower anteriors.

Instead it is used to relieve the lip pressure. The pressure can be used to distalize molars by incorporating loops in the arch wire just before it enters the buccal tube or utilizing the coil spring.

Anterior space regainer: -Labial tubes are directly bonded to lateral incisors. A 0.014” round wire is then inserted in an open coil spring and activated

REMOVABLE SPACE REGAINERS

Free end loop: -It utilizes a labial arch wire for stability and retention, with a back action loop spring constructed of 0.025 wire. The base of appliance is made of acrylic resin. Movement of the permanent molar is achieved by activating the free end of the wire loop at specific intervals of time.

Split saddle: - The functional part of the appliance consists of an acrylic block that is split bucco-lingually and joined by 0.025 wire in form of a buccal and a lingual loop. The appliance is activated by periodic spreading of the loops. The activator block is split with a disk after appliance has been processed.

Sling shot: -It consists of a wire elastic holder with hooks instead of wire spring that transmits a force against molar to be distalized. The distalizing force is produced by the elastic stretched on the middle of the lingual surface of the molar to be moved.

Removable space regainers with jack screw: -It incorporates an expansion screw in edentulous space. Space is opened by expanding the plates antero posteriorly.

SPACE SUPERVISION

It is done in cases, where it is doubtful by mixed dentition analysis whether there will be space for all teeth. The dentist clinically guides the eruption of the teeth and development of the occlusion.

PRINCIPLESIt should be begun only when the mandibular cuspid and premolar show at least one third to one fourth of root development. Primary teeth are extracted serially to allow normal eruotion sequence i.e 3,4,5 in the mandible and 4,3,5 in the maxilla. Efforts are made to make the mandibular teeth erupt before

maxillary teeth and care should be taken that a late mesial shift of the mandibular first permanent molar does not occur.

MESIAL STEP (class I) PROTOCOL :This protocol is used when there is a normal skeletal profile and the first permanent molar has already achieved a class I molar relationship at the time of instituting space supervision. STEP 1: Removal of the primary canine is begun when the mandibular permanent canine has clearly begun root formation. The purpose of this is to align the incisors and to make the canine erupt before the premolar. Several months after the primary canine has been removed, permanent canine can no longer erupt normally without moving into labioversion.STEP 2: Removal of primary 1st molar and slicing the mesial surface of the 2nd primary molar. This is to allow the canine to erupt distally and hasten the eruption of first premolar. After canine has arrived arrived in the arch, there usually is insuffient space for eruption of 1st premolar.STEP 3: A lingual arch wire is inserted and extraction of 2nd primary molar. This is to prevent the mesial drifting of the first permanent molar and to cause the second premolar to erupt before second permanent molar. FLUSH TERMINAL PLANE (END TO END) PROTOCOL :The protocol for space supervision with a flush terminal plane is quite similar to that for a mesial step – with one important exception. Since the molars are not in class I relationship and a late mesial shift cannot be allowed to occur, it is necessary to achieve class I molar relationship by guidance of the eruption of the maxillary first molar or its movement distally. STEP 1. Removal of mandibular primary cuspid and tipping of the maxillary 1st molar distally.STEP 2. Removal of primary 1st molar and slicing the mesial surface of the 2nd primary molar.STEP 3. A lingual arch wire is inserted and extraction of 2nd primary molar.

DISTAL STEP (CLASS II) PROTOCOL : In the mesial step protocol and flush terminal plane protocol the problem seen is in a balanced or nearly balanced facial skeleton. A space supervision problem

combined with a distal step is a much more serious problem and the space problem is quite secondary to the skeletal contributions to the class II.The basic skeletal dysplasia must be treated and the teeth positioned in the best way possible to accommodate after the skeletal correction is over.

GROSS DISCREPANCY PROBLEM

Gross discrepancy problems are those in which there is a great and significant difference between the size of all the permanent teeth and the space available for them within the alveolar arch perimeter. Gross discrepancy problem cannot be diagnosed until the early mixed dentition, as no clinically useful correlation has been shown to exist between the size of the primary teeth and those of the permanent dentition. Gross discrepancy problems are treated by serial extractions. Actually serial extraction therapy includes both the space supervision as well as gross discrepancy therapy. The difference between space supervision cases and gross discrepancy problem is largely one of strategy. In space supervision, the goal is to squeeze all permanent teeth into what obviously is minimal space. In the gross discrepancy problem , it is accepted at the start that insufficient space is available and therefore extraction of permanent teeth is ultimately necessary.As a general rule a dentist should not extract permanent teeth as a part of orthodontic therapy unless they have the technical skill to correct all the sequelae of those extractions, like the excess space left by the extraction of the teeth . So Eisner suggested few rules to prevent unwanted complications :Rule 1. There must be a class I molar relationship bilaterally.Rule 2. The facial skeleton must be balanced anterioposteriorly , vertically and mediolaterally.Rule3. The discrepancy must be at least 5mm in all the four quadrants.Rule 4. The dental midlines must coincide.Rule 5. There must be neither an open bite nor a deep bite.

The more a case deviates from these rules, the more difficult it will be to treat them.

REFERENCES

Graber TM. Principles and practice.2nd edition

Moyers RE. Handbook of Orthodontics.4th edition

McDonald RE. Dentistry for the child and adolescent.9th edition

Pinkham JR. Pediatric Dentistry. 4th edition

Stewart RE. Scientific foundations and clinical practice. 1988

Wei SY. Pediatric dentistry. Total patient care. 1988

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