1. Space maintainer

2. Contents : Definition . Requirements of S.M.
Factors affecting S.M. Construction or indications of S.M.
Contraindications.
Mixed dentition analysis.

3. Definition :
-Space maintainer:
is the process of maintaining the space previously occupied by a tooth, several teeth or tooth structure before the eruption of the permanent tooth or construction of fixed appliance.
S.M is a device used to maintain space created by premature loss of primary tooth or teeth till eruption of permanent successor or to maintain space created by extraction of permanent tooth or teeth till construction of fixed replacement at age of 18.

4. Requirement of space maintainers:-
Simple design permitting easy construction and placement.
Hygienic so that caries susceptibility is not increased.
Durable, corrosion resistance, easily adjustable, and require minimal supervision.
Must not interfere with normal growth pattern.
Doesn't interfere with normal eruption of permanent teeth.
Reasonable in cost and in time required for fabrication.

5. Contraindications: Requirements (continuous) :
Maintain M.D and vertical dimension of space.
Esthetically accepted especially for anterior.
Restore function of mastication and phonetics.
Contraindications:
Sufficient space for eruption.
Sever crowding, as orthodontics intervention will need for certain.
Permanent near to eruption
Already space lost.

6. Causes of space loss: Early loss of deciduous tooth. Ankylosis.
Caries and faulty restoration.
Congenital missing teeth.

7. Factors affecting S.M construction OR indication of S.M:
Time elapsed since loss of teeth.
Dental age of the patient.
Amount of bone covering the uneruptrd tooth.
Sequence of eruption.
Delayed eruption of permanent teeth.
Congenital absence of permanent teeth.
Degree of development of permanent teeth.
Factor related to arch length adequacy.

8. 1-Time elapsed since loss:-
-If space closure occurs, it usually takes place during the first 6 months after the extraction. So S.M is best to insert to construct as soon as possible after extraction.
-If space lost we need to construct an active space maintainer (space regainer) to regain the lost space before the eruption of the permanent successor.

9. 2- Dental age of the patient:
The chronologic age of the patient is not important as the developmental age. So we must depended on the developmental age to decide whether to construct a spac maintainer or not.
Studies have showed that teeth erupted when three fourth of the root is developed regardless of the child's chronologic age.

10. 3-Amount of bone covering the unerupted tooth:
Prediction of tooth emergence based on root development and the influence of the time of the primary tooth loss are not reliable if the bone covering the developing permanent tooth has been destroyed by infection.
In such case the emergence of the permanent tooth is usually accelerated regardless time, root development and age.

11. If there is bone covering the crowns, it can be readily predicted that eruption will not occur for many months; S.M is indicated.
Studies showed that tooth need 4-5 month to move 1 mm through the bone as measured on a bite-wing radiograph.

12. 4- Sequence of eruption:
-We should observe the relationship between developing and erupting teeth adjacent to the space created by premature loss of primary teeth.
-Premature extraction of lower D →during active eruption of lower 2 →make pressure on lower C→ distilization→ encroach on space of lower 4 lead to:-
1-Midline shift
2-loss of space
3-Increase overjet due to lingual inclination of lower 1,2

13. 4-Lower 4 fall to erupt or deviated.
If lower E is premature extract and lower 7 is a head of lower 5 in eruption→ lower 7 will make pressure on lower 6→ mesial drifting on space of lower 5→ space loss.
Lower D premature extraction→ during active eruption of lower 6 lower 6→ make pressure on lower E and encroach on space of lower 4.

14. 5-Delayed eruption of the permanent tooth:
Sometimes individual permanent tooth is often observed to be delayed in their development and in their eruption. In these cases, it is necessary to extract the primary tooth, construct a space maintainer, and allow the permanent tooth to erupt and assume it is normal position.
6-congenital absence of the permanent tooth:
If the permanent tooth is congenital missing:-
-Try to preserve primary tooth.
-If not restorable, extract and maintain space till age 18 to construct fixed prosthesis.

15. 7-Degree of development of permanent successor
-The developing un erupted tooth doesn't move in its crypt till the complete calcification of the crown and the beginning of root formation.
-At the time of extraction if crown is incomplete formed and calcified, this allow healing of the socket by bone and delayed eruption so construct S.M.

16. 8-factors related to arch-length adequacy
- Before constructing a S.M or start tooth movement the dentist should evaluate arch length.
- This evaluation is quite important during primary and mixed dentition.
- Regardless of the method used for (ALA) several factors should be considered:
1- Development of dental arches and occlusion.
2- Establishment of functional occlusion.
Determine size of permanents teeth that are yet to erupt especially mesial to 6 by x-ray, prediction chart or both.

17. Classification of space maintainers
1-According to mean of retentions:
A)Removable
1-Partial Denture
2-Complete Denture
3-spoon denture
b)Fixed
1-Band&Loop.
2-St.st crown &loop
3-distal shoe
4-passive lingual arch
5-modified fixed PD
6-transpalataal arch
7-Nance holding arch

18. According to activity:
c)Semi-fixed (space regainers)
1-active lingual arch
2-active transpalatal arch
3-coil spring
4-head gear
According to activity:
a)Active S.M
1-Active lingual arch
4-finger spring (midline screw)
b)Passive S.M
All the rest

19. According to function: A)Functional
1-CD
2-PD
3-Soon D
4-Modified fixed PD
b)Non-functional
All the rest
Note: S.M can be classified in various way
1-removable or fixed or semi-fixed
2-with band or without
3-Bilateral loss

20. Band and loop space maintainer:
The most common S.M used.
It is a unilateral space maintainer.
Indicated for S.M in posterior segment.
It has a simple cantilever design.
The loop has limited strength so:
The appliance must be restricted to holding space for one tooth
It is not expected to accept functional force of chewing.
The loop must be wide faciolingually to allow eruption of permanent molar without its removal

21. The loop should be in close approximation to the ridge without impinging on soft tissue.
It should not restrict any physiologic movement or adjustment of adjacent teeth.
Occlusal rest is an optional addition to the loop portion of the appliance when it is used in the posterior segment, this prevent gingival tipping of the appliance and the abutment tooth which can result in gingival irritation and space loss.

22. Advantage:- Disadvantage: Easy and economical to make.
Takes little chair time.
Adjusts easily to accommodate the changing dentition.
Disadvantage:
Does not restore chewing function.
Will not prevent the continued eruption of the opposing teeth.
One tooth only.
Limited strength.
Cement dissolution lead to caries.
Irritation gingival tissue.
Not esthetic.

23. Steps of construction:
Selection of an orthodontic band that fits the tooth (usually the tooth distal to the space). Adapt the band well on the tooth by means of a band pusher.
An alginate impression is made of the abutment tooth including the area of the premature lost tooth and the primary canine
The band should be removed from the tooth and replaced securely in the alginate impression.
Stone is poured into the impression to produce a working model.

24. A loop of 0.7 mm st.st wire is contoured to rest on the tissue and contact the distal surface of the primary canine at the gingival area. The loop should be sufficiently wide to allow for eruption of the premolar.
The loop is soldered to the band on the stone model. The space maintainer is removed, polished, and prepared for cementation in the mouth.

25. Chrome-steel crown and loop:
It is used in posterior abutment tooth when:
Tooth has extensive caries and requires a crown restoration.
When the abutment tooth has had vital pulp therapy, so it is desirable to protect the crown with full coverage.
The loop is cut off crown is soften and smoothing abutment when there is no need for loop anymore.

26. Advantage: Easy and economical to make. Take little chair time.
Disadvantage:
Because it is difficult to remove the crown to make adjustments in the loop, some dentist prefer to adapt a band over a cemented crown and construct a conventional band and loop appliance.

27. Transpalatal arch: It is a bilateral fixed space maintainer
It is used in the upper arch only.
Used when bilateral loss of the D and multiple loss of primary molars.
Ideally, the appliance should formed so that it lies passive in the molar sheaths and contoured to the palatal tissue to maintain a distance of about 2 mm from the mucosa . This will allow optimal comfort without impingement into the palatal mucosa.

28. Lingual arch:
It is used when we have bilateral loss of the first primary molars and multiple loss of primary molars in the lower arch if the lower permanent incisors are erupted
In case where we still have lower primary incisors, a bilateral band and loop space maintainer is indicated.
The wire should closely adapt to the cingulum areas of the incisor and lingual surfaces of the posterior teeth, and attach it to bands on either the first permanent molars or the primary second molars.

29. There are two general types of lingual arch:
Fixed: which is fabricated by soldering the arch wire to the bands.
Fixed- removable: in which the ends of the arch wire are fitted into tubes attached to the lingual surfaces of the molar bands.

30. Maxillary lingual arch:
It is attached to bands on the DE of 6 contacting the cingulae of max. incisors.
Used when overbite is not excessive, if overbite is excessive so it is preferable to use transpalatal arch or Nance holding arch or RPD.
It rests on the cingulae of the incisors, approximately 1:1.5 mm off the soft tissue, stepped to the lingual in the C region to remain away from the primary molar and unerupted premolars.

31. Nance holding arch:
It is a fixed bilateral space maintainer, used in the upper arch if there is bilateral loss of first primary molar and multiple losses of primary molars.
It is similar to the lingual arch except the ant. Portion of the arch does not touch the lingual surfaces of the upper ant. Teeth. Instead, the arch wire is contoured against the slope of the ant. portion of the palate approximately 1 cm distal to the lingual surfaces of the central incisors to help retain the cured acrylic (acrylic button).

32. The distal shoe appliance:
Disadvantage:
Unhygienic
Tissue irritations and inflammation in the area of the acrylic button
The distal shoe appliance:
It used before eruption of 6 with missing E and using D as abutment, to guide 6 to erupt in a normal position such as crown or band maintainer with shoe extension or distal intragingivel extension .

33. Steps of construction:
Indications:
Unilateral loss of E before eruption of 6 and with presence of D
Good oral hygiene
Pt. cooperative
Physical condition good
Steps of construction:
Crown for D. St. st crown provides a desirable retentive contour for the placement of st.st band, although a well-adapted band on a non-crowned tooth may be satisfactory
The band is placed over the crown on the abutment tooth.

34. An alginate impression is made, the band is removed and placed in the impression, and a stone model is prepared.
If the E has not yet been removed it is cut off the model. A hole that stimulates the position of the distal root of the tooth is made by a bur in the model.
If the E has been removed previously, the positioning of the tissue extension may be determined with dividers and a bit-wing radiograph.
The tissue –bearing loop is contoured with a wire extending distally and into prepared opening on the model. The free ends of the loop are soldered to the band.

35. The band and loop appliance is removed from the model and the V of the tissue extension is filled in and soldered with pieces of 0.04 inch wire.
The appliance consists of metal or plastic guide plane along with permanent molar erupts.
If the E has previously been extracted and the extraction site has healed, a knife-edge is formed at the apex of the V, it will be forced through the anesthetized area of the ridge.
If it is delivered at the time of extraction, the intra gingival extension is just polished but not sharpened

36. Note: before final placement of the maintainer in the mouth, a radiograph of the appliance should be made to determine whether the tissue extension is in proper relationship with the un erupted 6. Any final adjustment in length and contour of the shoe may be made at that time.

37. Points to be in mind during construction of distal shoe:
It is not necessary to have the distal extension in direct contact with 6 unless the tooth has already moved mesially.
The depth of the intra gingival extension should be about 1.0 to 1.5 mm below the mesial marginal ridge of the molar, or just sufficient to capture its mesial surface as the tooth erupts and moves forward.
After the molar has erupted, the intragingival extension is removed.
If the appliance is to be used as a reverse band and loop space maintainer, it may be necessary to add a supragingival extension to prevent the molar from tipping over the wire.

38. Contraindications:
Several teeth are missing; there may be lack of abutments to support a cemented appliance.
Poor oral hygiene.
Lack of patient and parental cooperation.
Certain medical condition such as blood dyscrasias, immunosuppression, congenital heart defects, history of rheumatic fever diabetes or generalized debilitation

39. Disadvantage: No Occlusal function is restored
Lack of complete epithelialization around extension.
Not esthetic, can't prevent over eruption of opposing

40. Unilateral Loss of DE the distal shoe appliance can be constructed using the contra lateral E and both C connected by lingual arch.
Bilateral loss of four DE are lost prior to eruption of 6, use bilateral distal shoe extension utilizing primary canine abutments .
All distal shoe space maintainers are temporary and should be substituted by a lingual holding arch or removable space maintainer following 6 eruptions.

41. In situations in which the distal shoe is contraindicated, two possibilities for treatment exist:
Allow the tooth erupt and regain space later.
Use a removable or fixed appliance that does not penetrate the tissue but places pressure on the ridge mesial to the unerupted permanent molar.

42. Removable PD:
The most useful space maintainer used for bilateral posterior space maintenance when more than one tooth has been lost in posterior segment and still permanent incisors have not yet erupted.
We can't use in this case:
Band and loop because of the length of the edentulous space.
Lingual arch because of lingual position of the unerupted permanent incisors .

43. 1-Replacing Occlusal function. 2-Esthetic appearance.
Advantage: (RPD)
1-Replacing Occlusal function.
2-Esthetic appearance.
3-Prevent abnormal speech and tongue habits.
4-Can be readily adjusted to allow for the eruption of teeth.
5-Simplicity of construction.
6-Of little cost to the patient.
Disadvantage:
1-Needs patient cooperation:
- If failure to wear ,it lead to space loss.
- If failure to remove, it leads to soft tissue irritation.
2- Breakage of the appliance.

44. Modified fixed PD:
The bands will be adapted on the last molars in the arch.
The arch wire will be adapted on the bands touching the lingual surfaces of the edentulous area.
Acrylic base will be applied to engulf the wire.
 Spoon denture:
Is a removable appliance
Usually it is used to replace a single tooth lost in the anterior region
It has no clasps
Depends on the vault of the palate in its retention

45. Full denture in children:
It is indicated in children with loss of all primary teeth due to:
Wide spread of oral infection
Teeth are extensively decayed and are unrestorable
Complete anodontia. 
Advantage:
Improved esthetics
Restore function
Important in guiding the first permanent molars into their correct position

46. Failure of space maintainer
Causes of failure:
Loss of cement
Solder failure both may be due to mechanical stress in lone term use rather than appliance design
Soft tissue lesion (occure with unilateral more than bilateral)
Interference with eruption as lingual arch during eruption of permanent incisors

47. Breakage (occure with bilateral more unilateral)
Distortion
Design problems
Deterioration of fit
Lost tooth from denture
Improper selection
Poor patient cooperation and poor esthetic

48. Things to be remembered:
1- If band too wide use thick mix to increase fixation
2- If band too small, must be properly seated to avoid gingival inflammation
3- Seating of the S.M must be 1 mm easily seated under finger pressure or band setter, band pusher or burnisher , no bite on it to avoid voids.
4- Band selection may be read made or custom made for better fitting using rubber base as impression material as show less dimensional changes and no voids.

49. 5- Loop must be: parallel to the space, 1 mm above gingival just below contact of patient, no harm for tongue or cheek
6- Selection of cement. Cement failure:
a- failure under mechanical force, brittle cement
b- Increase solubility
7- Excess of cement removed to avoid pocket and high spot
8- Types:
a- Znph or polycarboxilate: 40% failure rate
b- GI: more adhesive & fluoride release
9- Follow up every one year remove and recommended fluoride application to decrease caries on bonded tooth

50. THANK YOU FOR YOUR ATTENTION…..