1. MANAGING THE ARCH CIRCUMFERENCE
Diagnosis and Treatment Planning

2. Arch Circumference
The distance from the distal of the second primary molar (or mesial surface of the first permanent molar) on one side of the arch to that same surface on the opposite side of the arch.

3. Arch Circumference
It is the space which during the primary dentition is occupied by the 10 primary teeth, and the space that will be available for the eruption of the 10 succendaneous teeth.

4. Physiologic Forces
A tooth is maintained in its correct relationship by the action of several forces. An alteration in these forces can alter the relationship among the teeth.

8. The Problem of Pathologic Loss of Arch Circumference

9. Physiologic Forces
Of primary concern is the mesial migration of the first permanent molar; any mesial movement, by definition, reduces arch circumference.

11. Primary Causes of Loss of Arch Circumference
Extraction of posterior primary teeth due to pulpal pathology.
Interproximal caries

12. Premature Loss of Primary Tooth (Extraction)

16. Proximal Caries

18. Additional Causes of Loss of Arch Circumference
Ankylosis of primary tooth
Ectopic eruption of the first permanent molar

19. Anklyosis
Ankylosis
An aberration in the eruption of teeth in which the continuity of the periodontal ligament becomes compromised, with fusion of the cementum and bone at one or more locations. Results in the tooth being “submerged” relative to the occlusal plane. Adjacent teeth may tip into space, resulting in loss of arch circumference.

21. Ectopic Eruption Ectopic Eruption
Eruption of first permanent molar into the root of the second primary molar. Prevalence 2-3% Generally self-correcting, but can cause loss of second primary molar if not corrected, with first permanent molar positioning itself anteriorly, with resultant loss of arch circumference.

23. Ectopic Eruption of Lateral Incisor

24. TREATMENT ALTERNATIVES
In Managing the Arch Circumference

25. Four Alternatives MAINTAIN SPACE
By means of appliance therapy provide for the maintenance of the arch circumference present at the time of examination.
REGAIN SPACE
By means of active appliance therapy attempt to regain arch circumference (space) which was at one time available but has now been lost for whatever reason
CREATE SPACE
By a more sophisticated application of knowledge of the developing occlusion and/or by application of biomechanically active appliance therapy increase the amount of space available for the teeth as they erupt and possibly increase overall arch circumference.
ELIMINATE SPACE
Through extraction of permanent teeth with the subsequent closure of excess space, resolve sever discrepancies between tooth size and arch circumference.

26. For Space Management in the Primary Dentition
TREATMENT DECISIONS
For Space Management in the Primary Dentition

27. Treatment Planning Primary Dentition
Decision making regarding space management is not as challenging in the primary dentition as it becomes later in the mixed dentition.
This is due to a meager data base.
At this stage of development it is difficult to ascertain the existence of a tooth size/arch circumference discrepancy, and generally dento-skeletal malocclusions are not identifiable at this time.
Because of these diagnostic constraints, maintenance or preservation of the available space is accomplished should a primary tooth be lost prematurely.

28. Treatment Planning Primary Dentition
Three appliances are used to maintain the available arch circumference in the primary dentition:
Band and loop
Intra- alveolar or distal shoe
Removable acrylic appliance

29. Band and Loop Space Maintainer

30. Band and Loop
The band and loop is used to maintain space subsequent to the loss of the first primary molar.
The band is attached to the second primary molar and the loop extends to the distal of the primary canine.
This effectively reserves the space that is available for the eruption of the first premolar.

35. Intra-Alveolar (Distal Shoe)

36. Intra-Alveolar (Distal Shoe)
The intra-alveolar or distal shoe space maintainer is indicated following premature loss of the second primary molar and prior to the eruption of the first permanent molar.
The abutment tooth is the first primary molar with a wire extending distally to the mesial aspect of the unerupted molar and extending gingivally to contact the mesial surface of the permanent molar.
The gingival extension provides a surface along which the first permanent molar can erupt.
Subsequent to the eruption of the molar at age 6, an alternative appliance (lingual arch) must be placed.
Employment of a distal shoe dictates the employment of 2 appliances to maintain space until the eruption of the second premolar, at age

43. Removable Acrylic Space Maintainer

45. Removable Acrylic Appliance
A removable acrylic appliance is required should multiple posterior teeth be lost in one quadrant.
Extraction of both the first and second primary molars in one arch would prevent the utilization of either a band and loop or a distal shoe.

46. Removable Acrylic Appliance
Unless absolutely dictated by the circumstances, removable acrylic appliances should not be utilized for three reasons:
their success is too dependent on the child’s cooperation and compliance.
their ability to maintain the space for which they were designed is sometimes questionable,
children tend to break and/or lose them.

47. Treatment Planning Primary Dentition
In cases where there is bilateral loss of a single tooth it is preferable to fabricate and place two unilateral appliances than to place one bilateral one.
For example, a lingual arch placed on the second primary molars would interfere with the eruption of the permanent incisors.
Additionally, there is some growth in arch width with the eruption of the permanent incisors, and no appliance should be placed that would restrict this.

51. Fixed Anterior Esthetic Appliance

53. TREATMENT DECISION MAKING
For Managing Space Problems in the Mixed Dentition

54. Treatment Planning Mixed Dentition
Treatment decision making during the mixed dentition is more complex.
Primary dentition - basically a decision to maintain space
Mixed dentition - decision is to maintain, regain, create, or eliminate space.

55. BASIC PREREQUISITES FOR MANAGING ARCH CIRCUMFERENCE IN THE MIXED DENTITION
Profile is orthognathic
Relationship between the maxillary and mandibular dentitions is normal as evidenced by molar relationship, canine relationship, overbite, and overjet
This does not mean that the various management procedures to be discussed are not, or should not be utilized, only that absent the above prerequisites, there is likely an underlying malocclusion that simple management of the arch circumference in one plane of space one not resolve. Referral to a specialist competent to treat the case comprehensively is indicated.

56. Maintaining Arch Circumference (Mixed Dentition)
Appliances Utilized:
Mandibular Arch - Lingual Arch
Maxillary Arch - Palatal Arch

57. Lingual Arch

58. Lingual Arch

59. Nance (Palatal) Arch

60. Nance (Palatal) Arch

61. Maintaining Arch Circumference (Mixed Dentition)
The utilization of these “full arch” appliances emphasizes the concept of maintaining the integrity of the arch circumference rather than individual tooth spaces.
Single tooth appliances, such as a band and loop, are generally not appropriate in the mixed dentition due to the eruption sequence of teeth.
For example, a band and loop extending from the first permanent molar to the first primary molar would lose its anterior abutment, the first primary molar, prior to the eruption of the succedaneous tooth, the second premolar. The mesial component of force with the erupting second molar could force the first permanent molar forward reducing arch circumference and compromising the space for the second premolar.

62. Regaining Arch Circumference Mixed Dentition
Regaining arch circumference is not particularly complex and the prognosis is good.
The objective is simply to regain arch circumference that has been lost; for example, by distalizing first permanent molar(s) that have migrated mesially subsequent to the premature loss of posterior primary teeth.

66. Regaining Arch Circumference Mixed Dentition
Appliances used: Amount to be gained Mandible Maxilla
0-2 mm helical spring helical spring
loop lingual arch headgear
split saddle jackscrew
2-4 mm sling shot split saddle
split saddle headgear
lip bumper jackscrew

67. Loop Lingual Arch

68. Loop Lingual Arch

69. Head Gear

70. Jackscrew Appliance

71. Jackscrew Appliance

72. Helical Spring Appliance

73. Helical Spring Appliance

74. Slingshot Appliance

75. Split Saddle Appliance

77. Creating Arch Circumference Mixed Dentition
Typical appliance therapy might consist of using a headgear in the maxillary arch to distalize the first permanent molars, and a loop lingual arch in the mandibular to advance the incisors.
If the discrepancy is small, 1-2 mm, it may be possible to provide additional space in the anterior region to permit favorable alignment of the permanent incisors by selective stripping of the primary canines and/or sequential extraction without employing active appliance therapy. The option for ‘creating space’ in this manner is due to the existence of the leeway space; essentially borrowing space from the posterior for the anterior. Another way of saying it is using the leeway space to overcome incisor liability.

78. Leeway Space
Nota Bene
Remember that the majority of the leeway space is ‘housed’ in the primary second molar/second premolar differential.

82. Creating Arch Circumference Mixed Dentition
Typical space creation protocol:
Removal of primary canines to allow for the alignment of the permanent incisors. One of the incisors may have been lost due to ectopic eruption of the lateral inciosr. Should this have occurred, extraction of the contra-lateral canine should be accomplished to preserve the midlines.
Placement of a lingual arch. Failure to place a lingual arch will result in the incisors positioning themselves lingually. This will close the canine space and shorten the arch circumference.
Removal of first primary molar and stripping of mesial surface of second primary molar. This is accomplished when it appears the canine cannot erupt normally; thus allowing the canine to erupt distally.
Removal of second primary molar when the first premolar is erupting to allow room for its eruption.
Removal of the lingual arch after eruption of the second premolar.

83. Lingual Arch