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 Table of Contents  
REVIEW ARTICLE
Year : 2015  |  Volume : 6  |  Issue : 1  |  Page : 22-28

Orthodontic challenges in mixed dentition


1 Department of Orthodontics, KAPV Govt Medical College, Trichy, India
2 Vinayaka Mission's Sankarachariyar Dental College, Ariyanoor, Salem, India
3 Department of Orthodontics, JKK Nataraja Dental College, Komarapalayam, Tamil Nadu, India

Date of Web Publication19-Jan-2015

Correspondence Address:
Diravidamani Kamatchi
135 C, Madurai Road, Manaparai - 621 306, Trichy, Tamil Nadu
India
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DOI: 10.4103/0976-433X.149585

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  Abstract 

Orthodontic intervention in the mixed dentition does not always prevent orthodontic treatment in the permanent dentition; however, there can be significant advantages to early intervention. Identifying certain problems at an early age offers a possibility either to redirect skeletal growth or to improve the occlusal relationship. The primary objective of managing orthodontic problems in the mixed dentition stage is to intercept or correct malocclusions that would otherwise become progressively more complex in the permanent dentition or result in skeletal anomalies. The purpose of this article is to discuss how to identify and treat such common situations and malocclusions in the mixed dentition that lend themselves to early intervention

Keywords: Arch expansion, 2 × 4 appliance, early orthodontic treatment, growth modification, mixed dentition, skeletal malocclusions


How to cite this article:
Kamatchi D, Vasanthan P, Kumar SS. Orthodontic challenges in mixed dentition. SRM J Res Dent Sci 2015;6:22-8

How to cite this URL:
Kamatchi D, Vasanthan P, Kumar SS. Orthodontic challenges in mixed dentition. SRM J Res Dent Sci [serial online] 2015 [cited 2019 Sep 20];6:22-8. Available from: http://www.srmjrds.in/text.asp?2015/6/1/22/149585


  Introduction Top


Most orthodontic patients are treated in the early permanent dentition, generally at 12 ± 13 years old when the second molars erupt. However, it is important to make an annual assessment in the mixed dentition to identify developing problems and where necessary arrange treatment. It has been found that comments made about teeth were more hurtful in the 9-10 year age group. [1]

The American association of orthodontists recommends that every child have an orthodontic examination by the age of seven. By then, the maxillary and mandibular first molars, lateral incisors and central incisors should have erupted.

Early intervention can simplify or eliminate the need for later treatment. Mixed dentition treatment is an important subject because early treatment could not only correct the occlusion, but also may ensure normal development of the teeth and jaws. One of the main advantages of early treatment is the majority of malocclusions can be corrected without extraction of permanent teeth and non-surgically.

The benefits of early treatment

For those patients who have clear indications for early intervention, early treatment presents the opportunity to:

  • Influence jaw growth in a positive manner
  • Harmonize width of the dental arches
  • Lower risk of trauma to protruded upper incisors
  • Improve airway/speech problems
  • Correct harmful oral habits
  • Preserve/gain space for erupting permanent teeth
  • Improve eruption patterns-less likelihood of impacted permanent teeth
  • Improve aesthetics and self-esteem
  • Simplify and/or shorten treatment time for later corrective orthodontics.


Patient assessment

Case history taking in these children should include parental and patient concerns, any relevant history of trauma and early loss of teeth, digit sucking or musical instrument play.

Clinical evaluation

The greater challenge lies in a precise diagnosis, which demands an exacting study with proper judgment and experience if improper treatment is to be avoided. Differentiation must be made between those cases that need immediate attention and those that should be postponed for comprehensive treatment during the post-pubertal growth spurt. The most common conditions to look for in the mixed dentition include premature loss/over retained deciduous teeth, submerging molars, supernumerary teeth, midline diastema, first permanent molars of poor prognosis, cross-bites (posterior/anterior), excessive protrusions, anterior/posterior open bites, ectopic eruptions, severe arch length discrepancies, patients with functional shifts of mandible and cleft palate.

Study models

Study models are necessary because they allow evaluation of the occlusion outside of the patient's mouth. For example, abnormal wear patterns and cross bites can easily be seen. Study models also allow the clinician to perform a mixed dentition analysis. Many mixed dentition analyses exist, such as the Tanaka and Johnston and Moyer's prediction values. An accurate bite registration must also be taken as part of this record.

Radiographic assessment

Orthopantomograph


An orthopantomogram is a useful screening radiograph for a preliminary assessment [Figure 1]. In the mixed dentition phase, it enables visualization of permanent erupting teeth, crowding of teeth, space or lack of space between teeth, eruption paths, third molars, supernumerary teeth and root apex formation, (which is used to determine the patient's dental age). In addition, a standard occlusal view or periapical radiograph may be needed if there is a history of trauma, missing teeth [Figure 2] or where the presence of supernumeraries may be suspected.
Figure 1: An orthopantomogram of mixed dentition period showing early loss of lower canines (arrows) - indication for serial extraction

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Figure 2: Intraoral periapical to evaluate delayed eruption of central incisor

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Cephalometric radiograph

Lateral head films are necessary when evaluating growing children to evaluate dentofacial proportions. The relationship between the teeth and the underlying growing skeletal bases is only visible with a cephalometric film and the appropriate cephalometric tracing. Patients with Class II or Class III molar relationship, significant variation in normal overjet and overbite and changes in skeletal or soft-tissue pattern are candidates for cephalometric analysis even in mixed dentition.

Treatment summary

The above evaluation helps to collate thoughts on the main features of the malocclusion and will help with treatment planning, e.g., 10-year-old boy with a developing Class II Div I, OJ 7 mm already with trauma to upper right central incisor-"possible candidate for early advice and treatment." The timing of orthodontic intervention is crucial, which depends on the type of malocclusion being treated [21] [Table 1].
Table 1: Utility of early treatment protocols according to the type of malocclusion

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Treatment plan (options)

  • Observation.
  • Preventive procedures.
  • Guidance of eruption and other interceptive procedures.
  • Proceed with active treatment, e.g., removable appliance/fixed appliance.


Treatment option 1: Observation

At an early age, a more conservative approach is to first place these children under periodic observation to determine the future developmental trend. Self-correcting anomalies are transient malocclusions present during the normal development of dentition and occlusion. They do not need any corrective measures, but get corrected themselves as they pass through the developmental stages.

Most of the parents will bring their kids at the age of 9 or 10 complaining about anterior spacing Ex-(a) Generalized spacing in deciduous dentition. (b) "Ugly duckling stage"-it occurs owing to eruption process of canine, once canine is erupted the diastema will close by itself [Figure 3].
Figure 3: Maxillary diastema at 11 years of age-Transient malocclusion

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Always palpate for permanent maxillary canines in the labial sulcus at the age of 9 ± 10 years. If a bulge is present in the buccal vestibule, it is more likely that the canines erupt into a normal position. If a buccal bulge is not present, there are higher chances of palatal impaction at a later date and hence requires further investigations and periodic reevaluation.

In cases with severe true skeletal mandibular prognathism, the limited success of early intervention is a reality and must be recognized. In such a child with severe prognathism, no treatment until orthognathic surgery can be performed at the end of the growth period is the best treatment. [2]

Treatment option 2: Preventive procedures

Space maintainers


It is essential that children be evaluated for missing primary teeth in order to determine if any space maintenance is necessary. As a general rule of thumb, it is recommended that all space created by a missing primary tooth should be maintained if root development of succedaneous tooth is less than 2/3 rd of total root length. [3] If there is an early loss of a primary molar and the first permanent molar is allowed to drift mesially, it will end up in the loss of the Leeway space and potentially interferes with the eruption of the premolars or canines. Lingual holding arch/Nance palatal arch placed before extraction of primary molars effectively preserves the leeway space [Figure 4]a and b.
Figure 4: (a) Unilateral space maintainer (b) Lingual arch

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Treatment option 3: Interceptive procedures

Serial extraction


This procedure refers to planned and sequential extraction of certain teeth undertaken to intercept a developing arch length deficiency. The procedure is instituted when patient is about 8 years of age. Serial extraction should be carried out cautiously after evaluating skeletal pattern, root development and space requirements. Serial extraction is strictly contraindicated in cases with Class II or Class III skeletal pattern and in oligodontia. [4] Cases successfully treated with serial extraction include tooth size arch length discrepancy (TSALD) where intra alveolar growth is not sufficient and skeletal Class I malocclusions with severe crowding.

The most frequently involved procedure is extraction of all "C"s to allow alignment of incisors, followed by extraction of D's to hasten eruption of permanent I premolars followed by extraction of all four I premolars to allow permanent canine eruption. However, the extraction pattern can be modified according to the individual case requirements. Careful radiographic evaluation prior to extractions is strictly indicated to assess root development of permanent teeth and prevent canine impaction.

Interception of habits

Thumb sucking, digital habits, anterior and lateral tongue thrusts, airway problems including mouth breathing and jaw joint temporomandibular joint problems must be corrected early. Habit breaking appliances can be both fixed and removable. Fixed appliances use two bands cemented on either the permanent first molars or the primary second molars [Figure 5]a. Removable appliances need to be worn all the time, even when eating to bring about adequate results. With digit habits, the bonded appliance alters the way the finger feels when inserted in the mouth. The bluegrass roller is an excellent appliance for eliminating digit habits [Figure 5]b. After successfully wearing a tongue or digit habit appliance and eliminating the abnormal tooth moving forces, the natural forces from the muscles in the cheeks and lips will correct the protrusion in most cases.
Figure 5: (a) Tongue spikes-fixed (b) Bluegrass roller appliance

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Intervention with surgical procedures

Maxillary labial frenectomy should only be performed after it has been shown that the frenum is a causative factor in maintaining a diastema between the maxillary central incisors. This cannot be determined until after the permanent canines have erupted. Therefore, a maxillary labial frenectomy prior to the age of 11 or 12 is probably not indicated and should be avoided. [5] A child may need to get a frenectomy earlier if the labial frenum is pulling on the gums causing them to recede, causes the child pain or makes it difficult for the child to eat or speak [Figure 6].
Figure 6: Indication for early maxillary frenectomy-Trauma to frenum

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Other minor surgeries include operculectomies to remove fibrous obstruction of erupting tooth bud, removal of retained deciduous teeth, supernumerary teeth and elimination of any bony obstruction for tooth eruption.

Treatment option 4: Active orthopedic/orthodontic treatment

Since 90% of the face is developed by age 12, early intervention is a must if one wants to guide and modify the growth of younger patients. Most recent emphasis is on functional-orthopedic philosophy favoring a two Phase orthodontic treatment. Phase I or interceptive treatment usually starts about age 7-9, when the child has most primary teeth and a few permanent teeth (incisors and I molars). The goal of Phase I treatment is to correct moderate or severe orthodontic problems including skeletal discrepancies, cross bites and severe crowding. Phase I treatment takes advantage of the early growth spurt and turns a difficult orthodontic problem into a more manageable one. This often helps to reduce the need for extraction or surgery and delivers better long-term stability. Most Phase I patients require a second Phase of treatment in order to achieve an ideal final bite.

Phase II treatment usually occurs after the remaining permanent teeth erupt, including second molars. This most commonly occurs at the age of 12 or 13. The goal of Phase II treatment is to achieve an ideal bite with all of the permanent teeth. Dental problems are solved with fixed appliances in the permanent dentition. The University of the Pacific's orthodontic department has conducted a research project with early orthodontic treatment. The study involved patients who received an initial Phase of treatment between the ages of 8 and 10. Patients who received Phase I early treatment had fewer visits, shorter treatment times and significantly lower orthodontic fees than those who required full-banded orthodontic treatment. [6]

Growth modification procedures

Skeletal problems such as constricted dental arches and protrusive/retrusive jaw bones are best treated as early as possible with functional appliances in the mixed dentition period of growth. One of the main advantages of early treatment is the majority of malocclusions can be corrected without extraction of permanent teeth and non-surgically.

Correction of sagittal problems

Skeletal Class II malocclusion


Baccetti et al. [7] have shown that all Class II features in the primary dentition are maintained or worsen during the transition to mixed dentition and the vast majority of treatment decisions are made in the mixed and early permanent dentition. McNamara and Brudon and Moyers et al. [8] made a revelation that 80% of Class II malocclusions have retrognathic mandible. Apart from the genetic etiology, the most important factor in the treatment of Class II Div I malocclusion is the proper maxillary arch form which will encourage normal function.

If the problem is flared anteriors with a slight increase in overjet, arch expansion with Schwarz appliance along with a labial bow would normalize the incisor position and reestablish normal function. [9] The next step will be the use of functional appliances, which reposition the jaws, allow eruption of posterior teeth and effectively move the condyles to a more physiological position. Various appliances like twin block [Figure 7]a, Rick-A-Nator [Figure 7]b effectively correct retruded mandibular position. [10]
Figure 7: Growth modification procedures for skeletal class II malocclusion, (a) Twinblock appliance, (b) Rick-A-Nator, (c) High pull headgear

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In cases with true maxillary prognathism, regular use of headgear [Figure 7]c produces desired effect. Growth hormone release occurs in the early evening suggests that the use of headgear right after dinner and wearing it until the next morning is an ideal schedule. [11] Various types of headgears are used depending on the vertical facial pattern (determine the anchorage location). Alternatively, the headgear facebow can also be attached to a maxillary splint or functional appliance.

Skeletal Class III malocclusion

Both maxillary excess and mandibular deficiency problems contribute to skeletal Class III malocclusions. In children with both A-P and vertical maxillary deficiency, reverse pull headgear (orthopedic facemask) is the appliance of choice as it produces dramatic results in short duration (6 months) by moving the maxilla in inferior and anterior position. Treatment is started as the permanent molars erupt fully and can be used as an anchorage unit. In children with true mandibular prognathism, use of chin cup [Figure 8]a is more effective under the age of 7. However, this treatment effect is transitory and is lost with further mandibular growth. [12] Frankel III appliance [Figure 8]b produces the same results as a face mask, but the treatment duration is usually prolonged (12-24 months). It is indicated when improvement of the overall soft-tissue appearance of the patient is of great concern. [13]
Figure 8: Growth modification for skeletal class III malocclusion, (a) Chin cup therapy, (b) Frankel III appliance

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Correction of anterior cross bite

Cross bite involving all four incisors is associated with anterior mandibular shift on closure or a developing Class III skeletal base relationship. It is important to inform parents about the possibility of unfavorable growth and the need for later surgical intervention. Cross bite of one or two teeth is usually found in patients with normal facial proportions owing to the lack of space for the erupting permanent dentition.

Developing anterior cross bite with adequate spacing in the arch can be corrected by Catalan's appliance [Figure 9]a. Satisfactory correction of an anterior cross bite is possible with a Hawley's appliance incorporating "z" spring, if purely tipping movement is required [Figure 9]b. A major factor determining whether early correction of an anterior cross bite will be stable is the achievement of a positive overbite. If this can be attained, then the result requires no further retention. [14]
Figure 9: Anterior crossbite correction, (a) Catlan's appliance, (b) Hawley's with 'z' spring

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Correction of vertical problems

Children with a long face pattern generally have a maxilla rotated down posteriorly with short mandibular ramus. The ideal treatment in these patients will be to control all posterior vertical growth. This can be accomplished by high pull headgear attached to molars or maxillary splint [Figure 10]a. Short face problems are easily treated by opening the deep bite with a maxillary anterior bite plate [Figure 10]b or cervical pull headgear.
Figure 10: (a) Max. splint with headgear. (b) Anterior bite plate

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Correction of transverse problems

Maxillary arch expansion is utilized in early mixed dentition to correct posterior cross bite, treatment of TSALD problems and to allow spontaneous correction of mild Class II mandibular retrusion. If segmental posterior cross bite is left untreated, it leads to lateral functional shift of mandible producing alteration in normal growth pattern. This result in skeletal facial asymmetry. [15] Ideal maxillary intermolar width in mixed dentition is 33-35 mm. In patients with constricted maxilla, orthopedic arch expansion allows more space for alignment of the permanent dentition and alleviate potential crowding. [16] Many Class II malocclusions have a strong skeletal component. In these cases, maxillary arch expansion disrupts the occlusion and allows the mandible to be placed forward and eliminates the sagittal discrepancy. [17]

The appliance of choice is a bonded acrylic splint rapid maxillary expander [Figure 11]. The maxillary arch is over expanded until the maxillary posterior lingual cusps approximate the mandibular buccal cusps. Active orthopedic expansion produces midline diastema, which spontaneously closes during the retention period. Other slow expanders that can be used include: Removable appliances like jackscrews, coffin spring and fixed expanders like quad helix or prefabricated Ni-Ti expanders [Figure 12]. 3-4 months after arch expansion, 2 × 4 appliance can be used to align/intrude/retract the incisors depending on the patient needs.
Figure 11: Bonded hyrax appliance (note the midline diastema produced)

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Figure 12: Slow maxillary arch expanders

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Active mandibular arch expansion is contraindicated as the mandibular intercanine width is relatively stable. However, spontaneous up righting and decrowding of lower anteriors and routine improvement in intercanine width is noticed in patients undergoing maxillary arch expansion, lip bumper therapy or treatment with Frankel II appliance.

Fixed appliance treatment in mixed dentition

Irregularly erupting anterior teeth have a very significant effect on the psychological well-being of an individual and hence should be managed as early as possible. [18] The advantage of utilizing a simple fixed appliance such as the 2 × 4 appliance (2 bands cemented on both upper first permanent molars and 4 brackets bonded onto the erupted maxillary incisors) in these patients [Figure 13]a include minimal patient discomfort and hence improved co-operation, increased control of force magnitude and that controlled tooth movement is possible in all three planes of space. The control afforded with 2×4 appliance is also preferred during the correction of anterior cross bites [Figure 13]b if bodily movement is required. [19]

Adequate care can be taken to prevent damage due to the proximity of their roots with that of the crown of the developing permanent canine. Utility arches placed along with the 2 × 4 appliance produce intrusion, protraction or retraction of incisors depending on the treatment needs.
Figure 13: 2 × 4 appliance for, (a) Alignment of incisors, (b) Anterior cross bite correction

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Timing and length of fixed appliance treatment in mixed dentition

Treatment may start as soon as sufficient permanent teeth have erupted and the child is co-operative enough to have separators placed, bands cemented and brackets bonded. It is essential that the patient is capable of maintaining a high standard of oral health. Treatment carried out in this mixed dentition stage may take as little as a couple of weeks, [20] but in the more difficult cases can take longer. Definitive fixed appliance treatment will probably still be necessary in the permanent dentition, but the complexity and duration of this may be significantly reduced.


  Conclusion Top


Today's parents do not accept the answers given by some dentists and orthodontists when observing that their son or daughter has a problem. The answers such that- "no treatment is indicated at this age, the patient is too young, the malocclusion will be treated when the permanent teeth erupt in"-seems absolutely irrelevant when it is proven that malocclusions left untreated worsen over time. The functional improvement coupled with the psychological benefit gives a significant advantage for treating potentially challenging mixed dentition problems. The best timing of orthodontic treatment is a decision made by the general dentist and the orthodontist based on all the factors that enables the ideal treatment suitable for the patient.

 
  References Top

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Baccetti T, Franchi L, McNamara JA Jr, Tollaro I. Early dentofacial features of Class II malocclusion: A longitudinal study from the deciduous through the mixed dentition. Am J Orthod Dentofacial Orthop 1997;111:502-9.  Back to cited text no. 7
    
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Proffit WR. Contemporary orthodontics. 4 th ed. Ch. 9. Missouri: Mosby Inc; 2007. p. 355.  Back to cited text no. 11
    
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Proffit WR. Contemporary orthodontics. 4 th ed. Ch. 13. Missouri: Mosby Inc; 2007. p. 508.  Back to cited text no. 12
    
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McNamara JA Jr, Brudon WL. Orthodontic and Orthopedic Treatment in the Mixed Dentition. Ch. 6. AnnArbor, MI: Needham Press; 1993. p. 121-2.  Back to cited text no. 13
    
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Gu Y, Rabie AB, Hägg U. Treatment effects of simple fixed appliance and reverse headgear in correction of anterior crossbites. Am J Orthod Dentofacial Orthop 2000;117:691-9.  Back to cited text no. 14
    
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Graber TM, Vanarsdall RL. Orthodontics: current principles and techniques. 3 rd ed. Ch.11. St. Louis: Elsevier Mosby; 2000. p. 527-8.  Back to cited text no. 15
    
16.
McNamara JA Jr, Brudon WL. Orthodontic and orthopedic treatment in the mixed dentition. 5 th ed. Ch. 4. Ann Arbor (MI): Needham Press; 1995. p. 73-5.  Back to cited text no. 16
    
17.
Dowsing P, Sandler PJ. How to effectively use a 2 x 4 appliance. J Orthod 2004;31:248-58.  Back to cited text no. 17
    
18.
Ninou S, Stephens C. The early treatment of posterior crossbites: A review of continuing controversies. Dent Update 1994;21:420-6.  Back to cited text no. 18
    
19.
Shaw WC, O′Brien KD, Richmond S, Brook P. Quality control in orthodontics: Risk/benefit considerations. Br Dent J 1991;170:33-7.  Back to cited text no. 19
    
20.
Skeggs RM, Sandler PJ. Rapid correction of anterior crossbite using a fixed appliance: A case report. Dent Update 2002;29:299-302.  Back to cited text no. 20
    
21.
Graber TM, Vanarsdall RL. Orthodontics: current principles and techniques. 3 rd ed. Ch.11. St. Louis: Elsevier Mosby; 2000. p. 522.  Back to cited text no. 21
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13]
 
 
    Tables

  [Table 1]


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