|Year : 2013 | Volume
| Issue : 2 | Page : 126-131
Modified serial extraction in a case with missing mandibular second premolars and a brief review of related treatment modalities
P Chalakkal1, Ida de Noronha de Ataide2, F Akkara3, G Malhotra4
1 Department of Pedodontics and Preventive Dentistry, Goa Dental College and Hospital, Bambolim, Goa, India
2 Department of Conservative Dentistry and Endodontics, Goa Dental College and Hospital, Bambolim, Goa, India
3 Department of Oral and Maxillofacial Surgery at Goa Dental College and Hospital, Bambolim, Goa, India
4 Department of Pedodontics and Preventive Dentistry, Teerthanker Mahaveer Dental College and Research Centre, Moradabad, Uttar Pradesh, India
|Date of Web Publication||26-Jul-2013|
Department of Pedodontics and Preventive Dentistry, Goa Dental College and Hospital, Bambolim, Goa 403 202
Source of Support: None, Conflict of Interest: None
| Abstract|| |
This article discusses a case of an 8-year-old female child who presented with severe lower anterior crowding and congenitally missing lower second premolars. A conventional serial extraction procedure could not be performed due to the congenital absence of teeth. Instead, planned extraction of a few primary teeth was done to relieve the lower anterior crowding, the results of which were near satisfactory.
Keywords: Absent, congenital, mandibular second premolar, missing, serial extraction
|How to cite this article:|
Chalakkal P, de Ataide IN, Akkara F, Malhotra G. Modified serial extraction in a case with missing mandibular second premolars and a brief review of related treatment modalities. J Indian Soc Pedod Prev Dent 2013;31:126-31
|How to cite this URL:|
Chalakkal P, de Ataide IN, Akkara F, Malhotra G. Modified serial extraction in a case with missing mandibular second premolars and a brief review of related treatment modalities. J Indian Soc Pedod Prev Dent [serial online] 2013 [cited 2020 Feb 24];31:126-31. Available from: http://www.jisppd.com/text.asp?2013/31/2/126/115719
| Introduction|| |
After third molars, the mandibular second premolars (M5) have the highest incidence of congenital absence. M5 are congenitally absent in 2.5-4% cases and are bilaterally absent in 60% of such cases. , The treatment options for managing a case during the mixed dentition period with congenitally missing M5 range from extraction of the corresponding mandibular primary second molars (ME) and subsequent space closure, or prosthetic replacement; hemisection; slicing or even retaining the ME. However, if the above condition is coupled with severe crowding in the lower anterior segment, the above treatment protocols may not bring about desirable results because we will now need to deal with two problems simultaneously. This article discusses such a case where treatment consisted of selective removal of a few mandibular teeth to resolve anterior crowding along with spontaneous closure of extraction spaces by physiologic movement of permanent mandibular teeth.
| Case Report|| |
An 8-year-old female patient reported to the department of pedodontics complaining of tenderness in the mandibular posterior teeth. She presented with a bilaterally symmetrical face with a straight pleasing profile. On intraoral examination, all quadrants presented with primary canines and molars along with lower anterior crowding [Figure 1] and [Figure 2]. All permanent incisors and first molars were erupted except 16, 12, and 22. Anteriorly, an open bite was present due to insufficient eruption of 11 and 21 [Figure 3]. There was severe caries, tenderness to percussion and pain on lying down in relation to 54, 64 and ME. Radiographs revealed periapical radiolucencies in relation to 54, 64, and ME. A diagnosis of chronic irreversible pulpitis was made for these teeth and they were treated with pulpectomies followed by stainless steel crown placement [Figure 4] and [Figure 5]. An orthopantomograph revealed congenitally missing 12, 15, 22, and M5 [Figure 6].
|Figure 4: Maxillary view after pulpectomy and stainless steel crown placement on 54 and 64|
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|Figure 5: Mandibular view after pulpectomy and stainless steel crown placement on 75 and 85|
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The patient and her parents were made aware of the lower anterior crowding and the need for early intervention. The treatment objective was to selectively extract a few mandibular teeth in order to resolve lower anterior crowding; idealize the overbite; and to finish with class I molar relation with no residual spaces. The advantages and disadvantages of the procedures to be carried out were explained to the patient and parental consent was obtained for the same. Since M5 were congenitally missing, it was not possible to perform a conventional serial extraction procedure. Therefore, instead of a C-D-4 extraction sequence, it was planned to perform a C-D-E extraction sequence. It was planned to delay the extractions since her lower lateral incisors were insufficiently erupted. However, extraction of 52 was done immediately to aid in early space closure between 11 and 53, as 12 and 22 were congenitally missing.
After 6 months, the patient was recalled and alginate impressions were made of both the arches. Study casts were prepared and the following analysis was carried out:
- Carey's analysis for the lower arch which revealed a tooth size arch length discrepancy of 11 mm. However, the upper arch showed no space deficiency
- The proportional equation method using the formula: X1 Χ Y2 = Y1 Χ X2, where X1 is the unerupted tooth width; X2 is the unerupted tooth width on the radiograph; Y1 is the erupted tooth width on the cast; and Y2 is the erupted tooth width on the radiograph.
The available space for the mandibular permanent canines (M3) and first premolars (M4) after incisor alignment was found to be 21 mm, bilaterally. However, the combined mesiodistal widths of M3 and M4 were found to be 16 mm on each side. The space required by the lower permanent first molars (M6) to drift mesially into class I molar relationship was found to be 3 mm, bilaterally. This reduced the available space for M3 and M4 to 18 mm, bilaterally. By subtracting the available space with the combined mesiodistal widths of these teeth (18 minus 16 mm), the excess space available for the eruption of M3 and M4 was found to be 2 mL, bilaterally.
The lower primary canines (MC) were extracted and further extractions were delayed until the lower anteriors aligned favorably [Figure 7]. Lower anterior alignment occurred in 6 months, following which the lower primary first molars (MD) were extracted, coincident with half root development of M4 [Figure 8]. ME were extracted soon after M3 cusp tips were visible intraorally [Figure 9]. The eruption of M4 simultaneous with mesial migration of M6 into the extraction spaces occurred 8 months after the extraction of ME [Figure 10]. In the maxilla, 14, 23, and 24 had erupted and 53 was nearing exfoliation [Figure 11].
|Figure 7: Mandibular view after incisor alignment following extraction of the primary canines|
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|Figure 8: Orthopantomograph following extraction of the mandibular primary fi rst molars coincident with half root development of the mandibular fi rst premolars|
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|Figure 11: Maxillary view following treatment in the mandibular|
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The following results were obtained after 18 months since the extraction of MC:
- The upper central incisors erupted well into the occlusal plane compared to when the patient had first reported for treatment [Figure 3] and [Figure 12]. A midline shift (2 mL toward the right side) which was present before treatment was initiated, was still apparent
- There was good approximation between teeth in both arches [Figure 13]. On the patient's left side, there was class I molar relationship [Figure 14]. However, on the right side, there was buccal displacement of 14 along with a class III molar relationship [Figure 15]
- An overjet of 2 mm was present anteriorly.
| Discussion|| |
ME, in the absence of successors are known to last for 2-3 decades. ,,, In fact, they have been found to remain stable after 20 years of age with no further root resorption.  However, maintaining ME also brings about the problem of Boltons' tooth size discrepancy between ME and M5 (1.5-2 mm), altering occlusion.  Moreover, optimal interdigitation between teeth do not occur due to the large mesiodistal width of ME.  Also, when ME eventually exfoliate, the mesiodistal space left behind is too large for optimal prosthetic replacement. Retaining ME also brings about the risk of ankylosis that may result in infraocclusion, ditching of adjacent teeth, and supraeruption of antagonist teeth. Implant replacement for M5 cannot be done in children due to incompletion of alveolar growth, , neither can a fixed partial denture be placed due to the presence of large pulp chambers.  However, we did not consider the option of retaining ME, because the treatment plan for the child's lower anterior crowding eventually needed extraction of ME.
Hemisection of ME has been suggested by various authors. ,, The procedure was introduced so that the atrophy of the alveolus could be minimized in a small extraction site. The procedure includes the removal of the distal half of ME to aid in mesial migration of M6. Once M6 nears the mesial half of ME, the mesial half (''bookend'') is extracted so that M4 could migrate distally and approximate with M6. The forces of occlusion help in the gradual mesial movement of M6 through the buccolingual width of the alveolar plates whose thickness is maintained by the residual mesial segment of ME, avoiding unwanted mesial rotation of M6. 
However, the disadvantages of this method include: The bookend of ME does not move distally; the distal movement of M3 and M4 result in midline shift; and the lower anteriors tip lingually increasing the overjet and decreasing lip support.  We did not incorporate hemisection in the treatment plan because the edentulous space after extraction of ME had to be occupied simultaneously by the eruption of M4 and by mesial migration of M6, rather than closure of the space merely by mesial and distal migration of M6 and M4, respectively.
Mesiodistal slicing of ME to make it equal to the mesiodistal width of M5, so that class I molar relationship may be established, has also been suggested. , However, dentin exposure (mesiodistally) and the resultant large contact areas produced after slicing make ME vulnerable to dental caries and periodontal problems. Moreover, the divergent roots of ME prevent its close approximation with adjacent teeth.  However, this method was not an option in our treatment plan because the space requirement needed complete elimination of ME.
Extraction of ME to resolve crowding in the arch has been supported by a few authors. , It has been proved that early extraction of ME results in mesial rotation of 6 in 46% cases, and out of 80% closures, distal drifting of M3 and M4 occur.  The results from our study differ from that of Valencia et al.,  who claimed that plain extraction of ME showed average to poor results in 75% cases. However, our results were near satisfactory in the lower arch. After extraction of ME, 25% ridge width decrease occurs within 3-4 years.  Moreover, the amount of buccal ridge resorption (74%) was found to be more than that of the lingual ridge (24%).  However, ridge resorption would have been minimal in this case, because after the extraction of ME, the edentulous space was occupied by M4 and M6 in less than a year's time. Our findings are similar to those of Lindqvist,  who found that extraction of ME at 9 years, before the completion of root formation of M4 and emergence of the mandibular second molar, eventually results in spontaneous space closure. Although, a vertical defect occurs soon after extraction of ME, subsequent tooth eruption and movement brings the bone and tissue up to normal height.  Moreover, regional acceleratory phenomenon (osteopenia) that occurs soon after an extraction provides a time period when adjacent teeth move rapidly. 
Eventually, the patient might need fixed orthodontic therapy for the correction of the buccally erupted 14; the midline shift; and the unilateral class III molar relationship. However, the lower anterior crowding was corrected purely by extractions and spontaneous movement of teeth. The extraction of MC would have caused some amount of lingualization of the lower incisors that improved the interincisor relationship, which initially seemed to be in edge-to-edge incisor relationship [Figure 3]. Although M6 would have moved anteriorly with a little amount of tipping, M4 would have erupted into the space without tipping. The advantage of such corrections is that the movement of teeth is purely physiologic, thus eliminating the need for any retentive device or the fear of periodontal breakdown. There was no appreciable change in the patients profile after treatment. The class III molar relation may self correct after the exfoliation of 55. But since 15 is congenitally missing, the time of exfoliation of 55 cannot be ascertained. We believe that the reason for a class III malocclusion on her right side was due to late eruption of 16. The absence of occlusal forces (between 16 and 46) would have resulted in rapid mesial movement of 46. We recommend future studies using the above procedure on large number of subjects so that more concrete results may be derived from using this alternative method to serial extraction.
| Conclusion|| |
A modified serial extraction sequence (C-D-E) would be effective in resolving severe lower anterior crowding combined with congenitally missing lower second premolars. However, fixed orthodontic treatment may be required for complete correction.
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[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], [Figure 14], [Figure 15]