- Email: [email protected]
Distalization of the entire maxillary arch in an adult
CASE REPORT
Distalization of the entire maxillary arch in an adult Seung-Hyun Kyung,a Joo Yong Lee,b Ji Won Shin,c Christine Hong,d Victor Dietz,e and Anthony A. Gianellyf Boston, Mass, and Seoul, Korea
Many appliances are available to move maxillary molars distally. First molars have routinely been moved distally with nickel-titanium coil springs and nickel-titanium wire before the eruption of the second molars. However, when first molars are moved distally after the eruption of the second molars, they tend to move slowly, and anchorage loss increases. In adults, the midpalatal area is appropriate for placing titanium miniscrews for orthodontic anchorage. This case report demonstrates the ability of midpalatal miniscrews to control anchorage while distalizing the entire maxillary dentition in an adult, with improvements in lip profile resulting from the retraction of anterior teeth followed by a good response of the lips. This report suggests that absolute anchorage can be established by placing miniscrews in the palate and that miniscrew anchorage can serve as anchorage for the distal movement of an entire arch. (Am J Orthod Dentofacial Orthop 2009;135:S123-32)
M
any appliances, including repelling magnets,1,2 Wilson’s arch,3 distal jet,4 and Jones jig,5 are available to move maxillary molars distally. First molars have been moved distally before the eruption of the second molars with nickel-titanum coil springs6 and nickel-titanum wire with a modified Nance appliance as anchorage.7 However, when first molars are moved distally after the eruption of the second molars, they tend to move slowly, and anchorage loss increases.7 Recently, various orthodontic miniscrews (small, immediate load titanium screws) have been introduced as anchorage for molar distalization without patient compliance. A few reports showed that molars were distalized successfully with virtually no anchorage loss when a Visiting professor, Department of Orthodontics, School of Dental Medicine, Boston University, Boston, Mass; associate professor, Department of Orthodontics, Institute of Oral Health Science, Samsung Medical Center, Seoul, Korea. b Private practice, Seoul, Korea. c Resident, Department of Orthodontics, Institute of Oral Health Science, Samsung Medical Center, Seoul, Korea. d Orthodontic resident, Orthodontic Department, University of California, Los Angeles. e Associate professor and program director, Department of Orthodontics, School of Dental Medicine, Boston University, Boston, Mass. f Professor and chairman emeritus, Department of Orthodontics, School of Dental Medicine, Boston University, Boston, Mass. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. Reprint requests to: Anthony A. Gianelly, Department of Orthodontics, Boston University, Goldman School of Dental Medicine, Boston, MA 02118-2392; email, [email protected]. Submitted, February 2007; revised and accepted, January 2008. 0889-5406/$36.00 Copyright © 2009 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2008.01.015
anchorage was intraosseous, even though the second molars were fully erupted. Keles et al8 used a palatal implant as anchorage when distalizing the first and second molars. Byloff et al,9 Kircelli et al,10 and Oncag et al11 distalized 4 maxillary molars simultaneously with a pendulum appliance anchored to a miniscrew placed in the anterior palate. Sugawara et al12 moved maxillary molars distally with no anchorage loss in an adult, using a miniplate as anchorage. The intraosseous anchorage devices used when distalizing maxillary molars have been placed mostly in the palate rather than in the buccal area. Probably, this is because the palatal area is far from the path that the teeth travel, whereas intraosseous anchorage placed in the buccal bone of the alveolus crosses the path of tooth movement. Small orthodontic miniscrews are placed in all palatal areas except the incisive foramen, greater palatine foramen, and greater palatine nerve and vessels.13 In an adult, the midpalatal area is an appropriate area to place titanium miniscrews for orthodontic anchorage. The purpose of this case report is to demonstrate the ability of midpalatal miniscrews to control anchorage while distalizing the entire maxillary dentition in an adult. DIAGNOSIS
A 22-year-old woman visited the clinic of the orthodontic department of the Samsung Medical Center, Seoul, Korea (Figs 1-4, Table I). She was concerned about her protrusive lips. In the frontal view of her face, the mandible was deviated to the left, and the mandibuS123
S124
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Fig 1. Pretreatment facial and intraoral photographs.
Fig 2. Pretreatment dental casts.
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 4, Supplement 1
S125
Fig 3. Pretreatment cephalometric and panoramic radiographs.
lar dental midline was deviated 1.5 mm to the left as a result of the facial asymmetry. The maxillary dental midline was coincident with the facial midline. In the profile view, there was an acute nasolabial angle (86.5º), a shallow labiomental sulcus, and an obtuse pogonionmenton angle (110.5º); incompetent lips were apparent. The first premolars on both sides of the maxilla were congenitally missing. On the mandibular left side, the second deciduous molar was retained, and the second premolar was congenitally missing. The molar relationship was Class II with a dental crossbite near the mandibular left lateral incisors to the first premolar. There were 3 mm of interdental spaces in the maxillary arch and mild crowding in the mandibular arch. The temporomandibular joint evaluation was negative. Cephalometric analysis showed that the anterior teeth were located forward and protruded (1/ to NA, 34º/11.5 mm; /1 to NB, 42º/11 mm) followed by lip protrusion (UL to E-line, 3 mm; LL to E-line, 5 mm). Measurements for skeletal relationships were within the normal range (SNA, 82º; SNB, 80º; ANB, 2º). TREATMENT OBJECTIVES
The treatment objectives for this patient were to reduce lip protrusion, establish Class I molar and canine
Fig 4. Pretreatment cephalometric tracing. Angular measurement and Pancherz analysis: linear measurements from OLp (occlusal line perpendicular through sella) to each landmark. A, A-point; UL, upper lip; LL, lower lip; CUM, crown of upper molar; AUM, apex of upper molar; CUI, crown of upper incisor; AUI, apex of upper incisor; CLM, crown of lower molar; ALM, apex of lower molar; CLI, crown of lower incisor; ALI, apex of lower incisor.
S126
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Table I. Pretreatment and posttreatment cephalometric measurements Measurement
Pretreatment
Posttreatment
Difference
Postretention (1 y 3 mo)
(mean ± SD of normal value) Angular (º) SNA SNB ANB SN-MP 1/ to NA /1 to NB L1-MP Interincisal angle Nasolabial angle* Pogonion-menton angle† Linear (mm) UL to E-line LL to E-line 1/ to NA /1 to NB
82 80 2 33 35 41 108 102.5 86.5 110.5
80 (82 ± 3) 79 (79 ± 3) 1 (2 ± 1) 32.5 (31 ± 5) 25 (25 ± 5) 22 (27 ± 5) 89 (96 ± 6) 133 (124 ± 8) 92 (92 ± 9) 92 (88 ± 8)
2 1 1 0.5 8.5 22 19 –30.5 –5.5 18.5
80 79 1 33 20 21 88 136 91 92
3 5 11.5 11
–1 (–1 ± 2) –0.5 (0 ± 2) 4 (8 ± 2) 3 (8 ± 2)
4 5.5 4.5 5.5
–1 –0.5 4 4
*Cm-Sn-Ls. †SmPog´-ThMe´ (Sm, submentale; Pog´, soft-tissue pogonion; Th, throat; Me´, soft-tissue menton).
relationships, correct the dental asymmetry, close the spaces from the congenitally missing teeth, and correct the dental crossbite. TREATMENT ALTERNATIVES
A plan for the protrusive lips was to retract the anterior teeth after gaining the space for retraction. There are a few options to create space in the maxillary arch. The first option was to distalize the first and second molars after extracting the third molars. All maxillary teeth would then be moved backward. The second option was to extract the second molars and distalize the first molars. A disadvantage of this option was that the size and morphology of third molars were in doubt. The third option was to extract the maxillary first molars. A disadvantage of this was that the first molar plays an important a role in mastication. In the mandibular arch, we would gain the space for lip retraction by extracting the right first premolar and the retained second deciduous molar and retracting the mandibular incisors. Difficulties were expected in correcting the mandibular dental midline, which deviated 1.5 mm to left. Another unfavorable condition concerning the midline discrepancy was the differences of the spaces to be closed. The mesiodistal width of the right first premolar was 7.7 mm, whereas the left second deciduous molar was 10.3 mm. Symmetric space closure could make the lower midline deviate more to the left unless the mandibular left molar were protracted 2 to 3 mm relative to the right molar. Therefore, if anchorage loss did not occur in the right posterior segment, the left molar should be moved 2.6 mm forward, and the result
would maintain the preexisting mandibular dental midline. Irrespective of the options, midpalatal miniscrews would be used as anchorage for the distalization of the maxillary molars. The impacted third molars would be removed to facilitate distal movement of the maxillary molars. TREATMENT PROGRESS
The treatment plan required distalization of the first and second molars after extraction of the third molar in the maxillary arch and extraction of the right first premolar and the retained left deciduous second molar in the mandibular arch. To obtain absolute anchorage, a screw-supported S-sheath was fabricated on the palate. Two midpalatal miniscrews were placed by using a contra-angle handpiece. Although the miniscrews seemed to perforate the nasal cavity on a lateral cephalometric radiograph, they were within the bone. The nasal crest was apparent on the posteroanterior cephalometric radiograph (Fig 5). A customized sheath was cemented on the top of 2 miniscrews with flowable composite resin, and a removable hook was placed into the sheath. A mesially extended transpalatal arch (ME-TPA) was placed in the lingual sheath of the maxillary first molar. Elastics were placed from anterior hooks of the ME-TPA to distal hooks extending from the S-sheath to the TPA (Fig 6, A). Preadjusted 0.018-in brackets were placed first on the mandibular teeth to correct the crossbite during the initial stages of treatment. Five months after treatment started, some space was gained by distal movement of the maxillary molars, and the crossbite had been corrected (Fig 6, A).
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 4, Supplement 1
S127
Fig 5. Midpalatal miniscrews were in the bone of the nasal crest.
Fig 6. Treatment progress: A, 5 months after start of treatment; B, 7 months after start of treatment.
Preadjusted .018-in brackets were also placed on the maxillary teeth. Seven months after treatment started, the maxillary molars were distalized into a Class I molar relationship. The ME-TPA was replaced with a modified TPA to maintain the position of the maxillary first molars (Fig 6, B). After leveling and alignment, a .017 × .025-in stainless steel wire was used for space closure to control the torque of the anterior teeth. The posterior part of the wire was slenderized so that the wire moved easily backward through the brackets and molar tubes. A .016 × .022-in stainless steel wire was used for space closure in the mandible. A miniscrew was placed on the right buccal area between the first and second molars to maintain anchorage. Class II elastics were used on the left for mesial movement of the mandibular left molars. Total treatment time was 2 years 4 months. Maxillary
molar distalization took approximately 7 months, and alignment and retraction of the anterior teeth took about 21 months. TREATMENT RESULTS
The posttreatment facial photographs showed a remarkable improvement in lip profile resulting from the large amount of retraction of anterior teeth and lips. Cephalometric superimposition indicated that the maxillary molars were distalized about 5 mm at crown level and 3 mm at apex level. The maxillary incisors were retracted about 7 mm and the mandibular incisors about 7.5 mm at crown level (Figs 7-9, Table II). The upper lip moved backward about 4.5 mm and the lower lip 5.5 mm; both were located in the normal range of the E-line (upper, –1 mm; lower, –0.5 mm). The appropriate labiomental sulcus, nasolabial angle (92º), and interincisal
S128
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Fig 7. Posttreatment facial and intraoral photographs.
Fig 8. Posttreatment dental casts.
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 4, Supplement 1
S129
Table II. Pancherz analysis: differences between pretreatment and posttreatment Linear from OLp (mm) Upper lip Lower lip A-point Crown of maxillary molar Apex of maxillary molar Crown of maxillary incisor Apex of maxillary incisor Crown of mandibular molar Apex of mandibular molar Crown of mandibular incisor Apex of mandibular incisor
Pretreatment
Posttreatment
Difference
Postretention (1 y 3 mo)
96 95.5 74 58.5 52 86.5 70.5 56.5 49.5 84.0 71.5
91.5 90 72.5 53.5 48.5 79.5 66.0 57.5 49.5 76.5 69.5
4.5 5.5 1.5 5.0 3.5 7.0 4.5 –1.0 0.0 7.5 2
91.5 95.5 73.0 54.5 49.0 80.0 67.5 57.5 49.5 76.5 69.5
Fig 9. Posttreatment cephalometric and panoramic radiographs.
angle (133º) were also achieved.14 Another observation was that the nose looked higher, and the chin looked as if it had advanced forward as the lips moved backward. The asymmetry in the lower face improved as a result of the camouflage treatment of the crossbite correction, and the improvement was still evident in the postretention period (Figs 10-12). However, the skeletal asymmetry of the mandible and the deviated mandibular dental midline remained unchanged. Even though cephalometric superimposition of the postretention radiograph showed a slight mesial relapse of the entire maxillary arch, there were no obvious changes in the occlusal relationships (Fig 12).
DISCUSSION
The patient had 2 problems in the maxilla: congenitally missing teeth and protrusive lips. The protrusive lips were resolved by moving the anterior teeth into the space created by the distalization of the maxillary posterior teeth with miniscrews as anchorage. The third molars on both sides were removed to facilitate backward movement of the teeth. It took only 7 months to achieve a Class I molar relationship. This suggested that the appliance and force system were efficient, particularly since the maxillary first molar was tipped mesially at the start of treatment. Facial asymmetry reflected the asymmetric mandible, which was also the cause of the mandibular dental midline deviation
S130
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Fig 10. Postretention facial and intraoral photographs.
to the left. The position of the mandibular dental midline was not changed at posttreatment. On cephalometric superimposition after treatment, the mandibular molars looked as if they had moved slightly mesially.This might have resulted from forward movement of the mandibular left molar that required protraction, not the right molar. After treatment, the mandibular plane angle had closed slightly (from 33.0º to 32.5º) after intrusion of the maxillary molar. The mandible tends to open as the maxillary molar moves backward, because the occlusal plane has a curve of Spee. Therefore, it is necessary to intrude maxillary the molars during distalizing so that the mandible cannot open. Cephalometric superimposition showed that the mandible closed after intrusion of the maxillary molars (Fig 12). In this adult, the miniscrews were placed in the midpalatal suture area, since growth had been completed (the area of the midpalatal suture should be avoided in adolescents because of possible damage to the developing suture). Wehrbein et al15 reported that the vertical
bone support is at least 2 mm higher than indicated on a lateral cephalogram in their study using dry skulls. The nasal crest exists midsagitally between the anterior nasal spine and the posterior nasal spine. The nasal crest has a triangular shape seen from the front. The average size of an adult is 5.4 mm in baseline and 5.6 mm in height16; this is enough to support the miniscrew. Therefore, the area for bone support is large enough. Also, bordered by the oral and nasal cavities and the maxillary sinuses lining the cortical bone, the palate is composed mostly of cortical bone; this means that the palatal area provides a more stable bony bed. In addition, the covering soft tissue is keratinized; this is beneficial to minimize inflammation in the midpalatal area; its thickness is consistent at 1 mm, enough to support a small titanium miniscrew.17 When the force was applied on the palatal side, the molar segment rotated mesially, and the intermolar width increased. The ME-TPA should be activated to counteract these complications (Fig 13, A). The types of movement were determined by the direction of the force vectors in relation to the center of resistance of the
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 4, Supplement 1
S131
Fig 11. Postretention cephalometric and panoramic radiographs.
Fig 12. Pretreatment, posttreatment, and postretention cephalometric tracings superimposed on SN line.
molar segment. When root movement was needed, the vertical position of the hook on the ME-TPA and S-sheath should be adjusted so that the force vector goes above the center of resistance of the molar segment (Fig 13, B). When the force vector goes below the center of resistance, the molar tips distally (Fig 13, C). The molar will be intruded and distalized with the force vector going backward and upward (Fig 13, D). The
procedure for adjustment can be done easily because the ME-TPA and hook from the S-sheath are removable. CONCLUSIONS
1. Absolute anchorage can be established by placing miniscrews in the palate. 2. Miniscrew anchorage can serve as anchorage for the distal movement of an entire arch.
S132
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Fig 13. Biomechanics of the ME-TPA: A, complications in distal movements; B, translation; C, distal tipping; D, disto-intrusion. REFERENCES 1. Gianelly AA, Vaitas AS, Thomas WM. The use of magnets to move molars distally. Am J Orthod Dentofacial Orthop 1989;96:161-7. 2. Gianelly AA, Vaitas AS, Thomas WM, Berger OG. Distalization of molars with repelling magnets. J Clin Orthod 1988; 22:40-4. 3. Wilson WL, Wilson RC. Multi-directional 3D functional Class II treatment. J Clin Orthod 1987;21:186-9. 4. Carano A, Testa M. The distal jet for upper molar distalization. J Clin Orthod 1996;30:374-80. 5. Jones R, White J. Rapid Class II molar correction with an open coil jig. J Clin Orthod 1992;26:661-4. 6. Gianelly A, Bednar J, Dietz V. Japanese NiTi coils used to move molars distally. Am J Orthod Dentofacial Orthop 1991;99:564-6. 7. Karlsson I, Bondemark L. Intraoral maxillary molar distalization. Angle Orthod 2006:76:923-9. 8. Keles A, Erverdi N, Sezen S. Bodily distalization of molars with absolute anchorage. Angle Orthod 2002;73:471-82. 9. Byloff FK, Kärcher H, Clar E, Stoff F. An implant to eliminate anchorage loss during molar distalization: a case report involving the Graz implant-supported pendulum. Int J Adult Orthod Orthognath Surg 2000;15:129-37.
10. Kircelli BH, Pektas ZO, Kircelli C. Maxillary molar distalization with a bone-anchored pendulum appliance. Angle Orthod 2006;76:650-9. 11. Oncag G, Akyalçın S, Arıkan F. The effectiveness of a single osteointegrated implant combined with pendulum springs for molar distalization. Am J Orthod Dentofacial Orthop 2007;131:277-84. 12. Sugawara J, Kanzaki R, Takahashi I, Nagasaka H, Nanda R. Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system. Am J Orthod Dentofacial Orthop 2006;129:723-33. 13. Kyung SH, Hong SG, Park YC. Distalization of maxillary molars with midpalatal miniscrew. J Clin Orthod 2003:37;22-6. 14. Hwang HS, Kim WS, McNamara JA Jr. European-American adults with normal occlusions well-balanced faces. Angle Orthod 2002;72:72-80. 15. Wehrbein H, Merz BR, Diedrich P. Palatal bone support for orthodontic implant anchorage—a clinical and radiological study. Eur J Orthod 1999;21:65-70. 16. Lang J. Clinical anatomy of the nose, nasal cavity and paranasal sinuses. New York: Thieme; 1989. p.103. 17. Kim HJ, Yun HS, Park HD, Kim DH, Park YC. Soft-tissue and cortical-bone thickness at orthodontic implant sites. Am J Orthod Dentofacial Orthop 2006;130:177-82.
Distalization of the entire maxillary arch in an adult Seung-Hyun Kyung,a Joo Yong Lee,b Ji Won Shin,c Christine Hong,d Victor Dietz,e and Anthony A. Gianellyf Boston, Mass, and Seoul, Korea
Many appliances are available to move maxillary molars distally. First molars have routinely been moved distally with nickel-titanium coil springs and nickel-titanium wire before the eruption of the second molars. However, when first molars are moved distally after the eruption of the second molars, they tend to move slowly, and anchorage loss increases. In adults, the midpalatal area is appropriate for placing titanium miniscrews for orthodontic anchorage. This case report demonstrates the ability of midpalatal miniscrews to control anchorage while distalizing the entire maxillary dentition in an adult, with improvements in lip profile resulting from the retraction of anterior teeth followed by a good response of the lips. This report suggests that absolute anchorage can be established by placing miniscrews in the palate and that miniscrew anchorage can serve as anchorage for the distal movement of an entire arch. (Am J Orthod Dentofacial Orthop 2009;135:S123-32)
M
any appliances, including repelling magnets,1,2 Wilson’s arch,3 distal jet,4 and Jones jig,5 are available to move maxillary molars distally. First molars have been moved distally before the eruption of the second molars with nickel-titanum coil springs6 and nickel-titanum wire with a modified Nance appliance as anchorage.7 However, when first molars are moved distally after the eruption of the second molars, they tend to move slowly, and anchorage loss increases.7 Recently, various orthodontic miniscrews (small, immediate load titanium screws) have been introduced as anchorage for molar distalization without patient compliance. A few reports showed that molars were distalized successfully with virtually no anchorage loss when a Visiting professor, Department of Orthodontics, School of Dental Medicine, Boston University, Boston, Mass; associate professor, Department of Orthodontics, Institute of Oral Health Science, Samsung Medical Center, Seoul, Korea. b Private practice, Seoul, Korea. c Resident, Department of Orthodontics, Institute of Oral Health Science, Samsung Medical Center, Seoul, Korea. d Orthodontic resident, Orthodontic Department, University of California, Los Angeles. e Associate professor and program director, Department of Orthodontics, School of Dental Medicine, Boston University, Boston, Mass. f Professor and chairman emeritus, Department of Orthodontics, School of Dental Medicine, Boston University, Boston, Mass. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article. Reprint requests to: Anthony A. Gianelly, Department of Orthodontics, Boston University, Goldman School of Dental Medicine, Boston, MA 02118-2392; email, [email protected]. Submitted, February 2007; revised and accepted, January 2008. 0889-5406/$36.00 Copyright © 2009 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2008.01.015
anchorage was intraosseous, even though the second molars were fully erupted. Keles et al8 used a palatal implant as anchorage when distalizing the first and second molars. Byloff et al,9 Kircelli et al,10 and Oncag et al11 distalized 4 maxillary molars simultaneously with a pendulum appliance anchored to a miniscrew placed in the anterior palate. Sugawara et al12 moved maxillary molars distally with no anchorage loss in an adult, using a miniplate as anchorage. The intraosseous anchorage devices used when distalizing maxillary molars have been placed mostly in the palate rather than in the buccal area. Probably, this is because the palatal area is far from the path that the teeth travel, whereas intraosseous anchorage placed in the buccal bone of the alveolus crosses the path of tooth movement. Small orthodontic miniscrews are placed in all palatal areas except the incisive foramen, greater palatine foramen, and greater palatine nerve and vessels.13 In an adult, the midpalatal area is an appropriate area to place titanium miniscrews for orthodontic anchorage. The purpose of this case report is to demonstrate the ability of midpalatal miniscrews to control anchorage while distalizing the entire maxillary dentition in an adult. DIAGNOSIS
A 22-year-old woman visited the clinic of the orthodontic department of the Samsung Medical Center, Seoul, Korea (Figs 1-4, Table I). She was concerned about her protrusive lips. In the frontal view of her face, the mandible was deviated to the left, and the mandibuS123
S124
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Fig 1. Pretreatment facial and intraoral photographs.
Fig 2. Pretreatment dental casts.
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 4, Supplement 1
S125
Fig 3. Pretreatment cephalometric and panoramic radiographs.
lar dental midline was deviated 1.5 mm to the left as a result of the facial asymmetry. The maxillary dental midline was coincident with the facial midline. In the profile view, there was an acute nasolabial angle (86.5º), a shallow labiomental sulcus, and an obtuse pogonionmenton angle (110.5º); incompetent lips were apparent. The first premolars on both sides of the maxilla were congenitally missing. On the mandibular left side, the second deciduous molar was retained, and the second premolar was congenitally missing. The molar relationship was Class II with a dental crossbite near the mandibular left lateral incisors to the first premolar. There were 3 mm of interdental spaces in the maxillary arch and mild crowding in the mandibular arch. The temporomandibular joint evaluation was negative. Cephalometric analysis showed that the anterior teeth were located forward and protruded (1/ to NA, 34º/11.5 mm; /1 to NB, 42º/11 mm) followed by lip protrusion (UL to E-line, 3 mm; LL to E-line, 5 mm). Measurements for skeletal relationships were within the normal range (SNA, 82º; SNB, 80º; ANB, 2º). TREATMENT OBJECTIVES
The treatment objectives for this patient were to reduce lip protrusion, establish Class I molar and canine
Fig 4. Pretreatment cephalometric tracing. Angular measurement and Pancherz analysis: linear measurements from OLp (occlusal line perpendicular through sella) to each landmark. A, A-point; UL, upper lip; LL, lower lip; CUM, crown of upper molar; AUM, apex of upper molar; CUI, crown of upper incisor; AUI, apex of upper incisor; CLM, crown of lower molar; ALM, apex of lower molar; CLI, crown of lower incisor; ALI, apex of lower incisor.
S126
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Table I. Pretreatment and posttreatment cephalometric measurements Measurement
Pretreatment
Posttreatment
Difference
Postretention (1 y 3 mo)
(mean ± SD of normal value) Angular (º) SNA SNB ANB SN-MP 1/ to NA /1 to NB L1-MP Interincisal angle Nasolabial angle* Pogonion-menton angle† Linear (mm) UL to E-line LL to E-line 1/ to NA /1 to NB
82 80 2 33 35 41 108 102.5 86.5 110.5
80 (82 ± 3) 79 (79 ± 3) 1 (2 ± 1) 32.5 (31 ± 5) 25 (25 ± 5) 22 (27 ± 5) 89 (96 ± 6) 133 (124 ± 8) 92 (92 ± 9) 92 (88 ± 8)
2 1 1 0.5 8.5 22 19 –30.5 –5.5 18.5
80 79 1 33 20 21 88 136 91 92
3 5 11.5 11
–1 (–1 ± 2) –0.5 (0 ± 2) 4 (8 ± 2) 3 (8 ± 2)
4 5.5 4.5 5.5
–1 –0.5 4 4
*Cm-Sn-Ls. †SmPog´-ThMe´ (Sm, submentale; Pog´, soft-tissue pogonion; Th, throat; Me´, soft-tissue menton).
relationships, correct the dental asymmetry, close the spaces from the congenitally missing teeth, and correct the dental crossbite. TREATMENT ALTERNATIVES
A plan for the protrusive lips was to retract the anterior teeth after gaining the space for retraction. There are a few options to create space in the maxillary arch. The first option was to distalize the first and second molars after extracting the third molars. All maxillary teeth would then be moved backward. The second option was to extract the second molars and distalize the first molars. A disadvantage of this option was that the size and morphology of third molars were in doubt. The third option was to extract the maxillary first molars. A disadvantage of this was that the first molar plays an important a role in mastication. In the mandibular arch, we would gain the space for lip retraction by extracting the right first premolar and the retained second deciduous molar and retracting the mandibular incisors. Difficulties were expected in correcting the mandibular dental midline, which deviated 1.5 mm to left. Another unfavorable condition concerning the midline discrepancy was the differences of the spaces to be closed. The mesiodistal width of the right first premolar was 7.7 mm, whereas the left second deciduous molar was 10.3 mm. Symmetric space closure could make the lower midline deviate more to the left unless the mandibular left molar were protracted 2 to 3 mm relative to the right molar. Therefore, if anchorage loss did not occur in the right posterior segment, the left molar should be moved 2.6 mm forward, and the result
would maintain the preexisting mandibular dental midline. Irrespective of the options, midpalatal miniscrews would be used as anchorage for the distalization of the maxillary molars. The impacted third molars would be removed to facilitate distal movement of the maxillary molars. TREATMENT PROGRESS
The treatment plan required distalization of the first and second molars after extraction of the third molar in the maxillary arch and extraction of the right first premolar and the retained left deciduous second molar in the mandibular arch. To obtain absolute anchorage, a screw-supported S-sheath was fabricated on the palate. Two midpalatal miniscrews were placed by using a contra-angle handpiece. Although the miniscrews seemed to perforate the nasal cavity on a lateral cephalometric radiograph, they were within the bone. The nasal crest was apparent on the posteroanterior cephalometric radiograph (Fig 5). A customized sheath was cemented on the top of 2 miniscrews with flowable composite resin, and a removable hook was placed into the sheath. A mesially extended transpalatal arch (ME-TPA) was placed in the lingual sheath of the maxillary first molar. Elastics were placed from anterior hooks of the ME-TPA to distal hooks extending from the S-sheath to the TPA (Fig 6, A). Preadjusted 0.018-in brackets were placed first on the mandibular teeth to correct the crossbite during the initial stages of treatment. Five months after treatment started, some space was gained by distal movement of the maxillary molars, and the crossbite had been corrected (Fig 6, A).
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 4, Supplement 1
S127
Fig 5. Midpalatal miniscrews were in the bone of the nasal crest.
Fig 6. Treatment progress: A, 5 months after start of treatment; B, 7 months after start of treatment.
Preadjusted .018-in brackets were also placed on the maxillary teeth. Seven months after treatment started, the maxillary molars were distalized into a Class I molar relationship. The ME-TPA was replaced with a modified TPA to maintain the position of the maxillary first molars (Fig 6, B). After leveling and alignment, a .017 × .025-in stainless steel wire was used for space closure to control the torque of the anterior teeth. The posterior part of the wire was slenderized so that the wire moved easily backward through the brackets and molar tubes. A .016 × .022-in stainless steel wire was used for space closure in the mandible. A miniscrew was placed on the right buccal area between the first and second molars to maintain anchorage. Class II elastics were used on the left for mesial movement of the mandibular left molars. Total treatment time was 2 years 4 months. Maxillary
molar distalization took approximately 7 months, and alignment and retraction of the anterior teeth took about 21 months. TREATMENT RESULTS
The posttreatment facial photographs showed a remarkable improvement in lip profile resulting from the large amount of retraction of anterior teeth and lips. Cephalometric superimposition indicated that the maxillary molars were distalized about 5 mm at crown level and 3 mm at apex level. The maxillary incisors were retracted about 7 mm and the mandibular incisors about 7.5 mm at crown level (Figs 7-9, Table II). The upper lip moved backward about 4.5 mm and the lower lip 5.5 mm; both were located in the normal range of the E-line (upper, –1 mm; lower, –0.5 mm). The appropriate labiomental sulcus, nasolabial angle (92º), and interincisal
S128
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Fig 7. Posttreatment facial and intraoral photographs.
Fig 8. Posttreatment dental casts.
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 4, Supplement 1
S129
Table II. Pancherz analysis: differences between pretreatment and posttreatment Linear from OLp (mm) Upper lip Lower lip A-point Crown of maxillary molar Apex of maxillary molar Crown of maxillary incisor Apex of maxillary incisor Crown of mandibular molar Apex of mandibular molar Crown of mandibular incisor Apex of mandibular incisor
Pretreatment
Posttreatment
Difference
Postretention (1 y 3 mo)
96 95.5 74 58.5 52 86.5 70.5 56.5 49.5 84.0 71.5
91.5 90 72.5 53.5 48.5 79.5 66.0 57.5 49.5 76.5 69.5
4.5 5.5 1.5 5.0 3.5 7.0 4.5 –1.0 0.0 7.5 2
91.5 95.5 73.0 54.5 49.0 80.0 67.5 57.5 49.5 76.5 69.5
Fig 9. Posttreatment cephalometric and panoramic radiographs.
angle (133º) were also achieved.14 Another observation was that the nose looked higher, and the chin looked as if it had advanced forward as the lips moved backward. The asymmetry in the lower face improved as a result of the camouflage treatment of the crossbite correction, and the improvement was still evident in the postretention period (Figs 10-12). However, the skeletal asymmetry of the mandible and the deviated mandibular dental midline remained unchanged. Even though cephalometric superimposition of the postretention radiograph showed a slight mesial relapse of the entire maxillary arch, there were no obvious changes in the occlusal relationships (Fig 12).
DISCUSSION
The patient had 2 problems in the maxilla: congenitally missing teeth and protrusive lips. The protrusive lips were resolved by moving the anterior teeth into the space created by the distalization of the maxillary posterior teeth with miniscrews as anchorage. The third molars on both sides were removed to facilitate backward movement of the teeth. It took only 7 months to achieve a Class I molar relationship. This suggested that the appliance and force system were efficient, particularly since the maxillary first molar was tipped mesially at the start of treatment. Facial asymmetry reflected the asymmetric mandible, which was also the cause of the mandibular dental midline deviation
S130
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Fig 10. Postretention facial and intraoral photographs.
to the left. The position of the mandibular dental midline was not changed at posttreatment. On cephalometric superimposition after treatment, the mandibular molars looked as if they had moved slightly mesially.This might have resulted from forward movement of the mandibular left molar that required protraction, not the right molar. After treatment, the mandibular plane angle had closed slightly (from 33.0º to 32.5º) after intrusion of the maxillary molar. The mandible tends to open as the maxillary molar moves backward, because the occlusal plane has a curve of Spee. Therefore, it is necessary to intrude maxillary the molars during distalizing so that the mandible cannot open. Cephalometric superimposition showed that the mandible closed after intrusion of the maxillary molars (Fig 12). In this adult, the miniscrews were placed in the midpalatal suture area, since growth had been completed (the area of the midpalatal suture should be avoided in adolescents because of possible damage to the developing suture). Wehrbein et al15 reported that the vertical
bone support is at least 2 mm higher than indicated on a lateral cephalogram in their study using dry skulls. The nasal crest exists midsagitally between the anterior nasal spine and the posterior nasal spine. The nasal crest has a triangular shape seen from the front. The average size of an adult is 5.4 mm in baseline and 5.6 mm in height16; this is enough to support the miniscrew. Therefore, the area for bone support is large enough. Also, bordered by the oral and nasal cavities and the maxillary sinuses lining the cortical bone, the palate is composed mostly of cortical bone; this means that the palatal area provides a more stable bony bed. In addition, the covering soft tissue is keratinized; this is beneficial to minimize inflammation in the midpalatal area; its thickness is consistent at 1 mm, enough to support a small titanium miniscrew.17 When the force was applied on the palatal side, the molar segment rotated mesially, and the intermolar width increased. The ME-TPA should be activated to counteract these complications (Fig 13, A). The types of movement were determined by the direction of the force vectors in relation to the center of resistance of the
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics Volume 135, Number 4, Supplement 1
S131
Fig 11. Postretention cephalometric and panoramic radiographs.
Fig 12. Pretreatment, posttreatment, and postretention cephalometric tracings superimposed on SN line.
molar segment. When root movement was needed, the vertical position of the hook on the ME-TPA and S-sheath should be adjusted so that the force vector goes above the center of resistance of the molar segment (Fig 13, B). When the force vector goes below the center of resistance, the molar tips distally (Fig 13, C). The molar will be intruded and distalized with the force vector going backward and upward (Fig 13, D). The
procedure for adjustment can be done easily because the ME-TPA and hook from the S-sheath are removable. CONCLUSIONS
1. Absolute anchorage can be established by placing miniscrews in the palate. 2. Miniscrew anchorage can serve as anchorage for the distal movement of an entire arch.
S132
Kyung et al
American Journal of Orthodontics and Dentofacial Orthopedics April 2009
Fig 13. Biomechanics of the ME-TPA: A, complications in distal movements; B, translation; C, distal tipping; D, disto-intrusion. REFERENCES 1. Gianelly AA, Vaitas AS, Thomas WM. The use of magnets to move molars distally. Am J Orthod Dentofacial Orthop 1989;96:161-7. 2. Gianelly AA, Vaitas AS, Thomas WM, Berger OG. Distalization of molars with repelling magnets. J Clin Orthod 1988; 22:40-4. 3. Wilson WL, Wilson RC. Multi-directional 3D functional Class II treatment. J Clin Orthod 1987;21:186-9. 4. Carano A, Testa M. The distal jet for upper molar distalization. J Clin Orthod 1996;30:374-80. 5. Jones R, White J. Rapid Class II molar correction with an open coil jig. J Clin Orthod 1992;26:661-4. 6. Gianelly A, Bednar J, Dietz V. Japanese NiTi coils used to move molars distally. Am J Orthod Dentofacial Orthop 1991;99:564-6. 7. Karlsson I, Bondemark L. Intraoral maxillary molar distalization. Angle Orthod 2006:76:923-9. 8. Keles A, Erverdi N, Sezen S. Bodily distalization of molars with absolute anchorage. Angle Orthod 2002;73:471-82. 9. Byloff FK, Kärcher H, Clar E, Stoff F. An implant to eliminate anchorage loss during molar distalization: a case report involving the Graz implant-supported pendulum. Int J Adult Orthod Orthognath Surg 2000;15:129-37.
10. Kircelli BH, Pektas ZO, Kircelli C. Maxillary molar distalization with a bone-anchored pendulum appliance. Angle Orthod 2006;76:650-9. 11. Oncag G, Akyalçın S, Arıkan F. The effectiveness of a single osteointegrated implant combined with pendulum springs for molar distalization. Am J Orthod Dentofacial Orthop 2007;131:277-84. 12. Sugawara J, Kanzaki R, Takahashi I, Nagasaka H, Nanda R. Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system. Am J Orthod Dentofacial Orthop 2006;129:723-33. 13. Kyung SH, Hong SG, Park YC. Distalization of maxillary molars with midpalatal miniscrew. J Clin Orthod 2003:37;22-6. 14. Hwang HS, Kim WS, McNamara JA Jr. European-American adults with normal occlusions well-balanced faces. Angle Orthod 2002;72:72-80. 15. Wehrbein H, Merz BR, Diedrich P. Palatal bone support for orthodontic implant anchorage—a clinical and radiological study. Eur J Orthod 1999;21:65-70. 16. Lang J. Clinical anatomy of the nose, nasal cavity and paranasal sinuses. New York: Thieme; 1989. p.103. 17. Kim HJ, Yun HS, Park HD, Kim DH, Park YC. Soft-tissue and cortical-bone thickness at orthodontic implant sites. Am J Orthod Dentofacial Orthop 2006;130:177-82.