- Email: [email protected]
The bone-anchored Pendulum appliance
36
The bone-anchored Pendulum appliance Beyza Hancıoglu Kircelli and Zafer Ozgur Pektas
INTRODUCTION The original Pendulum appliance had two main parts: the active TMA springs, delivering a light and continuous distal force to the maxillary first molars, and a large palatal acrylic resin Nance button that provided anchor age through attachment to teeth (see Fig. 2.8). The intramaxillary appli ance generated a distal and intrusive force to the maxillary molars and a reciprocal mesial and extrusive force to the anchoring premolars. The active TMA springs produced a broad swinging arch or pendulum type of force from the midpalate to the molars. The major concern regarding the Pendulum appliance is the anchorage loss of the anterior teeth in terms of forward movement (see Chapter 2). With forces applied on the molars, the reactive forces are received by the anchoring premolars and mucosa of the palatal vault. Therefore, the reac tive forces emerging on the anterior anchorage segment create a mesial tipping and extrusion of the premolars, and consequently incisor proclina tion and increase of the overjet. This effect is in contradiction to the goals of treatment of Class II malocclusion at most times, particularly where there is already an increased overjet or crowding of the maxillary dental arch. In order to overcome the problem of anterior anchorage loss, in 2006, Kircelli et al.1 modified the original Pendulum appliance by using mini screw implants (MIs) under the Nance button to create the the boneanchored Pendulum appliance (BAPA). A further modification combined the pendulum springs with palatal osseointegrated implants.2
CLINICAL APPLICATION The BAPA is a modified Pendulum appliance that is anchored to the palatal bone by MIs, preferably two, which are located under an acrylic resin Nance button. Pendulum springs of TMA wire (0.032 inch) are fabricated and activated in the same way as with the original Pendulum appliance. Two MIs (diameter, 2.0 mm; fixation screw length, 8 mm; IMF inter maxillary, Stryker, Leibinger, Germany) are inserted in the paramedian region of the anterior median palatal suture, 7–8 mm posterior to the incisive foramen and 3–4 mm lateral to the median line (see Fig. 36.2B, below). After soft tissue healing, impressions and casts are obtained. The MI heads are blocked out with wax on the cast, and the appliance is con structed according to Hilgers’ descriptions,3 excluding the auxiliary wires for dental anchorage. The appliance is checked in the mouth and the springs are activated parallel to the median palatal suture. The acrylic resin plate is connected to the MI heads using cold-curing, methyl methacrylatefree acrylic resin (Ufi Gel hard, Voco, Cuxhaven, Germany). Finally, the activated TMA springs (Ormco Corp, Glendora, CA, USA) are inserted into the lingual sheaths on the first molar bands (Fig. 36.1). Patients should be instructed carefully on oral hygiene and regular use of a mouthwash. The soft tissues are checked at each appointment, when the springs can also be reactivated if necessary.
REMOVING THE APPLIANCE The only difficulty that may be experienced in removing the BAPA is in detaching the acrylic resin plate from the MI head. A carbide bur with an
186
Fig. 36.1 The boneanchored Pendulum appliance in place.
aerotor under copious irrigation can be used. To facilitate this detachment, it is suggested that the resin plate is made no thicker than 2 mm over the MI head and the grooves on the top of the MIs are filled with a thin layer of wax. Alternatively, the Nance button can be fabricated without acrylic resin coverage of the MIs.4
CASE PRESENTATION A 12-year-old girl was referred with crowding of her teeth (Fig. 36.2). She had a skeletal Class I relationship (ANB angle, 2.1°) with dental Class II molar and canine relationships. She had an average growth pattern, with a Frankfort–mandibular plane angle of 27° and a sella/nasion–mandibular plane angle of 34°. She had 7 mm crowding in the maxillary arch and mild crowding in the mandibular arch. The maxillary canines were erupted buccally. The maxillary dental midline was shifted 2 mm to the right side. She had a normal overjet and overbite of 3.7 mm and 2.3 mm, respec tively. Maxillary and mandibular incisor inclinations were within the normal limits. Her profile was well balanced (lower lip to E-plane, 0.9 mm). The treatment plan was to distalize the first molars in the maxillary arch to achieve a Class I molar and canine relationship and to gain space for the alignment of the maxillary crowding and correction of the midline shift. In the mandibular arch, proximal stripping of the mandibular incisors was planned to gain the appropriate space needed for alignment of the mild crowding. Since the maxillary and mandibular incisors presented normal inclinations and the profile was well balanced, molar distalization would be undertaken using the BAPA (Fig. 36.2C). Maxillary molar distalization took 7 months to achieve a super-Class I molar relationship on both sides. In addition, the first and second premolars drifted distally to a Class I relationship. Because of this spontaneous distalization, partial alignment of the maxillary anterior crowding was achieved and even the midline discrepancy was spontaneously corrected (Fig. 36.2D,E). The second phase of treatment used full fixed appliances. During the uprighting process of the distally tipped molars and premolars, the BAPA was left in place to reinforce anchorage of the newly distalized molars. Overall treatment lasted approximately 22 months. After finishing, flat tened and dead soft 8-braided wire (Bond-a-Braid, Reliance Orthodontics, Itasca, IL, USA) was bonded to each tooth from canine to canine in both maxillary and mandibular arches for retention purposes (Fig. 36.2F,G). In
The bone-anchored Pendulum appliance
A
B
C
D
E
F
187
G
Fig. 36.2 Treatment of a 12-year-old girl with skeletal Class I relationships with dental Class II molar and canine relationship. (A,B) Pretreatment. (C) The bone-anchored Pendulum appliance in place. (D,E) After maxillary molar distalization, with distal drift of the premolars along with the first molars to a Class I relationship and the spontaneous alignment of the canines. (F,G) Post-treatment.
addition, for the first 6 months after debonding, transparent thermoplastic vacuum-molded retainers were recommended to be worn at night.
DISCUSSION The BAPA seems to be an effective intraoral maxillary molar distalization appliance. Kircelli et al.1 reported a mean maxillary first molar distaliza tion of 6.4 mm in approximately 7 months, with the second and first premolars drifted distally a mean of 5.4 and 3.8 mm, respectively. This simplifies and shortens treatment. Anterior crowding can be, at least par tially, corrected spontaneously during molar distalization, with an average of 13.9 and 6.2 mm of space gain after molar distalization in the total maxillary dental arch and in the anterior segment, respectively.1 As the BAPA is identical to the original Pendulum appliance apart from the method of anchorage, maxillary molar tipping could be expected to occur. Studies using MI-supported Pendulum appliances show various degrees of molar tipping, from 9.1 to 14.4°.1,2,4,5 A systematic review has evaluated the effectiveness of the distalization of molars with distalizers supported by temporary skeletal anchorage compared with tooth-borne anchorage.6 Greater molar distal tipping was seen with the devices supported by tem porary skeletal anchorage, which the authors suggested might be a conse quence of the greater pressure exerted on the molars in this method. We also consider that the increased tipping is linked to the greater amount of distalization achieved. This is supported by studies showing more distal tipping with a greater molar distalization.6,7 This link could have two causes. First, clinicians may prefer to use devices supported by temporary skeletal anchorage for patients who need more extensive molar distaliza tion. Second, anchorage loss, through space opening between the diverging molars and the second premolars, in a tooth-supported system may occur earlier in distalization and so the process would be terminated earlier, thus limiting the amount of molar tipping. A comparison of the original Pen dulum appliance with the BAPA in a group of 39 patients indicated that 4.8 mm of molar distalization and 9.1° of molar tipping was achieved in 6.8 months with BAPA therapy, while 2.7 mm of molar distalization and 5.3° of molar tipping was evident after 5.1 months of treatment with the tooth-anchored appliance (Table 36.1). This supports the idea that the greater distal movement of maxillary molars may cause more distal tipping of their crowns.
Table 36.1 Comparison of treatment changes between the boneanchored Pendulum appliance and the conventional Pendulum appliance Variables
Bone anchored (mean ± SD)
Conventional (mean ± SD)
No. in group
22
17
Age of patients (years)
13.6 ± 2.1
13.6 ± 2.0
Distalization time (months)
6.8 ± 1.7
5.1 ± 0.9
0.010
1st molar (mm)
4.8 ± 1.8 distal mv.
2.7 ± 1.7 distal mv.
0.025
1st molar (°)
9.1 ± 4.6 distal tip.
5.3 ± 3.8 distal tip.
0.008
2nd premolar (mm)
4.1 ± 2.1 distal mv.
2.3 ± 2.1 mesial mv.
0.000
2nd premolar (°)
9.9 ± 5.2 distal tip.
3.8 ± 2.7 mesial tip.
0.000
1st incisor (mm)
1.2 ± 1.7 retrusion
0.1 ± 1.7 protrusion
0.035
1st incisor (°)
1.7 ± 2.9 retroclination
0.9 ± 2.4 proclination
0.034
p valuea
mv, movement; tip, tipping; SD, standard deviation; BAPA, bone-anchored Pendulum appliance; CPA, conventional Pendulum appliance. a Significance from independent t-test. Source: from Polat-Ozsoy et al., 2008.5
Distalization with tipping is significant because some of the space created can be lost during molar uprighting when full fixed therapy is initi ated. However, the BAPA can be left in place immediately after distaliza tion and it will then be able to maintain molar position when a continuous archwire is applied to upright the molars. Thus, molar position can be maintained when leveling and retracting the first premolars and canines. This concept of “active anchorage” is helpful to cope with the anchorage concerns when distalizing maxillary molars.8 Overcorrection of the molar relationships could also be used to support molar anchorage during full fixed therapy, particularly if distal tipping exists. In this context, the BAPA can be used to move maxillary molars to a super-Class I relationship to overcome the anchorage loss that takes place during the leveling and anterior teeth retraction phase of treatment. Some skeletal and soft tissue effects have been observed with the BAPA; the cant of the palatal plane remained unchanged but the mandibular plane rotated by 0.98° in a clockwise direction after molar distalization.1
188 SECTION VII: MINISCREW IMPLANTS FOR THE TREATMENT OF CLASS II MALOCCLUSION
Clockwise rotation can be attributed to the fact that maxillary molars move distally into the wedge of occlusion as well as to cusp interferences. Although clinically insignificant, point A moved anteriorly by 0.6 mm. This might occur through a modeling process with reciprocal forces acting on the anterior plate causing bone apposition at the A-point. Further studies should be conducted to test this hypothesis. No significant differences were observed regarding the upper and lower lip positions relative to the esthetic line after molar distalization with the BAPA.1
COMPREHENSIVE TREATMENT OUTCOMES Cephalometric outcomes following distalization of the maxillary molars using the BAPA have been assessed.9 In the first distalization stage, the maxillary first molars moved distally 4.6 mm and the second and first premolars drifted distally 2.9 and 2.2 mm, respectively. At the end of the comprehensive treatment, statistically significant mesial movement of the molars (2.8 mm) and the second premolars (1.7 mm) was observed. The maxillary first molars exhibited significant distal tipping (13.0°) during the first phase of treatment, but they were effectively uprighted in the second phase with fixed orthodontic appliances. Approximately 61% of the molar distalization obtained in the first phase of treatment was lost during the second phase of treatment; however, the Class I molar relation ship was maintained. The mesial movement detected at the end of the comprehensive treatment in this study could not be totally attributed to relapse of distalization since continuing eruption of the maxillary molars in a forward and downward direction was taking place and this may have contributed to the mesial molar movement.9 In patients with growth potential, the mandible outgrows the maxilla and thus the mandibular first molars move anteriorly in most patients. Consequently, despite the mesialization of the maxillary molars, mainte nance of the new Class I molar relationship at the end of fixed appliance therapy is probably achieved by dentoalveolar compensation and contin ued normal anterior mandibular growth.
CONCLUSIONS The BAPA presents an efficient, convenient and cost-effective Pendulum appliance modification. It is a reasonable choice for non-compliant
treatment of Class II patients presenting with a horizontal or average growth pattern in routine clinical practice. It is particularly useful for borderline situations where there is usually a need to extract the maxillary premolars. The major drawback of the appliance is the significant distal tipping of the molar crowns, which occurs along with molar distalization. In addition, minor mandibular posterior rotation should be taken into account when using the BAPA. When deciding an individual treatment plan, it must be considered that more than half of the amount of the new maxillary position achieved by intraoral molar distalization will be lost. It is obvious, therefore, that the mandibular growth pattern is very important to maintain the achieved Class I molar relationship, and patients who present a vertical growth pattern may not be good candidates for treatment by intraoral molar dis talization with the BAPA.
REFERENCES 1. Kircelli BH, Pektaş ZO, Kircelli C. Maxillary molar distalization with a bone-anchored pendulum appliance. Angle Orthod 2006;76:650–9. 2. Oncag G, Seckin O, Dincer B, et al. Osseointegrated implants with pendulum springs for maxillary molar distalization: a cephalometric study. Am J Orthod Dentofacial Orthop 2007;131:16–26. 3. Hilgers JJ. The pendulum appliance for Class II non-compliance therapy. J Clin Orthod 1992;26:706–14. 4. Escobar SA, Tellez PA, Moncada CA, et al. Distalization of maxillary molars with the bone-supported pendulum: a clinical study. Am J Orthod Dentofacial Orthop 2007;131:545–9. 5. Polat-Ozsoy O, Kircelli BH, Arman-Ozcirpici A, et al. Pendulum appliances with 2 anchorage designs: conventional anchorage vs bone anchorage. Am J Orthod Dento facial Orthop 2008;133:339. 6. Fudalej P, Antoszewska J. Are orthodontic distalizers reinforced with the temporary skeletal anchorage devices effective? Am J Orthod Dentofacial Orthop 2011;139: 722–9. 7. Antonarakis GS, Kiliaridis S. Maxillary molar distalization with noncompliance intramaxillary appliances in Class II malocclusion. Angle Orthod 2008;78:1133–40. 8. Byloff FK, Kärcher H, Clar E, et al. An implant to eliminate anchorage loss during molar distalization: a case report involving the Graz implant-supported pendulum. Int J Adult Orthodon Orthognath Surg 2000;15:129–37. 9. Kircelli BH, Pektas ZO, Karan S, et al. Evaluation of the changes associated with bone-anchored pendulum appliance after the completion of comprehensive orthodon tic treatment. Turkish J Orthod 2008;21:13–24.
The bone-anchored Pendulum appliance Beyza Hancıoglu Kircelli and Zafer Ozgur Pektas
INTRODUCTION The original Pendulum appliance had two main parts: the active TMA springs, delivering a light and continuous distal force to the maxillary first molars, and a large palatal acrylic resin Nance button that provided anchor age through attachment to teeth (see Fig. 2.8). The intramaxillary appli ance generated a distal and intrusive force to the maxillary molars and a reciprocal mesial and extrusive force to the anchoring premolars. The active TMA springs produced a broad swinging arch or pendulum type of force from the midpalate to the molars. The major concern regarding the Pendulum appliance is the anchorage loss of the anterior teeth in terms of forward movement (see Chapter 2). With forces applied on the molars, the reactive forces are received by the anchoring premolars and mucosa of the palatal vault. Therefore, the reac tive forces emerging on the anterior anchorage segment create a mesial tipping and extrusion of the premolars, and consequently incisor proclina tion and increase of the overjet. This effect is in contradiction to the goals of treatment of Class II malocclusion at most times, particularly where there is already an increased overjet or crowding of the maxillary dental arch. In order to overcome the problem of anterior anchorage loss, in 2006, Kircelli et al.1 modified the original Pendulum appliance by using mini screw implants (MIs) under the Nance button to create the the boneanchored Pendulum appliance (BAPA). A further modification combined the pendulum springs with palatal osseointegrated implants.2
CLINICAL APPLICATION The BAPA is a modified Pendulum appliance that is anchored to the palatal bone by MIs, preferably two, which are located under an acrylic resin Nance button. Pendulum springs of TMA wire (0.032 inch) are fabricated and activated in the same way as with the original Pendulum appliance. Two MIs (diameter, 2.0 mm; fixation screw length, 8 mm; IMF inter maxillary, Stryker, Leibinger, Germany) are inserted in the paramedian region of the anterior median palatal suture, 7–8 mm posterior to the incisive foramen and 3–4 mm lateral to the median line (see Fig. 36.2B, below). After soft tissue healing, impressions and casts are obtained. The MI heads are blocked out with wax on the cast, and the appliance is con structed according to Hilgers’ descriptions,3 excluding the auxiliary wires for dental anchorage. The appliance is checked in the mouth and the springs are activated parallel to the median palatal suture. The acrylic resin plate is connected to the MI heads using cold-curing, methyl methacrylatefree acrylic resin (Ufi Gel hard, Voco, Cuxhaven, Germany). Finally, the activated TMA springs (Ormco Corp, Glendora, CA, USA) are inserted into the lingual sheaths on the first molar bands (Fig. 36.1). Patients should be instructed carefully on oral hygiene and regular use of a mouthwash. The soft tissues are checked at each appointment, when the springs can also be reactivated if necessary.
REMOVING THE APPLIANCE The only difficulty that may be experienced in removing the BAPA is in detaching the acrylic resin plate from the MI head. A carbide bur with an
186
Fig. 36.1 The boneanchored Pendulum appliance in place.
aerotor under copious irrigation can be used. To facilitate this detachment, it is suggested that the resin plate is made no thicker than 2 mm over the MI head and the grooves on the top of the MIs are filled with a thin layer of wax. Alternatively, the Nance button can be fabricated without acrylic resin coverage of the MIs.4
CASE PRESENTATION A 12-year-old girl was referred with crowding of her teeth (Fig. 36.2). She had a skeletal Class I relationship (ANB angle, 2.1°) with dental Class II molar and canine relationships. She had an average growth pattern, with a Frankfort–mandibular plane angle of 27° and a sella/nasion–mandibular plane angle of 34°. She had 7 mm crowding in the maxillary arch and mild crowding in the mandibular arch. The maxillary canines were erupted buccally. The maxillary dental midline was shifted 2 mm to the right side. She had a normal overjet and overbite of 3.7 mm and 2.3 mm, respec tively. Maxillary and mandibular incisor inclinations were within the normal limits. Her profile was well balanced (lower lip to E-plane, 0.9 mm). The treatment plan was to distalize the first molars in the maxillary arch to achieve a Class I molar and canine relationship and to gain space for the alignment of the maxillary crowding and correction of the midline shift. In the mandibular arch, proximal stripping of the mandibular incisors was planned to gain the appropriate space needed for alignment of the mild crowding. Since the maxillary and mandibular incisors presented normal inclinations and the profile was well balanced, molar distalization would be undertaken using the BAPA (Fig. 36.2C). Maxillary molar distalization took 7 months to achieve a super-Class I molar relationship on both sides. In addition, the first and second premolars drifted distally to a Class I relationship. Because of this spontaneous distalization, partial alignment of the maxillary anterior crowding was achieved and even the midline discrepancy was spontaneously corrected (Fig. 36.2D,E). The second phase of treatment used full fixed appliances. During the uprighting process of the distally tipped molars and premolars, the BAPA was left in place to reinforce anchorage of the newly distalized molars. Overall treatment lasted approximately 22 months. After finishing, flat tened and dead soft 8-braided wire (Bond-a-Braid, Reliance Orthodontics, Itasca, IL, USA) was bonded to each tooth from canine to canine in both maxillary and mandibular arches for retention purposes (Fig. 36.2F,G). In
The bone-anchored Pendulum appliance
A
B
C
D
E
F
187
G
Fig. 36.2 Treatment of a 12-year-old girl with skeletal Class I relationships with dental Class II molar and canine relationship. (A,B) Pretreatment. (C) The bone-anchored Pendulum appliance in place. (D,E) After maxillary molar distalization, with distal drift of the premolars along with the first molars to a Class I relationship and the spontaneous alignment of the canines. (F,G) Post-treatment.
addition, for the first 6 months after debonding, transparent thermoplastic vacuum-molded retainers were recommended to be worn at night.
DISCUSSION The BAPA seems to be an effective intraoral maxillary molar distalization appliance. Kircelli et al.1 reported a mean maxillary first molar distaliza tion of 6.4 mm in approximately 7 months, with the second and first premolars drifted distally a mean of 5.4 and 3.8 mm, respectively. This simplifies and shortens treatment. Anterior crowding can be, at least par tially, corrected spontaneously during molar distalization, with an average of 13.9 and 6.2 mm of space gain after molar distalization in the total maxillary dental arch and in the anterior segment, respectively.1 As the BAPA is identical to the original Pendulum appliance apart from the method of anchorage, maxillary molar tipping could be expected to occur. Studies using MI-supported Pendulum appliances show various degrees of molar tipping, from 9.1 to 14.4°.1,2,4,5 A systematic review has evaluated the effectiveness of the distalization of molars with distalizers supported by temporary skeletal anchorage compared with tooth-borne anchorage.6 Greater molar distal tipping was seen with the devices supported by tem porary skeletal anchorage, which the authors suggested might be a conse quence of the greater pressure exerted on the molars in this method. We also consider that the increased tipping is linked to the greater amount of distalization achieved. This is supported by studies showing more distal tipping with a greater molar distalization.6,7 This link could have two causes. First, clinicians may prefer to use devices supported by temporary skeletal anchorage for patients who need more extensive molar distaliza tion. Second, anchorage loss, through space opening between the diverging molars and the second premolars, in a tooth-supported system may occur earlier in distalization and so the process would be terminated earlier, thus limiting the amount of molar tipping. A comparison of the original Pen dulum appliance with the BAPA in a group of 39 patients indicated that 4.8 mm of molar distalization and 9.1° of molar tipping was achieved in 6.8 months with BAPA therapy, while 2.7 mm of molar distalization and 5.3° of molar tipping was evident after 5.1 months of treatment with the tooth-anchored appliance (Table 36.1). This supports the idea that the greater distal movement of maxillary molars may cause more distal tipping of their crowns.
Table 36.1 Comparison of treatment changes between the boneanchored Pendulum appliance and the conventional Pendulum appliance Variables
Bone anchored (mean ± SD)
Conventional (mean ± SD)
No. in group
22
17
Age of patients (years)
13.6 ± 2.1
13.6 ± 2.0
Distalization time (months)
6.8 ± 1.7
5.1 ± 0.9
0.010
1st molar (mm)
4.8 ± 1.8 distal mv.
2.7 ± 1.7 distal mv.
0.025
1st molar (°)
9.1 ± 4.6 distal tip.
5.3 ± 3.8 distal tip.
0.008
2nd premolar (mm)
4.1 ± 2.1 distal mv.
2.3 ± 2.1 mesial mv.
0.000
2nd premolar (°)
9.9 ± 5.2 distal tip.
3.8 ± 2.7 mesial tip.
0.000
1st incisor (mm)
1.2 ± 1.7 retrusion
0.1 ± 1.7 protrusion
0.035
1st incisor (°)
1.7 ± 2.9 retroclination
0.9 ± 2.4 proclination
0.034
p valuea
mv, movement; tip, tipping; SD, standard deviation; BAPA, bone-anchored Pendulum appliance; CPA, conventional Pendulum appliance. a Significance from independent t-test. Source: from Polat-Ozsoy et al., 2008.5
Distalization with tipping is significant because some of the space created can be lost during molar uprighting when full fixed therapy is initi ated. However, the BAPA can be left in place immediately after distaliza tion and it will then be able to maintain molar position when a continuous archwire is applied to upright the molars. Thus, molar position can be maintained when leveling and retracting the first premolars and canines. This concept of “active anchorage” is helpful to cope with the anchorage concerns when distalizing maxillary molars.8 Overcorrection of the molar relationships could also be used to support molar anchorage during full fixed therapy, particularly if distal tipping exists. In this context, the BAPA can be used to move maxillary molars to a super-Class I relationship to overcome the anchorage loss that takes place during the leveling and anterior teeth retraction phase of treatment. Some skeletal and soft tissue effects have been observed with the BAPA; the cant of the palatal plane remained unchanged but the mandibular plane rotated by 0.98° in a clockwise direction after molar distalization.1
188 SECTION VII: MINISCREW IMPLANTS FOR THE TREATMENT OF CLASS II MALOCCLUSION
Clockwise rotation can be attributed to the fact that maxillary molars move distally into the wedge of occlusion as well as to cusp interferences. Although clinically insignificant, point A moved anteriorly by 0.6 mm. This might occur through a modeling process with reciprocal forces acting on the anterior plate causing bone apposition at the A-point. Further studies should be conducted to test this hypothesis. No significant differences were observed regarding the upper and lower lip positions relative to the esthetic line after molar distalization with the BAPA.1
COMPREHENSIVE TREATMENT OUTCOMES Cephalometric outcomes following distalization of the maxillary molars using the BAPA have been assessed.9 In the first distalization stage, the maxillary first molars moved distally 4.6 mm and the second and first premolars drifted distally 2.9 and 2.2 mm, respectively. At the end of the comprehensive treatment, statistically significant mesial movement of the molars (2.8 mm) and the second premolars (1.7 mm) was observed. The maxillary first molars exhibited significant distal tipping (13.0°) during the first phase of treatment, but they were effectively uprighted in the second phase with fixed orthodontic appliances. Approximately 61% of the molar distalization obtained in the first phase of treatment was lost during the second phase of treatment; however, the Class I molar relation ship was maintained. The mesial movement detected at the end of the comprehensive treatment in this study could not be totally attributed to relapse of distalization since continuing eruption of the maxillary molars in a forward and downward direction was taking place and this may have contributed to the mesial molar movement.9 In patients with growth potential, the mandible outgrows the maxilla and thus the mandibular first molars move anteriorly in most patients. Consequently, despite the mesialization of the maxillary molars, mainte nance of the new Class I molar relationship at the end of fixed appliance therapy is probably achieved by dentoalveolar compensation and contin ued normal anterior mandibular growth.
CONCLUSIONS The BAPA presents an efficient, convenient and cost-effective Pendulum appliance modification. It is a reasonable choice for non-compliant
treatment of Class II patients presenting with a horizontal or average growth pattern in routine clinical practice. It is particularly useful for borderline situations where there is usually a need to extract the maxillary premolars. The major drawback of the appliance is the significant distal tipping of the molar crowns, which occurs along with molar distalization. In addition, minor mandibular posterior rotation should be taken into account when using the BAPA. When deciding an individual treatment plan, it must be considered that more than half of the amount of the new maxillary position achieved by intraoral molar distalization will be lost. It is obvious, therefore, that the mandibular growth pattern is very important to maintain the achieved Class I molar relationship, and patients who present a vertical growth pattern may not be good candidates for treatment by intraoral molar dis talization with the BAPA.
REFERENCES 1. Kircelli BH, Pektaş ZO, Kircelli C. Maxillary molar distalization with a bone-anchored pendulum appliance. Angle Orthod 2006;76:650–9. 2. Oncag G, Seckin O, Dincer B, et al. Osseointegrated implants with pendulum springs for maxillary molar distalization: a cephalometric study. Am J Orthod Dentofacial Orthop 2007;131:16–26. 3. Hilgers JJ. The pendulum appliance for Class II non-compliance therapy. J Clin Orthod 1992;26:706–14. 4. Escobar SA, Tellez PA, Moncada CA, et al. Distalization of maxillary molars with the bone-supported pendulum: a clinical study. Am J Orthod Dentofacial Orthop 2007;131:545–9. 5. Polat-Ozsoy O, Kircelli BH, Arman-Ozcirpici A, et al. Pendulum appliances with 2 anchorage designs: conventional anchorage vs bone anchorage. Am J Orthod Dento facial Orthop 2008;133:339. 6. Fudalej P, Antoszewska J. Are orthodontic distalizers reinforced with the temporary skeletal anchorage devices effective? Am J Orthod Dentofacial Orthop 2011;139: 722–9. 7. Antonarakis GS, Kiliaridis S. Maxillary molar distalization with noncompliance intramaxillary appliances in Class II malocclusion. Angle Orthod 2008;78:1133–40. 8. Byloff FK, Kärcher H, Clar E, et al. An implant to eliminate anchorage loss during molar distalization: a case report involving the Graz implant-supported pendulum. Int J Adult Orthodon Orthognath Surg 2000;15:129–37. 9. Kircelli BH, Pektas ZO, Karan S, et al. Evaluation of the changes associated with bone-anchored pendulum appliance after the completion of comprehensive orthodon tic treatment. Turkish J Orthod 2008;21:13–24.