REMOVABLE TWIN BLOCK FUNCTIONAL APPLIANCE IN THE TREATMENT ...

Studia Universitatis "Vasile Goldi", Seria tiinele Vieii Vol. 23, issue 2, 2013, pp. 121-124

? 2013 Vasile Goldis University Press (studiauniversitatis.ro)

REMOVABLE TWIN BLOCK FUNCTIONAL APPLIANCE IN THE TREATMENT OF CLASS II DIVISION 2 MALOCCLUSION

Delia Elena DARAGIU, Doina Lucia GHERGIC "Titu Maiorescu" University, Faculty of Dental Medicine

ABSTRACT. This case report shows the treatment effects of class II division 2 malocclusion in a 10 years old boy with twin block functional appliance. The treatment consists of two stages: First stage- treatment with removable twin block functional appliance followed later by second stage: fixed appliances to correct the position, the torque of upper central incisors.

Keywords: class II division 2 malocclusion, class II skeletal base, functional appliance, Twin Block

INTRODUCTION Class II division 2 malocclusion presents difficulty

in the provision of stable results (Selwyn Barnett, 1991). Correction of the antero-posterior, transvers and vertical discrepancies are important for a successful treatment.

Selwyn Barnett (1991, 1996) demonstrated the need for expansion and limited proclination of lower incisors during treatment and recommended early treatment in the mixed dentition using removable appliances to begin buccal segment correction and reduce the overbite. Later, in a second phase, upper and lower fixed appliances are placed, usually with no extractions.

Treatment of a class II division 2 malocclusion of an actively growing patient consists of proclining the upper incisors by using an upper removable appliance, trying to convert it in a class II division 1 malocclusion. This is then followed by functional treatment in order to correct sagittal discrepancy.

The twin block developed by William Clark is popular and clinically successful appliance. It is worn 24/24 hours, and because of increased daily wear and patient cooperation the correction of sagittal discrepancy is achieved in approximately 9 months of wear.

Studies comparing treated cases with twin block and control groups (Trenmouth, 2000; Lund and Sandler 1998, Mills and McCullouch, 1998) showed small, but significant increases in mandibular length. The majority of overjet correction occurs because of dentoalveolar compensations.

Studies comparing Twin Block with other functional appliances showed that Twin Block is the best in producing sagittal modifications. These changes are due to skeletal mandibular changes, dentoalveolar changes and normal growth changes.

This paper shows that a modified Twin Block appliance can be used successfully to treat a Class II division 2 malocclusion from the beginning, thus avoiding the initial stage of upper removable appliance to align the upper labial segment. Sagittal correction of the malocclusion and the correction of the retroclined upper incisors are done together, at the same time.

Patient selection and bite registration: The patient treated with modified Twin Block has a

class II division 2 malocclusion on a moderate class II skeletal base with an ANB of 6-9 degrees. The buccal segment relationship should ideally be at least half of unit Class II and the patient has potential for further facial growth. The axial inclination of the upper incisor is corrected initially by labial tipping and this corrected inclination is maintained during further correction of the malocclusion. (Dyer, McKeown, Sandler, 2001)

The bite registration is taken with the buccal segment relationship in an overcorrected relationship; this may result in an edge to edge incisor relationship. It is important to have sufficient height of the blocks so the patient is comfortable in posturing forward the mandible instead of closing centric occlusion and we should have 7-8 mm of separation in the buccal segments and no incisal interference as the upper labial segment proclines. The appliance design:

Both appliances are a modified Twin Block appliance (Clark 1982). They have Stahl clasps on the buccal segments, and ball ended clasps on the lower labial segment. The upper appliance contains a midline expansion screw and two "S" springs on upper central incisors and no vestibular arch. The lower appliance also contains a midline expansion screw and a vestibular arch. The inclined planes are constructed at 70 degrees to the occlusal plane. Advancement, if required, is carried out by the addition of small acrylic tablets to the upper block. Case report:

A 10 years old boy was referred by his dentist. He presented with a class II division 2 incisal relationship on a moderate class II skeletal base, with mandibular retrognathia. He is in mixed dentition. The upper central incisors are retroclined and the upper lateral incisors are proclined. There was mild crowding in the labial segments, in occlusion the overbite was complete. The buccal segment relationship was half unit class II on the right side and full unit class II on the left side. The mandible shifts to the left side on closure (Figure 1, 2).

*Correspondence: Delia Elena Daragiu, "Titu Maiorescu" University, Faculty of Dental Medicine Article received: February 2013; published: May 2013

Daragiu D. E., Ghergic D. L.

Fig.1 Before treatment

Fig. 3 Black line- before treatment, Red line- after treatment with Twin Block Superimopsition on SN line

Fig. 2 Before treatment

The cephalometric tracing confirmed that the patient had a moderate Class II skeletal base relationship with an ANB value of 7.5 degrees, the mandibular plane angle was 23.5 degrees. The upper incisors were retroclined at 93 degrees, incisor mandibular plane angle 94.5 degrees, inter-incisal angle was 146 degrees. (Figure 3)

Treatment involved correction of class II skeletal relationship with a Twin Block appliance and simultaneously proclining the upper labial segment.

Twin block appliances were fitted and instructions given to turn the midline screws both once a week. The buccal blocks were trimmed posteriorly to allow buccal eruption and reactivate anteriorly to continue anteroposterior correction.

After a year of treatment the lateral cephlogram indicated correction of the mandibular position (Figure 3 and 5), the molar relationship was corrected, the overbite was reduced, the interjaw relationship was corrected and confirmed by the superimpositions (Figure 3,4,5) and lateral cephalograms analysis before and after Twin Block therapy (Table 1 ).

122

Fig.4 Superimposition on the maxilla, black line- before treatment, red line- after treatment with Twin Block

Fig. 5 Superimposition on mandible- black line-before treatment, red line-after treatment with Twin Block

Aesthetic improvements were observed with correction of the convex profile, the reduction of the mentolabial sulcus, the protrusion of the upper lip (Figure 3, 5).

Studia Universitatis "Vasile Goldi", Seria tiinele Vieii Vol. 23, issue 2, 2013, pp.121-124

? 2013 Vasile Goldis University Press (studiauniversitatis.ro)

RESULTS AND DICUSSIONS Mandibular base length increased by 6.5 mm ,

which was measured from Ar-Pog, SNA reduced with 0.50, the SNB increased by 2 0, ANB decreased by 2.50, anterior facial height (AFH) increased by 6mm, and posterior facial height (PFH) increased by 3 mm.

The patient was instructed to turn the maxillary and mandibular midline screws one turn per week. The treatment duration lasted for 12 month. The pre and post treatment lateral cephalometric radiograph were obtained in centric occlusion under standard conditions

Removable Twin Block functional appliance in the treatment of class II division 2 malocclusion

and traced manually on matte acetate paper using a 0.5 mm pencil. The angular parameters measured were SNA, SNB, ANB and upper central incisor to palatal plane (NL), lower incisor to mandibular plane (IMPA). The linear parameters included mandibular length, anterior facial height and posterior facial height.

Class I molar relationship was achieved partly because of the mandibular growth and partly because of the mesial movement of the mandibular first molar, and slight distal movement of upper molars. (Figure 6)

Fig. 6 After treatment with Twin Block

Antero-posterior correction was achieved after 1 year full time wear, the ANB reduced by 2.5 degrees. Superimpositions revealed mandibular changes in

Studia Universitatis "Vasile Goldi", Seria tiinele Vieii Vol. 23, issue 2, 2013, pp. 121-124 ? 2013 Vasile Goldis University Press (studiauniversitatis.ro)

horizontal and vertical directions, with increase in anterior face height (AFH) of 6 mm and increase in

123

Daragiu D. E., Ghergic D. L.

posterior facial height (PFH) of 3 mm, the SNB angle increased with 2 degrees.

Following treatment the patient's facial appearance improved with the mandible appearing less retrognathic and the lower anterior face height increased.

By using Twin Block functional removable appliances in treating class II division 2 malocclusion treatment time is reduced significantly by eliminating a pre-functional phase of treatment. The advancement of upper labial segment occurs simultaneously with the sagittal correction.

Pre-treatment and post-treatment cephalometric readings

Variable

Pre-treatment TB

Post treatment TB

Inter-incisal angle

1460

1380

FMA

24.50

240

SNA

76.50

760

SNB

690

710

ANB

7.50

50

1/-NL

930

970

AFH

54 mm

60 mm

PFH

38 mm

41 mm

IF

0.70

0.68

ML-NL

23.50

250

Ar-A

83 mm

85.5 mm

Ar-Me

90.5 mm

97.5 mm

ArA-ArMe

7.5 mm

12 mm

ArGo

38 mm

40 mm

Ar-B

86 mm

92 mm

Ar-Pg

92 mm

98.5 mm

Go-Me

63 mm

68.5 mm

Wits AO-BO

+4 mm

0.5 mm

Occlusal plane angle

11.5 mm

14.50

IMPA

94.50

1010

Table 1

Changes 80 0.50 0.50 20 2.50 40

6 mm 3 mm 0.02 1.50 2.5 mm 7 mm 4.5 mm 2 mm 6 mm 6.5 mm 5.5 mm 3.5 mm

30 6.50

CONCLUSIONS Modification of Twin Block appliance to provide

proclination of the upper incisors, has eliminated the need of a phase of pre-functional upper appliance. This technique has proved to be efficient and effective in the treatment of Class II division 2 malocclusion.

ACKNOWLEDGMENTS This work was co-financed from the European

Social Fund through Sectorial Operational Programme Human Resources Development 2007-2013, project number POSDRU/ CPP107/DMI 1.5/S/77082, "Doctoral Scholarships for eco-economy and bioeconomic complex training to ensure the food and feed safety and security of anthropogenic ecosystems".

REFERENCES Clark, W.J., The twin block traction technique,

European Journal of Orthodontics, 4, 129-138, 1982 Dyer FMV, McKeown HF, Sandler PJ, The modified Twin Block Appliance in the treatment of class II division 2 malocclusions, Journal of Orthodontics, vol.28, 217-280, 2001 Illing H.M., Morris DO, Lee RT, A prospective evaluation of Bass, Bionator and Twin Block appliances, Part1-the hard tissues, European Journal of Orthodontics,20, 501-516, 1998 Lund DI, Sandler PJ, The effects of Twin Blocks: a prospective controlledstudy, American Journal

124

of Orthodontics and Dentofacial Orthopedics, 113, 104-110, 1998 Mills CM, McCullouch KJ, Treatment effects of the Twin Block appliance: a cephalometric study, American Journal of Orthodontics and Dentofacial Orthopedics, 114, 15-21, 1998 Selwyn Barnett BJ, Rationale of treatmentfor Class II division 2 malocclusion, British Journalof Orthodontics, 18, 173-181, 1991 Selwyn Barnet BJ, Class II division 2 malocclusion: a method of planning and treatment, British Journal of Orthodontics, 23, 29-36, 1996 Trenmouth MJ, Cephalometric evalution of the Twin Block appliance in the treatment of Class II division 1 malocclusionwith matched normative growth data, American Journal of Orthodontics and Dentofacial Orthopedics, 117, 54-59

Studia Universitatis "Vasile Goldi", Seria tiinele Vieii Vol. 23, issue 2, 2013, pp.121-124

? 2013 Vasile Goldis University Press (studiauniversitatis.ro)

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download