protrusor

1. PREMAXILLA PROTRUSOR
¹Turan Çağrı DOĞAN
¹:Dentist-Special Elif Andaç Oral and Dental Health Polyclinic –Ödemiş/İzmir/Turkey
INTRODUCTION:
The present appliance is patented by Turkish Patent Institute with patent number 2011/06195 on the authors name. It can be used
by orthodontic field of dentistry to treat all cases with retrusion on antero-posterior direction (Class I, Class II, Class III, openbite,
deepbite). While it protrudes the anterior portion of the upper jaw it takes support from lover jaw by Class III elastics(7), and it is fixed
in the mouth and does not extrude extra-orally. It is an appliance consisting of 2 separate pieces fixed on upper and lower jaws. It is
named as “Premaxilla Protrusor” in Latin by the inventor.
SCIENTIFIC BACKGROUND:
In 1975 Melsen, reported, in his work on human cadavers, that on maxilla the midline suture that has the shape of a line has three
morphological stages. This suture that is named as Midpalatal suture (11) is in the shape of a short ‘’Y’’ in the beginning, on the
second stage is wavier and on the third stage has a strong interdigitation that prevents separation of the suture without a fracture. He
also stated that until 13-15 years old the dimensional change on the palate is due to the growth at the suture and also apposition on
the back parts of the palate and at this time growth is completed but apposition continues for some more years. (Fig. 1).
The “Y” shape referred above has a big emphassis for this invention. Since, there is a suture that resembles the “Y “ letter named
“sutura incissiva” (1), just behind the frontal of the upper jaw, that is named as “premaxilla” between upper canine and lateral tooth,
bilaterally joining together at midpalatal suture (11)(Fig. 1-2).
This is a suture that is neglected, not paid enough attention, to tell the reality is a forgotten suture. But, on any maxillary
distalisation appliance (Distal Jet, Pendex, Pendilum, Keleş Slider, etc.) there is an adverse effect of pushing the frontal segment of the
maxilla forward. The reason of this unexplained side effect is the incisal suture (1). Growth can only be achieved on a bone with a
joint or a suture, it is difficult to achieve on a straight complete bone structure. The present invention converts the adverse effects of
the mentioned appliances, applying force to sutura incisiva (1). Unlike Reverse Headgear, Facebow or Tandem that are used in Class III
patients with maxillary deficiency, it has no part extruding the mouth. Especially for high angle patients with a vertical tendency of
growth, it does not cause any complications like increasing vertical dimension and openbite.
The aim of the lingual arch, that is a component of the appliance, especially advised by the inventor to be used for class III patients,
is to prevent the growth of the mandible. The figure of Enlow “V shaped transversal growth of the mandible” (Fig. 3) that is present in
Dr. Ülgen’s book (2) is a good proof that the lingual arch can be used to stop the growth of class III patients.
PARTS OF THE PROTRUSOR:
Appliance consists of two main components and ClassIII elastics:
FIRST MAIN COMPONENT (Fig. 4-8-9), is cemented to maxilla. Has similarities with the Distal Jet Appliance (American
Orthodontics Company®-Sheboygan-USA) designed by Dr.Aldo Carano and Mauro Testa in 1996 in Italy. It is stated in several studies
that force applied by Distal Jet for molar distalisation achieves 60% molar distalisation and 40% premaxilla protrusion on the upper
arch. With modifications to the Distal Jet, the force distribution is changed to make 100% premaxilla protrusion. The modifications are
as follows:
FIRST MODIFICATION: the Nance piece is larger and while covering more than half of the crown sizes of 4 upper incisor teeth it also
goes behind until the deepest depression on the palate.
SECOND MOFIFICATION: Presence of hooks enabling placement of Class II elastics on the molar bands on upper first molars.
THIRD MODIFICATION: Two molar bands are united (4) by the Transpalatal arch (TPA)(3).
FOURTH MODIFICATION: Metallic arms starting from the Nance piece and going through the vestibular part of teeth 12-11-21-11 have
hooks. They fix the Nance piece to incisor teeth by composite resin at the vestibular surface. With all these modifications the first
main component is called as “Modified Distal Jet”.
SECOND MAIN COMPONENT: (Fig.5) It is cemented to the mandible. It resembles to the appliance known as Lingual Arch. The
difference is addition of 1mm SS wire that goes through the outer surfaces of the teeth (10).It has hooks (6) enabling attachment of
ClassIII elastics at the direction of the mandibular canines (9). The second component is named as “Modified Lingual Arch”.
Class III elastic (7) this is the most important component , responsible for the system to work(Fig. 5). It is attached from the hook
of theMaxillary First Molar (4), to the hook that’s at the level of the Mandibular Canine(9). The appliance can be further modified
using a fixed piece similar to a closing coil spring instead of the Class III elastics. Also anchorage can be increased by mini-implants that
can be placed to the mesial of the first Maxillary Molar. The system fixed in patients mouth and on model is demonstrated on Fig. 8-9-
11.
The force system formed bu this appliance is schematized on Fig. 6. The forces applied to the system are represented by F on the
upper arch and the force applied between both arches by the Class III elastic (7) is represented by G. when the forces on the system
reach an equilibrium (F1 and G1 neutralize each other) the F2 force that’s in forward direction applies force leading premaxilla
forward.
CASES AND METHOD:
Of the 269 patients presented in the clinic of the author 29 were diagnosed as Class III due to retrognathic Maxilla. (according to
Witts): 10.78% 13 of the 29 patients were treated using protruzor.: 44.82% .All of the patients (2 male-11 female)that were in growth
period had premaxillary protrusion in 6 months period: 100% .Beginning and control Lateral Cefalometric X-rays of a patient using the
protrusor can be seen in Fig. 7and the comparison can be seen in Fig. 10. Analyze results can be observed in the table. The big
difference between initial and 6 month values of the angle between FH-SN-NaBa planes is noteworthy. Therefore it can be more
reasonable to take into consideration the difference between ANB,Wits (B-Ar)-(A-Ar) while analyzing the results.
HORIZONTAL SKELETAL Initial values After protrusor Normal values
SNA (º) 81.9 79,6 82,0 ± 3.5
SNB (º) 81.7 78.6 80.0 ± 3.0
ANB (º) 0.2 1.0 2.0 ± 2.4
Maxillary Skeletal (A-Na Perp) (mm) -2.3 -3,9 0.0 ± 3.1
Mand. Skeletal (Pg-Na Perp) (mm) -2.9 -6.4 -4.0 ± 5,3
Wits Appraisal (mm) -4.9 -3,4 -1.0 ± 1.0
Ar - A (mm) 77.1 75.8 93.1±4.5
Ar - B (mm) 88.8 86.4 93.1± 4.5
(B-Ar) - (A-Ar)(mm) 11.7 10.5 8.0±3.0
REFERENCES:
1- Melsen B. 1975,Palatal growth studied on human autopsy material. Am J Orthod Dentofac Orthop’ pages: 68:42-54
2-Ortodonti,Anomaliler,Sefalometri,Etiyoloji,Büyüme ve Gelişim,Tanı.
Prof.Dr.Mustafa Ülgen pages:256,282
FIGURES:
Figure 1 Figure 2 Figure 3
Figure 4 Figure 5 Figure 6
Figure 7
Figure 8 Figure 9
Figure 10 Figure 11