Case report

Removable partial denture with molar uprighting spring:

An innovative hybrid appliance

Jitendra Rao MDSa,*, Gulshan Kumar Singh MDSb, Habib Ahmed Alvi MDSa,Lakshya Kumar MDSa, Kaushal Kishor Agrawal MDSa

a Department of Prosthodontics, Faculty of Dental Sciences, King George Medical University, Lucknow, Indiab Department of Orthodontics, Faculty of Dental Sciences, King George Medical University, Lucknow, India

Received 13 July 2011; received in revised form 27 June 2012; accepted 6 August 2012

Available online 11 November 2012

Abstract

Patient: A 45-year-old female patient with need of fixed replacement of her missing teeth which were lost long time before. Posterior teeth were

severally tipped bilaterally in the edentulous space. Hybrid removable partial denture with molar uprighting spring was fabricated for molar

uprighting on both side tilted molars. After 3 month and 15 days of treatment with hybrid appliance the molar abutment were uprighted for

fabrication of fixed partial dentures.

Discussion: The objective in molar uprighting is ideal positioning of the molar which will eventually become an abutment tooth for a fixed

prosthesis. The ideal position will provide an optimal periodontal environment for the molar. The prosthodontic advantages of molar uprighting via

distal tipping include an improved line-of-draw if a FPD is being constructed. Concept of designing of appliances was based on our basic

knowledge of forces for uprighting the tooth along with maintaining the function during the treatment period. Another advantage of this appliance

was that it prevented supra eruption of opposing teeth during the period when the molar was being uprighted.

Conclusion: Uprighting of tilted molar is extremely beneficial for long term success of fixed denture prosthesis by using hybrid appliances in very

short period of treatment without hampering the function of the patient during the treatment period which is very economical as well.

# 2012 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.

Keywords: Abutment; Edentulous; Occlusion; Rehabilitation

www.elsevier.com/locate/jpor

Available online at www.sciencedirect.com

Journal of Prosthodontic Research 57 (2013) 57–61

1. Introduction

Masticatory system is the functional unit of the body [1]

which works under complex neuromuscular control for its

function like chewing, swallowing and speaking. Proper

function causes the proper trituration of food as a result of

which the digestive process starts in the oral cavity itself.

During its function, teeth and alveolar bone are constantly

being subjected to deleterious forces. Nature has provided such

equilibrium that by complex anatomy of roots and periodontal

ligament these forces are being well tolerated by the tooth itself

and the alveolar bone.

In the process of aging, some teeth are lost due to caries,

periodontal disease or other reasons which create an imbalance

* Corresponding author at: 103, Grandeur apartment, C-979, Sec-B, Maha-

nagar, Lucknow, U.P, India-226006. Tel.: +91 09415576398;

fax: +91 08858540048.

E-mail address: drjit123@rediffmail.com (J. Rao).

1883-1958/$ – see front matter # 2012 Japan Prosthodontic Society. Published b

http://dx.doi.org/10.1016/j.jpor.2012.08.004

in the equilibrium and the integrity of masticatory system is

lost. When these missing teeth are not replaced properly for a

long time they have a tendency to migrate towards the empty

space in an attempt to fill the space. The tooth distal to the

extraction site will drift mesially into the space [1]. Nearly 98%

of posterior teeth tilt mesially when subjected to occlusal forces

[2]. This result in dispersal of stresses around the apices of teeth

in the alveolar bone in a manner which is quite different from

the stress patterns produced in the alveolar bone by loading of

normal teeth. As a result of tilting and drifting of teeth, stresses

are being concentrated in some areas which lead to resorbtion

of bone in that area causing weakened periodontal support of

teeth while planning the fixed prosthodontic therapy. The

drifting and changes in mesiodistal angulations of teeth in

extraction space is a common problem which affects the

occlusion. In such patients with severe changes in mesiodistal

angulations, it is very difficult to fabricate prosthesis

(removable or fixed partial dentures) even after using surveyors.

If prosthesis is fabricated in such conditions, it may not be able

y Elsevier Ireland. All rights reserved.

Fig. 2. Uprighting spring made up of 0.45 mm (18 mil) stainless steel wire.

Fig. 3. (a) and (b) Steps of fabrication of appliance.

Fig. 1. Model showing wire bending for appliance (bands are placed with

buccal tubes welded along long axis of molar).

J. Rao et al. / Journal of Prosthodontic Research 57 (2013) 57–6158

to achieve proper chewing force or it may affect the abutment

teeth adversely.

If the tilting is severe more extensive corrective measures are

called for. The treatment of choice is uprighting of molar by

orthodontic treatment [3]. Uprighting is best accomplished by

the use of a fixed appliance [4].

The over-all objective in molar uprighting is ideal

positioning of the molar which will eventually become an

abutment tooth for a fixed prosthesis. The ideal position will

provide an optimal periodontal environment for the molar [5].

This case report describes the concept to design an appliance

using our basic knowledge of forces for uprighting the severely

tilted bilateral molar abutment. Fabrication of this design is

easy, convenient as well as very cheap and can be planned at

any age without hampering masticatory function during the

course of treatment.

2. Case report

A 45-years old female reported to the department of

prosthodontics with need of fixed replacement of her missing

teeth which were lost longtime before. Intra oral examination

revealed that patient had missing mandibular teeth on right side

46, 47 and left side 35, 36. Mandibular molars 37, 38, 48 were

severally tipped in the edentulous space on both sides. After

discussion, molar uprighting was planned for both side tilted

molars which were to be used as abutments for fixed partial

denture. Patient was not willing for expensive fixed orthodontic

treatment so a hybrid removable partial denture with molar

uprighting spring was fabricated. After 3 months and 15 days of

treatment with hybrid appliance the molar abutment were

uprighted for fabrication of fixed partial dentures on both side

of the mandibular arch.

3. Clinical innovation

Patient came to our department for replacement of

bilaterally missing teeth 35, 36, 46, 47 in the mandibular arch

due to difficulty in chewing and mastication. Dental history

revealed that patient had missing teeth from around 8 years for

which she did not receive any prosthetic treatment. Intraoral

examination indicated distal abutment drifted mesially into the

edentulous space. Orthopantomogram (OPG) was taken to

measure the degree of tilt. When calculated the degree of tilt

was 388 on the right side and 428 on the left side making it a

contraindication as fixed partial dentures are not indicated for

more than a tilt of 258 [3]. Tylman stated that mandibular

molars that are tipped beyond 248 should not generally be used

for fixed partial denture abutments [5].

Molar uprighting takes around to 1–11/2 years for the tilted

teeth to straighten and serve as an abutment for fixed partial

denture. The treatment cost with fixed orthodontic treatment was

too much that the patient was unable to afford. This prompted us

to design an innovative cost effective device that can helpful in

molar uprighting as well as patient’s need of chewing and

mastication. So we decided to design a hybrid removable partial

denture with springs to upright the molars simultaneously on

both side as well as to solve the masticatory problem of the

Fig. 5. (a) Key for engaging and disengage the spring. (b) Uprighting spring

after activation.

Fig. 4. Complete appliance assembly ready for delivery.

Fig. 6. (a) and (b) Patient’s intraoral photographs before and at the time of delivery of appliance.

Fig. 7. Patient intraoral photographs (a) Before delivery of appliance. (b) At the time of delivery of appliance. (c) After 3 months and 15 days of treatment.

J. Rao et al. / Journal of Prosthodontic Research 57 (2013) 57–61 59

patient. Many literatures are available to manage tilted abutment

but rare or no literature is available to upright the tilted abutment

by use of removable partial denture with spring.

4. Appliance design and fabrication of hybridprosthesis

I. The molar which has to be uprighted were banded after

separation on right side and Begg’s buccal tube was spot

welded on bands along long axis of molar. Impression

was made in irreversible hydrocolloid (Zelgan, Dentsply).

Impression was poured with bands positioned in the

impression (Fig. 1).

II. Cast was poured with dental stone (Kalabhai type III) so

that in the model dental stone tilted tooth were banded as

in the patient mouth.

III. After the casts were obtained they were articulated in the

proper intercuspal position. Teeth were set in wax

maintaining as near to normal interocclusal contacts as

possible.

Fig. 9. (a) Pre treatment OPG. (b) OPG after molar uprighting.

Fig. 8. (a) Right side view in occlusion. (b) Left side view in occlusion. (c)

Mandibular arch after correction.

J. Rao et al. / Journal of Prosthodontic Research 57 (2013) 57–6160

IV. Uprighting spring is made up of 0.45 mm (18 mil)

stainless steel wire after teeth were set in wax. The

uprighting spring has three parts (Fig. 2):

a. Retentive arm: From the mesial end of the vertical loop

wire is bent in lingual direction to embed in the acrylic

of hybrid removal orthodontic appliance.

b. Vertical loop with helix: Consist of helical vertical loop

of 8–10 mm with coil of 3.0 mm diameter and 1.5

circles to increase the length, flexibility and range of

action of the wire.

c. Lever arm: From the distal end of vertical loop wire is

bent parallel to the occlusal plane and a vertical bend is

given to engage the spring in the molar buccal tube.

V. A removable orthodontic appliance with a pontic for

extraction space and an uprighting spring was fabricated

from 0.45 mm (18 mil) stainless steel wire. Pin head

retention clasps were incorporated for retention (Fig. 3a

and b).

VI. The whole set up in wax was then flasked and cured with

clear heat cure acrylic (Trevalon, Dentsply). Finished and

polished appliance assembly which is ready for deliver.

VII. Patient was wearing the appliance comfortably since then

(Fig. 4).

VIII. The uprighting spring were then activated by opening the

loop (1 mm) and were engaged in the buccal tube with the

help of key fabricated by 21 gauge (0.72 mm) wire

(Fig. 5a). The forces generated were very light and

relatively constant.

IX. At every 4–6 weeks, reactivation of the uprighting spring

was done by disengaging the appliance and opening the

coil, adjusting and then re-engaging the tail in buccal tube

(Fig. 5b) by patient herself as guided through a key

(Fig. 5a).

X. During course of the treatment patient’s intraoral

photographs with band (Figs. 6a and 7a), at the time of

delivery of appliance (Figs. 6b and 7b) and after

completion of uprighting of molars (Fig. 7c).

XI. Optimum and expected result were achieved (approxi-

mately 208 on right side and 248 on left side) on both sides

after 3 and 1/2 months (Figs. 8a–c and 9a and b) as evident

by patient’s orthopantomogram (OPG) and thereafter

patient was successfully rehabilitated by fixed prostho-

dontic treatment (Fig. 10a–c).

5. Discussion

A multidisciplinary approach to this type of dental therapy is

ideal and that since treatment planning in individual cases

varies greatly, each malocclusion and associated periodontal

involvement should be evaluated on an individual case basis

[6]. A mesially tipped mandibular molar if allowed continuing

drifting is eventually ‘‘pounded’’ into the mandible. Great

pressure is exerted on the alveolar bone along the mesial aspect

of the root. Bone resorption, increased mobility, and finally loss

of the tooth will take place [7]. If these teeth are used as

abutment for fixed partial dentures it will lead to failure of

prosthesis. Close inter-relation of periodontal health and

Fig. 10. (a–c) Intraoral photographs after FPD placement.

J. Rao et al. / Journal of Prosthodontic Research 57 (2013) 57–61 61

correct prosthetic function is of the atmost importance. The

prosthodontic advantages of molar uprighting via distal tipping

include an improved line-of-draw if a bridge is being

constructed, or improved space and marginal ridge relations

if an implant-borne prosthesis is planned [8]. The periodontal

advantages of uprighting a mesially tipped molar include

elimination of the pseudo pocket that often forms on the mesial

aspect of these teeth [8] thus it is necessary to straighten the

abutment tooth first and then plan for fixed partial denture.

Orthodontic uprighting with fixed therapy is costly and takes a

long time at least three month [9] during which function is

hampered. Thus we designed an appliance using our basic

knowledge of forces for uprighting the tooth along with

maintaining the function during the treatment period. Another

advantage of this appliance was that it prevented supra eruption

of opposing teeth during the period when the molar was being

uprighted. Undoubtedly the cost of fabrication was quite less

than fixed orthodontic therapy and the patient was comfortable

wearing this appliance.

6. Conclusion

Practice of dentistry brings lots of challenges many times in

various forms. Tilted molar abutment is a major problem during

the treatment planning of any FPD. Uprighting of tilted molar is

extremely beneficial for long term success of fixed denture

prosthesis by using hybrid appliances in very short period of

treatment without hampering the function of the patient.

References

[1] Okeson JP. Management of temporomandibular disorders and occlusion,

6th ed., Philadelphia, USA: Mosby Elsevier; 2008. p. 59.

[2] Picton DC. Tilting movement of teeth during biting. Arch Oral Biol

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[3] Shillingburg HT, Hobo S, Whitsett LD, Jacobi R, Brackett SE. Funda-

mentals of fixed prosthodontics, 3rd ed., Chicago: Quintessence; 1997 .

pp. 98–9.

[4] Khouw FE, Norton LA. The mechanism of fixed molar uprighting appli-

ances. J Prosthet Dent 1972;27:381–9.

[5] Tylman S. Theory and practice of crown and bridge prosthesis, 2nd ed., St.

Louis: The C.V. Mosby Company; 1947. p. 20.

[6] Roberts WW, Chacker FM, Burstone CJ. A segmental approach to man-

dibular molar uprighting. Am J Orthod 1982;81:177–84.

[7] Linkow LI. Mesially tipped mandibular molars. J Prosthet Dent

1962;12:554–8.

[8] Shellhart WC, Oesterle LJ. Uprighting molars without extrusion. J Am Dent

Assoc 1999;130:381–5.

[9] Simon RL. Rationale and practical technique for uprighting mesially

inclined molars. J Prosthet Dent 1984;52:312–5.