A COMBINATION PROSTHESIS USING THIMBLE COPINGS FOR RECONSTRUCTION OF MUTILATED DENTITION : A CASE REPORT AT NOBEL MEDICAL COLLEGE

* Corresponding Author Dr Robin Singh Warainch Lecturer, Department of Prosthodontics Nobel Medical College and Teaching Hospital, Nepal Email: emailorobinsingh@gmail.com ABSTRACT Planning and execu ng the restora ve rehabilita on of a severely mu lated den on is one of the most challenging tasks for the restora ve den st. This case report illustrates an interdisciplinary approach in the treatment of a mul faceted case of par al loss of teeth. A series of provisional prosthesis were used before the final treatment due to extreme complexity of the pa ent situa on. The final treatment was composed of innova vely designed thimble copings, telescopic retainer and cast metal frame work for the rehabilita on of the maxillary and mandibular arch.


INTRODUCTION
The par al loss of den on can lead to various problems in the mas catory system of the pa ent which can be func onal, 1,2 biological and aesthe cal.This can lead to minor or major movements of the le out teeth in the arch and loss of ver cal dimension of occlusion (VDO) can occur by supra 2, 3 erup on of the opposing teeth.This clinical report demonstrates an interdisciplinary approach in treatment planning of a complex case of par al edentulism.Due to extreme complexity of the pa ent's intra oral situa on, the final treatment was accomplished a er series of provisional prosthesis.The final treatment involved innova vely designed thimble copings and telescopic crowns as retainers for fixed removable prosthesis that uses the concept of telescopic a achments and takes support from the fixed retainers as well as remaining teeth as abutments thus making it hybrid prosthesis.

CASE REPORT
A 52 year old par ally edentulous male pa ent reported to the Department of Prosthodon cs for the management of complex intra oral dental situa on.In his chief complaint pa ent said that he was unhappy with his dental condi on as it affected his quality of life.The pa ent wanted be er esthe cs, feasible and affordable treatment plan which would enable him to eat be er and provide sa sfactory esthe cs.
Intra orally, the prominent features were as follows: the pa ent had undergone mandibular fixed prosthesis treatment few years back, which had dislodged and the pa ent was not more using it from past few months, par ally edentulous maxillary arch with missing 15, 16,17 and par ally edentulous mandibular arch with missing teeth as follows 31, 37, 46 and 47 (Figure 1).None of the teeth were mobile.The tooth 47 had silver amalgam restora ons.In the maxillary arch 12 had arrested caries, 16, 24 and 25 had composite restora ons and core built up done.Measuring the ver cal dimension of occlusion (VDO) revealed increase in freeway space (6mm).Radiographic assessment indicated minimal bone loss around the abutment teeth and increase alveolar bone loss bilaterally in the maxillary arch.No periapical pathology was revealed and there was no sign of temperomandibular disorder.
The pa ent was stabilized by oral hygiene measures and oral hygiene instruc ons were emphasized before considering any rehabilita ve treatment.
A er obtaining the study casts, anterior deprogramming device was used to deprogram the oral musculature and intra oral bite registra on using bite registra on material (Imprint, 3M ESPE, USA) was taken in centric rela on posi on.The face-bow was used to ar culate the diagnos c casts to a semi adjustable ar culator (Whip Mix Corpora on, USA), using bite registra on which was previously obtained.Subsequently, it was possible to assess the poten al treatment op ons closely and any adjunc ve procedure required.
The Unilateral group func on occlusion scheme was planned on the principles of biological occlusion described by Becker and Kaiser but due to loss of tooth structure of both mandibular canines, the occlusion scheme was changed to bilateral group func on.The treatment op ons presented were: • Maxillary arch restora on with fixed par al denture.
• Mandibular arch rehabilita on with combina on prosthesis using thimble coping and crowns on all the natural teeth remaining and followed by a fixed removable prosthesis which used a cast par al denture 4 like framework in the edentulous area.

Defini ve treatment planning:
All possible treatment op ons and outcomes were discussed with the pa ent.Despite the pa ents preference for a fixed par al denture for mandibular arch, hybrid fixed removable prosthesis using telescopic retainers was chosen to facilitate greater home care and oral hygiene measures as pa ent had compromised periodontal status in mandibular arch due to poor oral hygiene.

Prosthe c rehabilita on of Maxillary arch:
Tooth prepara ons of 14, 16, 17, 24, 25 and 27 were modified, followed by gingival retrac on and impression was made using polyvinyl siloxane impression material (Reprosil, Dentsply India).(Figure 2) Heat cure provisional restora ons (DPI heat cure tooth molding powder, Dental products of India, Mumbai) were fabricated according to the diagnos c wax up and were Case Report Warainch RS et al cemented with temporary cement (Rely X Temp NE, 3M ESPE products).The face bow was used to ar culate the maxillary cast on a semi adjustable ar culator.

Rehabilita on of Mandibular arch:
In the mandibular arch tooth prepara ons were refined and modified wherever possible to receive cast metal copings.
Excessive modifica ons to the tooth prepara ons could not be done due to loss of tooth structure in previous fixed par al denture prosthesis (Figure 3).Following gingival retrac on, impression of mandibular arch was made using polyvinyl siloxane impression material (Reprosil, Dentsply India).Heat cured provisional restora ons (DPI heat cure tooth molding powder, DPI, India) was fabricated and tried on semi adjustable ar culator and adjusted to Bilateral Group Func on scheme.It was checked intra orally in the pa ent's mouth and necessary correc ons were done.
Madibular cast was obtained and ar culated to the semi adjustable ar culator using intra oral bite registra on which was obtained using bite registra on material in centric occlusion.
During the modifica ons of tooth prepara ons it was taken care that tooth prepara ons were modified to achieve near parallel axial walls wherever possible.This is because parallel the walls of the coping, the greater mechanical fric on interlocking of the coping with the overlying crown.The parallel axial walls of short teeth offer be er resistance 5 form.Grooves were prepared in buccal and lingual walls of the abutments to achieve more reten on.Wax pa ern were fabricated with cervical shoulder, surveyed to check their parallelism and were cast in chrome cobalt alloy.Cast coping were also surveyed to check the parallelism and determine most suitable path of inser on of the defini ve prosthesis.A er required adjustments, coping were cemented using GIC (FUGI, GC Corpora on, Tokyo, Japan).(Figure 4) Final impressions were made to record the anatomical details of the metal copings.The mandibular master cast was obtained from this impression and was then duplicated in reversible hydrocolloid duplica ng material (WiroGel M, Bego, Germany) to obtain the refractory cast for the fabrica on of cast metal framework.Intra oral bite record was used to ar culate the maxillary cast against mandibular refractory cast.The defini ve waxing for mandibular cast metal framework was performed along with wax up for copings for over crowns (PFM) on 32, 33, 34, 38, 41, 42, 43, 44, 45, 46.A metal try in was performed to verify intra oral fit, reten on and stability.
Ceramic facing crowns were fabricated with buccal half ceramic and lingual half metal and to receive half over crown on 35, 38, 46 and removable par al denture framework on 36, 37 and 47 with cobalt chrome framework.
The cobalt chrome framework was highly polished a er final glazing of porcelain fused to metal crowns and occlusion was adjusted on the ar culator and conferred to bilateral group func on.(Figure 5a, b) The maxillary fixed prosthesis was cemented using GIC (FUGI I, GC corpora on, Tokyo, Japan).
(Figure 6a, 6b) Case Report Warainch RS et al The mandibular defini ve prosthesis was checked intra orally in pa ent's mouth and intra oral fit, reten on stability and occlusion was verified.(Figure 7a, b) Instruc ons were given to the pa ent regarding using prosthesis and for regular cleaning of the prosthesis at night and oral hygiene instruc ons were emphasized.The pa ent is being followed up regularly and is sa sfied with the performance of the prosthesis.There is no complaint of any pain or discomfort in TMJ region.
a b

DISCUSSION
The reconstruc on of a severely mu lated den on is very complex and difficult problem for the restora ve den st.A wide range of restora ve treatment op ons are possible with today's materials and techniques.A fixed removable prosthesis using telescopic crown retainers was taken as treatment op on for this pa ent.This design involves an inter surface fric on during the inser on and removal of the super structure as two parts engage and disengage 6, 7 themselves.Also , this design maintains the integrity of the arch by keeping all the healthy teeth in the arch as abutments for the copings.This gives the pa ent a prosthesis that has far more support than any conven onal prosthesis.Instead of so , movable mucous membrane, the prosthesis literally sits on teeth "piling", enabling the prosthesis to withstand a much greater occlusal load without 8 movement.The telescopic overdenture consists of a primary coping or inner telescope, permanently cemented to the abutment tooth and a congruent secondary or outer crown, rigidly anchored in the removable prosthesis.The secondary crown engages the primary coping to form a telescope retainer unit.The coping protects the abutment tooth from caries and thermal irrita ons and provides the basic element for reten on and stabiliza on of outer part.The secondary crown, being an integral part of the removable prosthesis serves as its anchor with the rest of the den on.
The implant supported prosthesis was other treatment op on discussed with the pa ent.As the implant based prosthesis offers a lot of advantages in the shape of improved reten on, more stability and support, low bone loss, be er esthe cs but the higher cost of the 13 prosthesis had restrained the pa ent from op ng for it.And also this type of design of prosthesis facilitates easy removal and inser on of prosthesis which makes home care and cleaning of the prosthesis rela vely easy for the pa ent.So, integra on of fixed and removable prosthodon cs was planned for this pa ent.A mul disciplinary approach was taken to rehabilitate the pa ent's mu lated dental status in an organized way.The successful integra on of fixed and removable prosthodon cs has resulted in accurately fi ng, esthe cally pleasing and func onally efficient prosthesis.Periodic follow up and me culous prosthesis maintenance by the pa ent will hold the key for the ul mate success of these types of rehabilita on procedures.

CONCLUSION
The successful rehabilita on of the present pa ent's intra oral situa on stresses the importance of judicious use of prosthodon c principles and accurate treatment planning in addi on to team work between the special es of the den stry.The op mal and esthe cally pleasant occlusion was achieved in the present case although there was severe disfigurement of the occlusal plane.This complex looking fixed-removable prosthesis not only restored the pa ent's esthe cs desires but also offered added advantage of being removable so that pa ent can perform be er oral hygiene measures and thus prolonging the life of span of prosthesis and the abutments.

Case Report
Warainch RS et al