5. Sectional Rpd

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African Journal of Biomedical Research 2007 (Vol. 10) / Dosunmu, Arigbede and Ogunrinde

Sectional Removable Partial Denture Design for Partial Mandibulectomy treatment 198

INTRODUCTION

Tumors in the mandible usually require surgicalremoval with or without resection of normal bone atthe margins of the lesion. Smaller lesions removedwithout discontinuity of the bone are relativelysimple to restore with prosthesis while larger lesionsmay be more difficult to restore even though thecontinuity of the mandible is maintained (Shu-thicMou et al,2001).

The prognosis for edentulous segmentalmandibulectomy patient becomes less favourable asthe size of the resection increases (Shu-thic Mou etal,2001; Beumer et al, 1996). Success of prosthesisfor resected edentulous mandibule is directly relatedto the amount of the remaining bone, the numberand integrity of remaining teeth and continuity ordiscontinuity of the bone defect (Martin et al , 1994 ).Frequently surgical reconstruction of the defect isrequired to re establish the continuity of themandible through bone graft or to create a buccal orlingual sulcus to provide a suitable tissue foundationfor an acceptable prosthesis Cantor and Curtis(1971). In addition, pre- prosthetic implantplacement may be required to improve dentureretention and stability. Failure of reconstructivesurgery for mandibulectomy patients often makesprosthetic rehabilitation extremely difficult.

The presence or absence of natural teeth in aresected mandible often determines the approach toprosthetic rehabilitation. Cantor and Curtis (1971)classified edentulous mandibular resection patientsby the amount of mandible that remains afterresection and surgical reconstruction. Although theclassification was suggested for edentulous patients,it is also applicable to partially edentulous patients(Firtell and Curtis, 2002).

The classification aids the understanding of thetreatment need of the patient and the challenges of prosthetic rehabilitation of mandibulectomy patient.

Classification of Mandibular Resection Patient(Cantor and Curitis, 1971)

In class I mandibular resection patient, there isradical alveolar resection and the continuity of themandible is preserved (fig 1A). The class I patientfunctions well with removable partial denture,though may have some anatomic or functional

limitations.In class II mandibular resection patient, the total

mandible has been resected distal to the canine (fig1B). In this class there is associated loss of functionof the attached muscle resulting in deviation of theremaining mandible toward the surgical defect.When compare to class I patient, they are moredifficult to rehabilitate with prosthesis

The class III mandibular resection patient hasthe mandible resected to the midline or possiblybeyond (fig 1c). The patient in this class presentswith increased problems with mandibular deviationand denture instability.

The Class IV mandibular resection patient hashad a lateral resection and subsequent boneaugmentation to form a pseudoarticulation of boneand soft tissue in the region of the ascending ramus(Fig 1 c). In this class of patients there is lessmandibular deviation.In class V mandibular resection patient, there isanterior resection that crosses the midline butbilateral mandibular articulation has beenmaintained and the continuity of the mandible hasbeen restored surgically by placing an autogenousbone graft.

The class VI mandibular resection patient issimilar to class V patient but the continuity of themandible has not been restored surgically.Because each lateral fragment moves individually,the prognosis for a removable prosthesis is poor.

Design of prosthesis for mandibular resection of partial edentulous patient should follow the principleof partial denture design 5. However the applicationof these principles in mandibular resection patientmay vary due to the specific need of each patient.Rehabilitation of class VI mandibular resectionpatient is a great challenge in prosthodontics. Theindependent movement of each lateral fragmentgives unstable support for prosthetic fabrication andloss of anterior base of tongue leads to loss of tongue control and difficulty in controlling theprosthesis.

Sectional DentureA sectional or two-part denture is a type of removable partial denture designed to overcomeproblems of opposing proximal undercut in relationto unilateral partial denture (Lamine and Laird,


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1986; Walter, 1980)It is designed to engage and utilize opposing

proximal undercuts on mesial and distal abutmentteeth, which will result in positive retention in bothvertical and lateral direction often withoutincorporating a conventional clasp. Each part of thedenture will therefore have its individual path of insertion and once in position the part will bemaintained in position by means of a locking bolt toform a whole unit. The technical construction of such an appliance is naturally more complex than aconventional denture.

This article describes the fabrication of anacrylic sectional denture for a class VI mandibularresection patient who had undergone anteriorsegmental mandibulectomy with no surgicalreconstruction.

CASE REPORTA 37 year old female patient presented forremovable partial denture replacement of missing

54321 12345,nine months post surgical resection of anteriorsegment of the mandible.

On examination there is discontinuity defect of the anterior part of mandible with independentmovement of the lateral segments (fig. 2). The rightsegment is relatively more stable than the left.The teeth remaining in the mandible were the

876 678and the resected segment involved the sockets of 5 5 (fig 2). The remaining teeth in the mandiblewere stable clinically and radiographs showed thatthe bone support is good. In the maxillary jaw, allthe teeth were present and healthy.

Surgical reconstruction of the defect andprosthetic rehabilitation were suggested as treatmentof choice. However, the patient refused any furthersurgical intervention because of financial problems.

Therefore, it was decided that all acrylicsectional denture would be fabricated for the patient.

Clinical and Technical Consideration inProsthesis FabricationA plastic stock lower impression tray was cut intotwo halves and impression of the lower arch wasmade with irreversible hydrocolloid in two separatesections; each segment of the arch in one-halve of

the impression tray.The two halves impressions were poured

separately in hard dental stone. The right and leftlower arch casts obtained were occluded with upperarch cast and a locating overcast was made to thebase of the right and left lower arch cast to alignthem.

A record block was fabricated in wax and thebite registered. The registration of intercupsalposition was achieved by manual guidance of themandible into the required position. Wax trialdenture was set up without the right lingual flangeand try-in was carried out. The right lingual flangeswere later waxed up with the set up trial denture.The whole wax denture was invested and processedin permanent heat cure denture resin.

Figure 1Diagram showing classification of resected edentulousmandibulae. Edentulous mandibular resection patients areclassified by remaining structures (a) Class I. Alveolar resection(b) Class II, total resection distal to cuspid. (c) Class III, totalresection to midline or beyond (d) Class IV, total resection withpartial reconstruction (e) Class V, total anterior resectionreconstructed surgically. (From Cantor, R., and Curtis, T. A(1971).


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suitable tissue foundation for acceptable prosthesis.The mucosa-borne acrylic sectional denture was

made as temporary measure later to be replaced withdefinitive tooth-borne metal base denture whenpatient is financially ready.

The class VI mandibular resection patients aredifficult to rehabilitate with prosthesis because of theindependent movement of the lateral mandibularsegments. Previous author 4,5 have advocated noprosthetic rehabilitation for edentulous patient in thisclass however, literature on rehabilitation of resectedpartially edentulous class VI patients is rare.

In this case, the two lateral jaw segments moveindependently and could only align when closed andtheir standing teeth occlude with upper arch teeth.Hence nothing can be introduced into the mouth asany attempt resulted in severe pain from the TMJsand soft tissues.

A single lower arch impression was not possiblethereby requiring taking the impression of each jawsegment separately. Also, the try-in of the wax trialdenture was not feasible which necessitated try-inwithout the right lingual flanges. Fabrication of denture in the laboratory was less difficult becausethe models of the right and left mandibular segmentshave been aligned with a locating matrix.

The finished denture was able to be inserted insections and the two jaw segments allowed to moveinto occlusion before locking with the adapted S. S.wire. The locked sectional acrylic partial denturestabilized the two jaw segments to open and close

(fig. 5).The denture provided gave support to the

collapsed lip, restored function, improved theaesthetics and was well tolerated by the patient.

REFERENCES

Beumer J. III rd , Curtis TA, Marunick MT (1996): Maxilofacial rehabilitation: Prosthodontic and surgicalconsiderations. 1 st ed. St. louis (MO): Ishiyaku EuroAmerica, Inc: 202-206Cantor R., Curitis T.A. (1971): Prothetic management of edentulous mandibulectomy patients. Part 1: Anatomy,physiologic and psychologic consideration. J. ProsthDent; 25: 446.Firtell D.N, Curtis T.A (2002): Removable partialdenture design for the mandibular resection patient.University of California. School of Dentistry, SanFrancisco Calif.Lamine G.A., Laird W.R.E. (1986): Osborne andLammies partial dentures; 5 th edition, Black well scientificpublications.Martin J.W., Lemon J.C, King G.E (1994): Maxillofocial restoration after tumour ablation, Clinplastic surg 1994; 21: 87 96Shu-thic Mou, Tsongi Chai, Yuh Yuan Shiau, Juo-Song Wang (2001): Fabrication of conventional completedentures for a left segmental mandibular patient a clinicalreport. J Prosth Dent. 86: 542-545Walter J. O. (1980): Partial denture technique 7 Sectional Denture. Brit dent. J.148: 257 260.

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