Rpd Dual Path

Rotational Path Removable Partial Denture (RPD):Conservative Esthetic Treatment Option forthe Edentulous Mandibular Anterior Region:A Case Report

JENNIFER S. SUH, DMD*

EDWARD J. BILLY, DMD

ABSTRACTIt can be esthetically and financially daunting for patients to lose teeth in an anterior region ofthe mouth. For these patients, traditional treatment options presented in the past have includedfixed partial denture, implants, and conventional removable partial denture (RPD). For patientsfaced with financial, anatomical, and/or esthetic limitations, the edentulous region can berestored successfully with a rotational path RPD. Rotational path RPD designs have often beenoverlooked by the dental profession due to its complex concepts involving the prosthetic designand sensitive laboratory techniques. With better understanding of the concepts and design, thedental clinician can deliver the highest esthetic outcome in compromised areas in which othertreatment options may often face limitations. This paper reviews the method used to estheti-cally design and plan a posterior-anterior rotational path RPD in an edentulous mandibularanterior region for a patient missing the mandibular incisors.

CLINICAL SIGNIFICANCEDue to inadequate understanding of the mechanics of rotational path RPDs, many clinicianshave not adapted the application of this advantageous prosthesis. When correctly designed andfabricated, the rotational path RPD provides improved esthetics, cleanliness, and retention forpatients who may not be suitable candidates for implants or fixed partial dentures in tooth-supported edentulous regions.

(J Esthet Restor Dent 20:98107, 2008)

I N T R O D U C T I O N

Despite the advanced tech-niques available to replaceedentulous areas with implanttherapy, there remains a groupof patients who are not goodcandidates for implant therapy.

This group of patients may lackfinancial resources and may havepoor systemic health, fear of dentalsurgeries, and psychological oranatomical limitations.1 Patientswho fit into the aforementionedcategories have the option ofreceiving a removable partial

denture (RPD) prosthesis to replacemissing teeth. In place of the some-times cumbersome and unestheticconventional RPD design forreplacing teeth in the missing man-dibular anterior region, the rota-tional path RPD has become apopular treatment option. The

*Graduate prosthodontics resident, Department of Biologic and Material Science, The University of Michigan,School of Dentistry, Graduate Prosthodontics, Room 1378, 1011 N. University, Ann Arbor, MI 48109-1078

Clinical professor, Department of Biologic and Material Science, The University of Michigan,School of Dentistry, Graduate Prosthodontics, Room 1378, 1011 N. University, Ann Arbor, MI 48109-1078

2 0 0 8 , C O P Y R I G H T T H E A U T H O R SJ O U R N A L C O M P I L AT I O N 2 0 0 8 , B L A C K W E L L P U B L I S H I N GDOI 10.1111/j.1708-8240.2008.00158.x V O L U M E 2 0 , N U M B E R 2 , 2 0 0 898

rotational path prosthesis offersthe advantage of improved esthet-ics by eliminating anterior clasps,shortened treatment duration,cleanliness, and lower treatmentcost over implants or fixed partialdentures.13 The need for anesthetic RPD involving anteriorpontics gave rise to the dual pathRPD concept first introduced byKing and Garver in 1978.3 Byeliminating anterior clasping, thistechnique utilizes proximal under-cuts adjacent to the edentulousspaces for retention.2,46 In thebeginning, the dual path designwas limited to tooth-borne situa-tions where anterior teeth weremissing; however, clinicians areapplying the concept to other eden-tulous spaces.4 This article reviewsthe method used to estheticallydesign and plan a posterior-anterior (PA) rotational path RPDin an edentulous mandibular ante-rior region for a patient missingmandibular incisors.

B A S I C R O TAT I O N A L PAT H

R P D C O N C E P T

The rotational path design conceptuses a rigid retainer portion of theframework as the retention compo-nent.2,5,6 The anterior-posterior, PA,and lateral rotational path designsare popularly used in KennedyClass IV situations.1 The proximalplate provides retention through itsintimate contact with the proximaltooth surface below the height ofcontour at a zero-degree tilt.2 These

rigid retentive components gainaccess along the first path, to eng-age into the undercuts, and then aremaneuvered into rotation to fullyseat the prosthesisthe second andcompleted path of insertion.2,3 Onlya minor connector, a guiding plane,or a small rigid extension of theframework into a desired undercutis required for retention.5 The effec-tiveness of the rotational pathdesign is dependent on the one ortwo conventional clasp assembliesplaced on the prosthesis.2

PA R A M E T E R S O F R O TAT I O N A L

PAT H R P D

According to Krol and colleagues,6

there are more advantages thandisadvantages in utilizing rota-tional path RPD. Clinicians shouldevaluate patients on an individualbasis and determine if a rotationalpath design is possible.

The rotational path RPD designoffers many advantages.6 Itrequires minimal number of clasps,and hence, reduces tooth coverageand decreases plaque accumula-tion. By eliminating anterior clasps,the esthetics can be better manipu-lated, compared with fixed partialdentures, around the gingivaldefects, with closer acrylic adapta-tion. The abutment teeth prepara-tion is conservative compared withfixed prosthesis or a precisionattachment, and the design doesnot require lingual or facial under-cuts. Also, rotational path RPD

prevents further tipping of abut-ment teeth contacted by the rigidretainer. Despite many of theseadvantages, the rotational pathRPD design also has several dis-advantages.6 Communication witha competent laboratory technicianis crucial, as the rigid retentivecomponent is difficult to adjustand the RPD is less tolerant to anyfabrication and processing errors.Lastly, the design requires well-prepared rest seats.

C L I N I C A L A P P L I C AT I O N :

C A S E S T U D Y

HistoryA 72-year-old White male pre-sented to the graduate prosth-odontics clinic of the University ofMichigan dental school seeking anevaluation for ways to improvefunction and esthetics. The patientwas given a fixed (FPD #2226and implant FPD #2326) versusRPD treatment option anddecided to accept the removabletreatment option. The patientsgoal was to receive a comfortableand functional prosthesis with nosurgical treatment. His medicalhistory revealed no significantmedical findings and his generalhealth was excellent. During theclinical examination, the followingproblems were noted: teeth #5and #23 to #26 were missing,and teeth #18 and #31 presentedwith existing gold crowns. Thepatient was not interested inreplacing tooth #5 at the present

S U H A N D B I L LY

V O L U M E 2 0 , N U M B E R 2 , 2 0 0 8 99

time. Rest seat preparations in theexisting gold crowns were to beprepared with no perforation aftercareful evaluation of occlusal rela-tionship in the mounted casts. Thepatient exhibited canine guidanceocclusal relationship bilaterallyand exhibited no parafunctionalhabits. His acceptance to theremovable prosthesis treatmentplan was very philosophicalaccording to the Houses classifi-cation, and the treatment wasprojected to have a good long-term prognosis.

C L I N I C A L P R O C E D U R E

Diagnosis and Treatment PlanA facebow (Water Pik Tech Inc.,Newport Beach, CA, USA) wasused to help relate the diagnosticcasts, which were mounted onto asemiadjustable articulator (HanauWide Vue-Articulator II andfacebow, Water Pik, Inc., FortCollins, CO, USA). It was

important to have mounted caststo evaluate the available interarchspace and to determine the appro-priate surfaces to place occlusalrest seats (Figure 1).

Survey CastsThe mandibular cast was placedon a surveyor table (DentsplyCeramco, Ney Surveyor, Yucaipa,

CA, USA) and was surveyed at azero-degree tilt. The analyzingrod was used to determine theamount of undercut present onthe mesial surface of the caninesand mesial-lingual undercut onmolars. Three separate verticallines were placed on the cast toorient it at a zero-degree tilt(Figures 2 and 3). The cast was

Figure 1. Importance of mounted casts for interocclusalspace evaluation.

Figure 2. Tripodized casts at zero degrees.

Figure 3. The direction of the first path of insertionindicated.

R O TAT I O N A L PAT H R P D A S T R E AT M E N T F O R A N E D E N T U L O U S M A N D I B U L A R A N T E R I O R R E G I O N

100 2 0 0 8 , C O P Y R I G H T T H E A U T H O R SJ O U R N A L C O M P I L AT I O N 2 0 0 8 , B L A C K W E L L P U B L I S H I N G

tilted straight back from theinitial survey lines until the under-cuts on the mesial surfaces of thecanines were eliminated. Once thetilt on the surveyor was deter-mined, three additional verticallines were drawn next to theinitial vertical lines (Figure 3). TheRPDs will have better retentionthe more divergent the surveylines are from each other. Thepreliminary height of contouroutline was drawn on the diag-nostic cast, and the followingmodification areas were indicatedon the cast: rest seats, retentiveareas, undercuts, and guidingplanes for completion with thepatient (Figures 4 and 5).

RPD Framework DesignMajor framework rest seats andtooth modifications were com-pleted on the patient by buildingup Gradia composite (GC-America,Alsip, IL, USA) cingulum restseats7 on the lingual surfaces ofcanines, and disto-occlusal rest

seats (1.5-mm-deep)2 were pre-pared with an inverted-conediamond bur on teeth #18and #31 (Figure 5, Table 1).Although full-coverage surveycrowns may be more beneficialto prevent composite wearagainst the mechanical frictionof the prosthesis over time,many authors810 haveadvocated bonded restorationsto improve contours andto alleviate the patientsfinancial constraints.

Custom Tray Fabrication andDefinitive PVS ImpressionThe flange portion of a Triadcustom tray (Dentsply Trubyte,York, PA, USA) was border-molded using green stick com-pound (Kerr Dental, Orange, CA,USA). The definitive cast impres-sion was taken using a light-bodyExtrude polyvinylsiloxane (KerrDental) to capture the details ofthe rest seats and a heavy bodyto fill the rest of the tray(Figure 6).

Figure 4. The distance between the two heights of contouron the canine should be as far apart as possible for betterretention.

Figure 5. Composite cingulum restseats were placed on canines.

TA B L E 1 . R E M O VA B L E PA R T I A L D E N T U R E ( R P D ) F R A M E W O R K D E S I G N .

Teeth Rest Undercut Clasps

22 Cingulum No electroplating on mesial guideplane; block out lingual rest

NA

27 Cingulum No electroplating on mesial guideplane; block out lingual rest

NA

18 DO ML Akers (1/2 round)31 DO ML Akers (1/2 round)

Major connector: lingual bar.

RPD metal framework: Wironium (Zedan Lab, Farmington Hills, MI, USA).

Retentive area: lattice design.


V O L U M E 2 0 , N U M B E R 2 , 2 0 0 8 101

Prepared Master Cast Sent tothe LaboratoryAfter the master cast was poured,trimmed, and resurveyed, a labora-tory authorization was written tocommunicate with the laboratoryfor the fabrication of the frame-work. It was important to specifynot to provide relief around themesial guide planes of the abutmentteeth #22 and #27, as this was

critical for allowing rigid retainersto engage in undercuts (Figure 7). Itis important to instruct the labora-tory not to electropolish the guideplane areas in order to prevent theloss of retention. For rotationalpath RPDs, each retainer consistsof a rest and a guide plane as theretentive element, which avoids theuse of clasps, especially in theesthetic zone.

Framework Try-InThe framework was tried in themouth to check for retention bypulling on the meshwork areato see if it unseats and toevaluate the proper sittingof the RPD around the restseats, guide plane, and clasps andthe fit of major connectors(Figure 7).

Set Selected Teeth according toShade and ShapeCorrect shade and shape of theteeth were selected by evaluatingthe patients remaining dentitionas a guide. Gingival shadewas also taken at thesame appointment.

Mount Mandibular Cast againstthe Maxillary CastMandibular cast was mounted tothe opposing cast in order towax-up the edentulous area.Figure 6. PVS impression with a custom tray.

A B

Figure 7. Intimate adaptation of framework around the abutment teeth.



Esthetic Try-InTeeth have been set and waxed-up for the esthetic try-in appoint-ment. The RPD was gently placedin the mouth, and the followingcriteria were evaluated: heightof the teeth, occlusal interferences,esthetics, and phonetics (Figure 8).

Wax-Up, Process RPDAfter obtaining the patientsapproval for the wax-up and tooth

setup, the RPD was processedusing light-fibered pink Lucitone(Dentsply Trubyte).

Placement of Definitive RPDThe processed RPD was placed inthe mouth, and the following crite-ria were reevaluated: adaptation ofthe clasps and rests, retention ofthe RPD, esthetics, and occlusion(Figures 9 and 10).

Patient EducationThe patient was instructed inplacing the prosthesis by seatingthe posterior part of the RPDfirst and then seating the anteriorsection until it clicked into theedentulous area by utilizing thePA rotational path. Oral hygieneinstruction was provided, whichstressed the importance of recallmaintenance appointmentsto evaluate the prosthesis as

A B

Figure 8. Wax try-in.

A B

Figure 9. Delivery of final prosthesis. Notice the adaptation of acrylic resin to the adjacent tooth.


V O L U M E 2 0 , N U M B E R 2 , 2 0 0 8 103

well as the health of theremaining dentition.

C O N C L U S I O N

With partially edentulous patients,clinicians are challenged toimprove on treatment plans andutilize alternative RPD designs toprovide comfort and to meet thecurrent esthetic dental standards.The rotational path of insertionconcept satisfies this current needof patients opting to receive aremovable treatment plan.1 Byrotating an RPD into position,fewer clasps are utilized. A carefulexamination of the patients exist-ing dentition can allow a rotationalpath RPD to be designed properly.Rotational path RPD can providean alternative treatment option toimplants for medically compro-mised patients who cannot gothrough the surgical phases ofimplant therapy. Rotational pathRPD is clinically significant in that

it can deliver satisfactory estheticsand function for patients that iscomparable with fixed partialdenture or implant therapy.1,6 Byutilizing the existing undercutspresent in the dentition, rotationalpath RPDs can be inserted usinga dual path placement. One of themain advantages of rotational pathRPDs is the claspless design in theesthetic region. Because of theclose adaptation requirements ofretentive components, an intimatetooth contact by the rests allowsvery little room for error while theRPD is fabricated.6 It is importantfor the clinician to build a closerelationship and communicate wellwith the laboratory technician forthe successful fabrication of arotational path RPD.6 It seems thatmany dentists have a fear or lackof trust in their ability to delivera predictable RPD prosthesis, andthus avoid recommending thistreatment to their patients.5 The

long-term success of an RPD canbe very predictable with the properattention to oral hygiene,periodontal considerations,basic design concepts, andjudicious fabrication of partialdenture construction.4

D I S C L O S U R E A N D

A C K N O W L E D G M E N T S

The authors do not have anyfinancial interest in the companieswhose materials are included inthis article.

The authors gratefullyacknowledge the support andencouragement given byDr. Michael Razzoog.

R E F E R E N C E S

1. Ancowitz S. Esthetic removablepartial dentures. Gen Dent2004;42(5):4523.

2. Jacobson TE, Krol AJ. Rotationalpath removable partial denture

A B

Figure 10. C-clasp adaptation around teeth #18 and #31.



design. J Prosthet Dent1982;48(4):3706.

3. King G. Dual-path design for removablepartial dentures. J Prosthet Dent1978;39(4):3925.

4. Becker CM, Kaiser DA, Goldfogel MH.Evolution of removable partial denturedesign. J Prosthodont 1994;3(3):15866.

5. Christensen GJ. What has happened toremovable partial prosthodontics? JADA2003;134:1113.

6. Krol AJ, Jacobson TE, Finzen FC.Removable partial denture design. 5th ed.

San Rafael (CA): Indent; 1999, pp.7893.

7. Toth RW, Fiebiger GE, Mackert JR Jr.,Goldman BM. Shear strength oflingual rest seats prepared in bondedcomposite. J Prosthet Dent1986;56(1):99104.

8. Latta GH. A technique for preparationof lingual rest seats in light-curedcomposite. J Prosthet Dent1988;60(1);127.

9. Wong R, Nicolls JI, Smith DE. Evalua-tion of prefabricated lingual rest seats forremovable partial dentures. J ProsthetDent 1982;48(5):5216.

10. Yard RA, Butler GV, Render PJ. Bondedcomposite rests: a fabrication method.J Prosthet Dent 1988;60(1):1289.

Reprint requests: Jennifer S. Suh, DMD,Department of Biologic and MaterialScience, The University of Michigan Schoolof Dentistry, Graduate Prosthodontics,Room 1378, 1011 N. University, AnnArbor, MI 48109-1078. Tel.: 734-763-3326;Fax: 734-764-1481; e-mail: [email protected]


V O L U M E 2 0 , N U M B E R 2 , 2 0 0 8 105

Rpd Dual Path

Documents

Transcript of Rpd Dual Path