160

Complete dentures over resorbedridges: enhancing stability and esthet-ics with posterior platforms

Guilherme E. P. Henriques1Mauro A. A. Nbilo1Marcelo F. Mesquita1

1DDS, MS, PhD Associate Professors,Department of ProsthodonticsCampinas State University - PiracicabaDentistry School -Piracicaba - SP - Brazil

Received for publication: February 17, 2003Accepted: March 07, 2003

Correspondence to:Guilherme Elias Pessanha HenriquesRua Campos Sales, 2006 / 92CEP: 13416-310Piracicaba - SP - Brazile-mail: guilherm@fop.unicamp.br

Abstract:A modified teeth arrangement protocol and a procedure to incorporateposterior balancing platforms in complete dentures have been described.The use of platforms is an approach to achieving stability in denturesover resorbed residual ridges due to bilateral contacts in eccentric rela-tions. Esthetic results are enhanced due to vertical overbite in centricand interocclusal distance in eccentric relations.

Key Words:Complete dentures; resorbed ridges; posterior platforms

Braz J Oral Sci. January/March 2003 - Vol. 2 - Number 4

161

Braz J Oral Sci. 2(4): 160-163 Complete dentures over resorbed ridges: enhancing stability and esthetics with posterior platforms

Introduction:Physiological, esthetic and functional variables areassociated with successful conventional complete denturetherapy 1. Despite the development of dentures supportedby osseointegrated implants, rehabilitation of resorbedresidual ridges is still a challenge 2.Balanced occlusion is an important factor associated withstability of complete dentures3. Bilateral contacts duringeccentric movements are well known and an acceptedtechnique 3, 4. However, clinical experience shows that estheticproblems usually occur due to the absence of verticaloverbite in centric and absence of interocclusal distance ineccentric positions. In addition, patients frequently reportdislodgment of dentures during alimentary bolus interposition.This article describes a technique to incorporate stabilityand esthetics in complete dentures using posterior balancingplatforms. A modified artificial tooth arrangement protocolfollowed to facilitate the inclusion of posterior platforms isalso presented.

Clinical and laboratory procedures:The rehabilitation of a complete edentulous patient withadvanced resorption of inferior ridge (Fig. 1) is used toillustrate the construction of the dentures with the platformsand the artificial teeth arrangement protocol.1- Make final impressions and mount maxillary cast inarticulator with face bow adjustment. In this report, asemiadjustable non-arcon type articulator (Dentatus ARL AB Dentatus Hgersten - Sweden) was used2- Mount mandibular cast in centric occlusion and adjustthe articulator condylar path. Central bearing tracing device(Fig.2) and protrusive and lateral relation records (Fig. 3) atappropriate vertical dimension of occlusion were applied toadjust condylar guidance, Bennett angle and incisal table.The indicated values were recorded and reproduced duringartificial teeth arrangement.3- Construct maxillary and mandibular acrylic bases onmaster casts.4- Select the artificial teeth. Vivosit / Orthosit (IvoclairAktiengesellschaft Schaan Liechtenstein) artificial teethwere used in this case.5- Set articulator condylar spheres, incisal table and incisalpin to centric occlusion.6- Wax maxillary central incisors on the acrylic base and tryit in to verify esthetics.7- Reassemble maxillary base in the articulator and waxmaxillary incisors and canines.8- Make a mandibular occlusion rim following maxillary centralincisors edges and mandibular retromolar pads as landmarks.9- Set both articulator path slopes according to protrusiverecord and lock condylar balls posteriorly with the protrusionscrews. Adjust the incisal table and incisal pin at protrusiveposition.

10- Arrange mandibular incisors in an edge to edgearticulation with maxillary incisors (Fig. 4).11- Simultaneously, wax mandibular posterior platforms inthe third molar regions following occlusal plane andcondylar guidance 5, 6. While in protrusive position, waxsuperior platforms in contact with the pre-waxed mandibulardevices.12- Readjust condylar path, incisal table and incisal pin inright working side position and screw left condylar balls.13- Set right mandibular canine in an edge to edge articulationwith maxillary right canine. Adjust left posterior platformson the working side canine through lateral excursion to permitbalancing contact.14-Repeat the procedure to left mandibular canine and rightbalancing platform.15-Return the articulator to its starting position (condylarguidance and Bennett angle at 00 on both sides) and arrangepre molars and molars in centric occlusion excluding bilateralmandibular and maxillary first pre molars to allow amplitudefor posterior devices.16-Check the absence of contacts between posteriorplatforms in centric occlusion (Fig. 5).17- Invest and pack the dentures as usual.18- Compensate dimensional changes during processingwith remounting procedure and check centric contacts aswell as the effectiveness of posterior platforms in eccentricocclusion relations (Fig. 6).19- Follow laboratory protocol for finishing, trimming andsmoothing procedures.20- Insert the dentures and verify esthetics, phonetics andocclusion (Fig 7). Assure that posterior platforms fulfillexpectation during protrusive and lateral movements. Ratifysimultaneous contact between incisors and right and leftposterior devices in protrusive and working side canine-non working side devices in lateral relations (Fig. 8).

Figure1 - The condition at initial appointment and the reabsorbedinferior ridge.

162

Figure 2 - Central bearing device for gothic arch tracing

Figure 3 - Articulator set-up with eccentric records.

Figure 4 - The articulator locked in protrusive and mandibularcentral incisors waxed in an edge to edge situation with maxillaryincisors.

Figure 5 - Teeth arrangement during the wax-up and thecontacts of the posterior platforms in protrusive.

Figure 6 - Complete dentures after smoothing procedures. Notethe interocclusal distance during protrusive and the contacts ofposterior platforms.

Figure 7 - The dentures after insertion and the natural verticaloverbite in centric occlusion

Braz J Oral Sci. 2(4): 160-163 Complete dentures over resorbed ridges: enhancing stability and esthetics with posterior platforms

163

Figure 8 - The effectiveness of posterior platforms andinterocclusal distance during eccentric relation.

Discussion:The occlusal pattern obtained with posterior platformssuggests a mutually protected occlusion. Actually, it worksas a balanced occlusion with the addition of the posteriorplatforms. This pattern allows excellent esthetic due to naturalvertical overbite from 1 to 3 mm.Stability during protrusive and lateral relations can beobtained even over advanced residual ridge resorption.Displacement of dentures during alimentary bolusinterposition is rare in contrast with balanced occlusionpattern since interocclusal distance is obtained andsimultaneous teeth-platform contacts occur throughoutmasticatory lateroprotrusive movements.Moreover, the grinding procedure and the flattened ofocclusal relief until equal bilateral contacts exist 3, 7 is avoidedsimplifying the technique and improving chewing efficiency.

Significance:In contrast with balanced occlusion pattern, the posteriorplatforms enhance esthetics due to physiological verticaloverbite in centric position. Interocclusal distance is alsoobtained during protrusive and lateral relations allowingspace for alimentary bolus and an improved chewingefficiency.

Acknowledgements: The authors are indebted to Dr. Krunislave Antnio Nbilo(Piracicaba - SP, Brazil), for his support for this prosthesisassemble method.

References1. Jendrensen M D, Allen EP, Bayne SC, Donovan TE, Hansson

TL, Klooster J et al. Annual review of selected dental literature:Report of the Committee on Scientific Investigation of theAmerican Academy of Restorative Dentistry. J Prosthet Dent.1997; 78: 54-92.

2. Henry P J. Future therapeutic directions for management of theedentulous predicament. J Prosthet Dent. 1998; 79: 100-6.

3. Dubojska A N, White, G E, Pasiek S. The importance of occlusalbalance in the control of complete dentures. Quintessence Int.1998; 29: 389-94.

4. Lang, B R. Complete denture occlusion. Dent Clin North Am.1996; 40: 85-101.

5. Sears V H. Fundamental factors in tooth articulation. J DentRes. 1928; 8: 339-52.

6. Merritt A. Scientific management of factors in bilateralprosthetic occlusion. J Am Dent Assoc. 1948; 37: 542-53.

7. Bauer A, Gutowski A. Gnathology Introduction to theory andpractice. 1st ed. Berlin: Quintessence; 1976. p.148-227, 431-507.

Braz J Oral Sci. 2(4): 160-163 Complete dentures over resorbed ridges: enhancing stability and esthetics with posterior platforms