technological innovations related to dentures

42 Spectrum dialogue – Vol. 13 No. 7 – September 2014

Technological InnovationsRelated to Dentures

This article describes the steps related for the fabricationof removable dentures made with a new type of resinCuring system. (V.L.C.). The protocol is part of thesystematic integrated TRE, which has as its objectivethe replacement of methyl methacrylate withan auto- thermo-polymerizing (P.M.M.A.)that may be used in all procedures of thelaboratories: removable prosthesis,fixed, orthodontics, with thethese resins V.L.C.

Massimiliano Petrullo

Spectrum dialogue – Vol. 13 No. 7 – September 2014 43

Fig. 2Fig. 1

Fig. 3 Fig. 4

Fig. 5

Introduction

The procedures for the construction of a denture ororthodontic appliance may be affected by thecharacteristics of the materials used.

Among the materials used there are the dentalresins; the most often used in this field are thosebased in P.M.M.A. They tend to notoriously have a

Fig. 1: Removable denture on implants

Fig. 2: Fixed prosthesis on implants

Fig. 3: Bite

Fig. 4: Preliminary Impression

Fig. 5: Preliminary Model

number of significant operational issues in thedifferent processes and poor biocompatibility forpatients and operator as well. Historically therehave been many attempts to replace resins basedP.M.M.A. for these reasons but always with poorresult. Today, on the basis of results obtained from a2006 research I was involved in we realized as agroup of Italian dental technicians that we can saythat the new technology V.L.C. has allowedDenturists and dental technitions to enter into anew era. The system allows the Denturist to makedevices completely biocompatible to patients in areassuch as removable and fixed prosthesis andorthodontics (Figs. 1-3). The application of thesystem V.L.C. described in this article relates to theprocedures used by the Denturist which allows forresults clearly superior to those achieved withmethods which provide for the use of other types ofresins.


Fig. 6 Fig. 7 Fig. 8

Fig. 9 Fig. 10

Fig. 11 Fig. 12

Materials and methods

The operational phases described in this article havebeen appropriately divided, showing step by step thework phase in the laboratory. Pouring preliminarymodels 7, 8: The primary models are obtained fromthe alginate impressions and used for theconstruction of individual custom trays, indispensablefor a correct recording for the final impression.

Custoum trays and Impressions:

The custom trays are modeled into their form andpolymerized using special equipment, reducing theworking time and the subsequent stages of workrelating to the polymerization of the resins. Thesetrays were designed to be used for the secondaryimpressions with a technique that involves the use ofa silicon-based material. The trays were trimmedapproximately 2mm short of the peripheral border toallow for a border molded functional impression(Figs. 7-8)

Fig. 14 Fig. 15

Fig. 13

Fig. 6: Mandibular customtray

Fig. 7: Maxillary custom tray

Fig. 8: Final Impressions

Fig. 9: Boxed finalimpression

Fig. 10: Maxillary mastercast

Fig. 11: Maxillary base plate

Fig. 12: Maxillary occlusal rim

Fig. 13: Mandibular Occlusal rim

Fig. 14: Bite registration

Fig. 15: Bite registration


Fig. 18 Fig. 19

Fig. 20

Fig. 21 Fig. 22 Fig. 23

Pouring secondary models

Before pouring the secondary models, theimpression are boxed with wax to reproduce thedetails of the impressions for the future dentures(Fig. 9).

Constructing base plates

The master models at this stage, are used for theconstruction of the base plate, which plays afundamental role in the proper performance of thesuccessive phases of work. The base plates are madewith a technique innovative and easy to apply which

Fig. 16: Face bow mounting on articulator

Fig. 17: Mandibular base mounted on articulator

Fig. 18: Maxillary-mandibular anterior tooth set up

Fig. 19: Maxillary posterior tooth set up

Fig. 20: Posterior teeth set up

Fig. 21: Maxillary denture for try in

Fig. 22: Mandibular denture for try in

Fig. 23: Final carving

Fig. 16 Fig. 17

Fig. 30 Fig. 31

Fig. 32

Fig. 24: Incisal pin making contact with plate

Fig. 25: Silicone matrix

Fig. 26: Artificial teeth placed in matrix

Fig. 27: Resin applied to teeth

Fig. 28: Base on model

Fig. 29: Case back on articulator

Fig. 30: Final check

Fig. 31: Polymerised resin base for mounting and modeling

Fig. 32: Multi-silicone in the articulator with resin for fixingand modeling


Fig. 24 Fig. 25 Fig. 26

Fig. 27 Fig. 28 Fig. 29

allows the Denturist to achieve extreme accuracy. Thetransparency of the resin used also facilitates thepositioning of the denture teeth (Figs. 10-13).

Articulation

Once the denture bases are checked in the mouthand maxillary-mandibular relations obtained, the

base plates are used in laboratory, for positioning(FIG. 16 FIG. 17) on a semi-adjustable articulator.This step is performed in two stages. The mountingbegins with the upper using a facebow then the'lower with the base plates. These contain all theinformation necessary for the positioning of theartificial teeth (Figs. 14-17). The selection of theartificial teeth is deteremined on the basis of


Fig. 33

Fig. 34

Fig. 35

Fig 33: Positioning of the teeth in the articulator

Fig 34: Key Removal of silicone with the solidified resin

Fig 35: Positioning of the shaft at the starting point

measurements performed using the patient'sfacial features. The anterior teeth used on thiscase have a high aesthetic value thanks to asuperficial texture and natural morphology. Theposterior teeth have an occlusal morphology thatallows for easy use thanks to the identification ofocclusal keys that allow for lingualized occlusionwith excellent functional effects and aesthetics.

Anterior and posterior teeth are manufactured withan newly advanced technology and manufacturedusing INPEN, evolution PMMA that havecompatable characteristics.

Setting artificial teeth

Anterior positioning of the teeth takes placeaccording to the individual occlusal plane andmarkings. It starts with the maxillary anterior teethaccording to the references on the bite blockrecorded previously by the Denturist. Mandibularanterior teeth are positioned following the occlusalrims. With the aim of acquiring more information,the mandibular posterior teeth are not set for the tryin appointment.We see here two occlusal rims with the posterior

occlusal lower;

- The mounting of the maxillary posterior teeth;

The mandibular reference lines, which could beused to control the vertical dimension occlusion(VDO) (Figs. 18,19)

Positioning artificial teeth for final aproval

After the try in to assess the aesthetics, phonetics andvertical dimension, we complete the positioning ofthe mandibular posterior teeth taking intoconsideration any necessary changes. During thefinal try in the Denturist should verify all theaesthetic and functional aspects of future prosthesis.(Figs. 20-22.).

Finalization of the dentures

After the approved try in we are going to finalize thedentures. Here I will discuss the detailed steps ofpolymerization on the maxillary and mandibulardenture bases using the same technique. We prefer toperform the transformation of the prosthesis resin intwo stages for greater control and the possibility ofcontrolling possible changes during thepolymerization step. During the first stage we have toremember the initial position of the articulator pin.We use as a landmark. After securing with the wax tothe base on the models we make an occlusal matrixon the articulator making sure the pin of thearticulator keeps touching the plate. After the matrixis made we take out the teeth and we clean the waxand the same with the models. Once dry we aregoing to apply a separator. Retention holes are drilledinto all teeth before positioning and fixing them into


Fig 36: Modeling of the finished prosthesis



Fig. 39. Cured prosthesis

Fig. 40. Cured Prosthesis

Fig. 36

Fig. 38

Fig. 39 Fig. 40

Fig. 37

the matrix with proper resin. Once completed weproceed to the final step. The base is placed back onthe articulator opposing it on the matrix with teethin position using a polyethylene sheet to prevent thetwo resins from sticking together. Also in this step wemust carefully check that the pin of the articulator isin contact with the plate before the finalpolymerization (Figs. 23-29).After completing thepolymerization, the base is check on the articulator toensure the adaptation of the base to the surface ofthe teeth and the correct positioning of the pin onthe articulator plate. Once verified we apply a resin tothe base and in particular to the surfaces of theteeth. The base is set back on the articulator. Withthe base and the matrix on the articulator, it is timeto warm up the resin. Once the resins have beensoftened we close the articulator until it contacts withthe base. Further resin is added when the articulatoris closed. The resin solidifies on cooling and then

can proceed with the removal of matrix from thearticulator. In the end we verify that the pin of thearticulator is still in the initial position. Thisconfirms that everything is accurate as when theprostheses were in wax. In this phase you can stilleasily remedied errors because the resin remains ina malleable stage (Figs. 30-35). After modeling, theprosthesis is inserted in the first a heating oven, tocondition the two materials used, and then joinedand placed in a light curing unit completingpolymerization.

After this stage, the prosthesis are returned back tothe articulator and checked for occlusal discrepencies.These resins are very precise so errors are generallyvery minimal. Next we proceed to the finishing andpolishing. This step is shorter and simpler comparedwith older materials used before. Due to the absenceof the plaster mold during curing, the details of the


Fig. 41 Fig. 42

Fig. 43

dentures are much sharper and cleaner. Thefollowing pictures illustrate the results of this caseproduced using the new V.L.C. Revolution SystemTHREE (Figs. 45-46).

Discussion

The advantages of resins V.L.C. are related to theircharacteristics and physico-chemical, better th an thePMMA (data provided by the manufacturer). Thisprotocol highlights these characteristics:

1) The processing times are reduced thanks to a very precise and to a perfect control in all work stages, avoiding, for example, grinding of the teeth after the polymerization.

2) The materials are completely workable all the time that we need; the process of polymerization starts only when they are inserted into the light curing equipment.

3) The process is very ergonomic, since the

transformation is direct and does not require use plasters, flasks or other.

4) Production costs do not change; the cost is slightly higher than PMMA based materials but excess material is recovered and stored for future use, without any waste.

5) With products made with V.L.C. you can easily intervene with readjustments, during any stage until that work has been completed.

6) The use of the products V.L.C. safeguards operators from serious side effects related to the use PMMA.

7) The use of these products allows V.L.C to provide patients with devices completely biocompatible.

Conclusions

The opinions presented are the results of years ofwork and studies along with the collaboration oftechnitions, manufacturers and industry leaderswithout which this article would not have beenpossible. Considering the many departments thatuse PMMA base materials in dental laboratories, it issafe to say that this technology and associated

Fig. 44

Fig. 41: Cured Prosthesis

Fig. 42: Ready to trim

Fig. 43: Ready to polish

Fig. 44. Finished prosthesis

Fig. 45 Fig. 46

Fig. 45. Old dentures

Fig. 46. New dentures.

About the author

Massimiliano Petrullo received his diploma in dental Technology in 1985. Since 1992 he owns a dentallaboratory specializing in removable prosthesis, as well as being in charge of various managementpositions for Antlo . He is an expert in the dental production processes and provides consulting andtraining to dental laboratories looking to become accredited and aimed at achieving high quality work.He is a member of Antlo Formazione, and a member S.I.T.E.T. ( Societe International TraitementEdention Total). He has lectured nationally and international and teaches courses on removable dentures,

dental resins and their uses and applications.

He is the author of numerous scientific publications. Since 2006 he has been doing research on a newgeneration of dental resins that have a main characteristic of extreme biocompatibility. He has worked withseveral leading companies in the dental industry, as a technical-scientific consultant and currently works with thegroup Dentsply Prosthetics divisions in Italy and International.

protocols may one day solve issues related to the use the P.M.M.A. Greatbenefits will be seen for dental laboratories, dental practices and patients.

Products:Product lines V.L.C. referred to are: Triad®, Radica®, Eclipse® and In : Joy® The lines of teeth manufactured with technology Inpen and are Genios , Executive.These materials are produced and distributed by Dentsply.

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Incisal Edge Dental Laboratory – Thomas Kitsos, RDT, Owner and Principal3410 Yonge Street, Toronto, ON., M4N 2M9

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