|Year : 2015 | Volume
| Issue : 3 | Page : 154-157
Functionally generated pathways to develop occlusal scheme for removable partial denture
Pravinkumar G Patil1, Smita P Nimbalkar-Patil2, Rahul S Kulkarni3
1 Division of Clinical Dentistry, School of Dentistry, International Medical University, Kuala Lumpur, Malaysia
2 Department of Orthodontics, Faculty of Dentistry, MAHSA University, Kuala Lumpur, Malaysia
3 Department of Prosthodontics, Nair Hospital Dental College, Mumbai, Maharashtra, India
|Date of Web Publication||28-Apr-2016|
Pravinkumar G Patil
Division of Clinical Dentistry, School of Dentistry, International Medical University, Kuala Lumpur
Source of Support: None, Conflict of Interest: None
| Abstract|| |
The functionally generated pathway (FGP) technique consists of registering the occlusal pathways of the posterior teeth in the functional wax and has been classically described as the "three-dimensional static expression of dynamic tooth movement." This clinical report describes the treatment of a partially edentulous patient, with a cast removable partial denture, in which occlusion was developed using the FGP procedure. The FGP technique utilizes the patient's masticatory system to develop occlusion and has the advantages of being simple, accurate, and reliable. If the FGP technique is properly accomplished, only minor intraoral occlusal adjustments are necessary. This article described a technique of developing the FGP occlusion for a patient with cast partial denture with Kennedy's Class III edentulous mandibular arch.
CLINICAL RELEVANCE TO INTERDISCIPLINARY DENTISTRY
The FGP is highly versatile technique of developing the occlusion-pattern in the removable and fixed dental prostheses including implant restorations. It can be employed with equal efficacy in fabrication of relatively simple restorations such as a single crown, or more complex full mouth reconstructions.
Keywords: Fixed prosthodontics, functionally generated path, occlusion, removable prosthodontics
|How to cite this article:|
Patil PG, Nimbalkar-Patil SP, Kulkarni RS. Functionally generated pathways to develop occlusal scheme for removable partial denture. J Interdiscip Dentistry 2015;5:154-7
|How to cite this URL:|
Patil PG, Nimbalkar-Patil SP, Kulkarni RS. Functionally generated pathways to develop occlusal scheme for removable partial denture. J Interdiscip Dentistry [serial online] 2015 [cited 2019 Jun 19];5:154-7. Available from: http://www.jidonline.com/text.asp?2015/5/3/154/181380
| Introduction|| |
The functionally generated pathways (FGP) of occlusion refer to the registration of the paths of movement of the occlusal surfaces of the teeth of one dental arch, to the teeth or occlusion rims of the opposing arch, recorded with the help of a plastic medium. The technique of obtaining such records consists of registering the three-dimensional (3D) occlusal pathways of cusps of posterior teeth in the functional wax, with acceptable condylar and anterior guidance and normal occlusal anatomy. The FGP is formed by scribing or engraving the wax recording medium or occlusion rim by the opposing cusps with lateral, protrusive, and excursive border movements of the mandible. After registration of the FGP record, a stone-occlusal-template is formed, and artificial teeth are arranged against it. The occlusion achieved with the help of this technique is considered to be in great harmony with controlling factors of occlusion namely, the anterior and condylar guidance, occlusal cusps, and the neuromuscular system. Classically, the FGP occlusion has been described as “3D static expression of dynamic tooth movement,” since exact occlusal pathways of posterior teeth are captured three-dimensionally in the functional wax. The technique was introduced by Meyer ,, almost 70 years ago, which he termed as the “chew-in” technique, and since then various researchers have refined the procedure. Over the years, the technique has been known by various names such as “functional chew-in technique,” “functional bite technique,” “generated path technique,” and “cuspal tracing technique.” The FGP is highly versatile and has been employed with equal efficacy in fabrication of relatively simple restorations such as a single crown, or more complex full mouth reconstructions. It has also been used in developing occlusion for complete and partial dentures and dental implant restorations.
| Clinical Report|| |
A 42-year-old female reported to the Department of Prosthodontics, seeking replacement of missing teeth and recementation of a dislodged fixed dental prosthesis (FDP). The patient presented with a partially edentulous mandibular arch, with missing mandibular right second premolar and first and second molars, and a dislodged three unit metal ceramic FDP replacing the mandibular left first molar. Patient's past dental history revealed extraction of previously mentioned teeth due to dental caries 2 years ago, followed by fabrication of FDP to replace the left first molar. The patient complains of recurrent dislodgment of the FDP. Patient's right side of mandibular arch was not restored after extractions. Spacing was observed due to small sized maxillary lateral incisors; however; the patient was not concerned about this. The centric occlusion position was coincident with the maximum intercuspal position. It was observed that there was no supraeruption of maxillary molars of right side besides the long-term history of missing opposing mandibular molars, and the plane of occlusion was acceptable. Initial diagnostic procedures included making of diagnostic impressions and casts, radiographs, face bow transfer and diagnostic mounting, fabrication of special tray, and evaluation of patient's expectations. As a part of the treatment planning, patient was presented with the options of dental implants for edentulous areas and conventional fixed and removable partial dentures (RPDs). Patient declined the option of dental implants citing financial reasons and accepted the latter alternative. Hence, the definitive treatment plan consisted of metal ceramic FDP for the mandibular left first molar, and the cast RPD for replacement of mandibular right premolar and molars, for which informed consent was obtained from the patient.
Initial therapy consisted of oral prophylaxis, oral hygiene instructions, diet counseling, and the provisional FDP for missing left molar. As a part of definitive treatment plan, replacement of mandibular left first molar with metal ceramic FDP was undertaken. Previously treated abutments were modified to improve retention and resistance form, as there was a history of recurrent dislodgment with the previous FDP. Gingival retraction, polyvinyl siloxane impression, and bite registration were carried out following the standard treatment principles. A definitive cast was created with Type IV dental stone (Ultrarock; Kalabhai Karson, Mumbai, India). After full contour waxing was completed, mandibular first premolar and molar were cut back, and surveying of the cast was carried out in a conventional manner. The occlusal rest was carved in waxed-up crown on second molar, and favorable undercut was created on its buccal surface for placement of embrasure clasp. Areas that could be used for retention, and guiding planes were located on the cast, and favorable contours of abutments were obtained by changing the tilt of the cast initially, followed by altering contours of the abutments on the cast.
Design and fabrication of removable partial denture
The design of prospective mandibular RPD consisted of a lingual bar major connector, onlay rest on a right third molar, occlusal rests and clasps on abutments, appropriately placed parallel guide planes, and a ladder loop design of minor connector for the denture base. Mouth preparations were carried out following the surveying and designing. Fabrication and cementation of metal ceramic FDP were carried out following standard technique [Figure 1]. A day after the cementation, impression of mandibular arch was made in a border molded special tray, with a medium body polyvinyl siloxane impression material (Aquasil Medium Body; Dentsply Austenal, York, PA, USA). A functional impression was deemed unnecessary due to the presence of the distal abutment and firm mucosa overlying the residual ridge. Impression was poured using Type IV gypsum to obtain the master cast. The master cast was indexed with the tripod markings and surveyed, and the undercut areas were blocked out with the blockout wax (Ney Undercut Wax; Dentsply Ceramco, Burlington, NJ, USA). The blocked out cast was duplicated to form a refractory cast, and the wax pattern was prepared. The framework was casted in a cobalt-chromium alloy (Vitallium 2000; Dentsply Austenal, York, PA, USA) following standard laboratory procedures. Framework was finished and polished, returned to the master cast, and temporary denture base was added to the framework. Framework was tried intraorally, the fit was verified, and it was confirmed that there was no interference by any component or the record base in centric occlusion and excursion.
Recording of the functionally generated pathway
The FGP records were planned to record the maxillomandibular relationship with the cast metal framework in place. Before recording the FGP, it was confirmed that the metal framework along with the denture base was firm, stable, and retentive intraorally. It was also examined that there were no interferences in the anterior guidance and the posterior teeth had acceptable occlusal anatomy. Occlusion rim was created on the base plate using hard inlay wax (Inlay Wax Blue Hard; Kerr Corporation, Orange, CA, USA), and visible gap was left between opposing teeth and the rim initially [Figure 2]a. Softened inlay wax was added to the rim, and the framework was placed intraorally. Patient was asked to close in centric occlusion to indent the soft wax. It was ensured that all natural teeth were in contact, and the framework was removed when the wax got hardened. Wax was softened again, and the previous exercise was repeated. Now, the patient was instructed to protrude his/her mandible in forward direction without losing teeth-contact until the incisors were at edge-to-edge relationship. Similarly, the lateral excursive pathways were also recorded for both right and the left side [Figure 2]b. The patient was instructed to glide the mandible through all possible excursive movements to ensure capturing all border movements. The wax was repeatedly softened between each biting episode. Once all excursive pathways were recorded, the record was hardened by keeping under the cold water. It was observed that the inlay wax was smoothly carved and shaped by the stylus action of the opposing maxillary cusps.
|Figure 2: (a) Try-in of partial denture framework with inlay wax attached for occlusal registration. (b) Obtaining functionally generated pathway record in eccentric relation|
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Mounting of the casts
The FGP record obtained was used to fabricate the stone occluding template. To accomplish this, the record was reseated and secured onto the master cast [Figure 3]a, and boxing was done with the modeling clay and the modeling wax as shown in [Figure 3]b. Only wax registration and areas for vertical stops were left exposed, and it was filled with the dental stone to form occluding template [Figure 4]a. Recording the FGP eliminates the need to reproduce mandibular movements on the articulator, and hence the mounting was done on a simple three-point (mean value) articulator. The cross-linked acrylic resin teeth (Acry rock; Ruthinium Dental Products, Badia Polesine, Italy) matching the shade of patient's natural dentition were selected. Teeth were arranged high up initially, and then progressively modified to exactly fit the occluding template at the established vertical dimension [Figure 4]b. Waxing and carving were done after teeth arrangement and try-in was carried out in a conventional manner. The trial denture was processed using standard laboratory procedures, during which autopolymerizing resin of denture base was replaced with the heat-polymerized resin (Lucitone 199 Denture Base Resin; Dentsply Trubyte, York, PA, USA). The cast partial denture was issued, and the postinsertion instructions were given to the patient regarding maintenance and use of the prosthesis [Figure 5]. During the denture delivery, the occlusal refinement was carried out, and the group function occlusal scheme was confirmed. At the 6 and 12 months recall visits, no treatment complications were noted.
|Figure 3: (a) Functionally generated pathway record seated on master cast. (b) Modeling clay used to block specified areas on the cast|
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|Figure 4: (a) Occluding template with functionally generated pathway record mounted. (b) Occlusal surfaces of teeth modified to fit occluding template|
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|Figure 5: Postoperative view with removable partial denture in occlusion|
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| Discussion|| |
The FGP technique is highly versatile and has been employed with equal efficacy in fabrication of crown, bridge, complex full mouth reconstructions, complete, and RPDs as well as dental implant restorations. It is recognized that the Pankey–Mann philosophy of occlusal rehabilitation was originally a combination of the Monson spherical theory and the Meyer functionally generated path technique, where they attempted to gain bilateral balance in eccentric movements.,, The Pankey–Mann–Schuyler philosophy retains the FGP technique, except that the balancing side contacts are eliminated due to their traumatogenic effect on the masticatory system. If the FGP technique is properly accomplished, only minor intraoral occlusal adjustments are necessary. Besides, the availability of the sophisticated fully adjustable articulators, the FGP still remains a technique that is simple, reliable, and unsurpassed in accuracy., As outlined by Brecker, “The human jaw, with all its limitations, with all its interferences, and with all its problems created by habit, makes the best articulator. Consideration should be given to the patient's individual pattern of chewing.” Functionally generated path technique utilizes the patient's masticatory system to develop occlusion and has the advantages of being simple, accurate, and reliable.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]