SEMINAR recent advances in Removable partial denture

Removable partial denture
Recent advances

1. RECENT ADVANCES IN RPD Dr. Sivakumaran J 2 nd year postgraduate student Department Of Prosthodontics Including Crown & Bridge And Implantology College Of Dental Sciences, Davangere . Staff in-charge: Dr. Veena S Prakash Professor Department of Prosthodontics including Crown and Bridge and Implantology College Of Dental Sciences,Davangere .

2. CONTENTS Introduction Definition Parts of RPD Pros and Cons of most popular alternatives High Performance Polymers CAD CAM in RPD PEEK in RPD Implant assisted RPDs Future needs in RPD Conclusion References

3. INTRODUCTION Removable partial dentures have been used since the mid-19th century, and with the development of porcelain teeth by SS White and Vulcanite rubber by B.F. Goodyear, both removable partial dentures and complete dentures gained broader use. Since then, significant developments in materials, techniques, designs, and impression materials have occurred that have improved the quality of the removable partial dentures (RPDs) and the lives of partially edentulous patients.

4. With the growth in the geriatric population, including a high percentage of partially edentulous patients, the use of Removable Partial Dentures in clinical treatment will continue to be predictable treatment option in clinical dentistry. As rightly stated by Dr. M. DeVan , "the preservation of that which remains, is more important than the meticulous replacement of that which has been lost." This statement has formed the foundation for present removable partial prosthodontics. The gradual discovery of principles of RPD designing over the past century has lead to the formulation, diversification and appropriate placement of each component of the prosthesis.

5.               DEFINITION "A Removable Prosthesis that replaces missing teeth in a partially dentate arch, and can be removed or replaced by the patient himself"

6. TYPES OF RPD Acrylic Partial Denture Cast Partial Denture

7. PARTS OF RPD Removable Partial Dentures Connectors Minor Major Indirect Direct Denture Base Retainers Rest

8. PRINCIPLES OF RPD DESIGN Design of removable partial denture should be Simple Comfortable Harmless to the remaining teeth

9. BIOLOGICAL CONSIDERATIONS Teeth and periodontal tissue Inclination of abutment Status of residual ridge Types of edentulous ridge Occlusion MECHANICAL CONSIDERATIONS Retention Stability Support

10. SEQUENCE OF RPD DESIGN Rest Retainers Minor connectors Major Connectors RPD

11. INDICATIONS FOR RPD Length of edentulous span that contraindicates use of FPD No abutment tooth posterior to edentulous space Reduced periodontal support of remaining teeth Need for cross-arch stabilization Excessive bone loss of residual ridge

12. 6. Physical or emotional problem of the patient 7. Esthetics of primary concern in replacement of multiple missing anterior teeth 8. Need to replace teeth immediately after their extraction 9. Patient desire 10. Economical status

13. PROS AND CONS OF THE RPDs AVAILABLE IN THE MARKET METALS Esthetically undesirable Metallic taste Can slowly torque teeth Increase expense, further restorations FLEXIBLES Prone to bacteria buildup Low strength and creep resistance ACRYLIC Sore spots in the mouth Low impact strength, acrylic dentures are made thicker in sections, making them bulky

14. RECENT ADVANCES IN RPD

15. HIGH PERFORMANCE POLYMERS Ultaire AKP is the only High performance polymer currently on the market specifically indicated for RPD 60% lighter than typical metal  RPDs Does not leach in water, ethanol and hexane Designed to enhance the rigidity of the polymer to be supportive Very long lifetime Have some flexibility and elasticity It is Bio compatible, non mutagenic, non catatoxic , non irritant and non pyrogenic

16. Most of these materials have yet to undergo the complete physical evaluation needed to advocate their clinical use as a permanent prosthesis Some of the problems encountered with these materials include color stability, difficulty for repair, high risk for fracture, and surface changes, but most importantly they lack rigidity and support. In addition, the lack of rests and other basic RPD components of fundamental design philosophy can lead to complications.

17. Studies are needed to examine the impact of the increased flexibility of these prostheses on the hard and soft tissues as well as patient satisfaction. New approaches to design concepts such as the possible elimination of reciprocal/bracing arms with the use of deal flexible clasps also need to be considered.

18. RPDs USING THERMOPLASTIC RESIN “Non metal clasp denture” (NMCD) was referred as the generic name of RPDs with retentive elements (resin clasps) made of thermoplastic resin The NMCDs are classified into two types Flexible structure that lacks a metal framework (Flexible dentures) Rigid structure that includes a metal framework

19. INDICATIONS (FLEXIBLE DENTURES) Patients with metal allergy With few missing anterior teeth Patients in need of less occlusal support Esthetics is the top priority Patients who do not consent to preparation of abutment teeth

20. ADVANTAGES Esthetics Better comfort due to soft surface Metal allergy Discoloration and degradation of thermoplastic resin Difficulty in polishing as the surface gets easily damaged Reduced mechanical properties leading to easy breakage of clasps Lead to poor oral Hygiene DISADVANTAGES

21. Correct maintenance protocol for these non-metal clasp dentures (NMCDs) : With increased use of digital technology, these NMCDs are more readily available because they can be directly milled or printed without the high cost associated with metal frameworks. Although the clinical use of NMCDs is increasing, they have never been advocated to replace metal frameworks as a definite treatment RPD because of their properties and lack of scientific evidence. This may in part be due to their variance from accepted RPD design components such as rests.

22. Data  acquisition  is  either  performed  directly  in  the patient's mouth  (intra oral)  or  indirectly  after  making  an  impression  and  fabricating  a  master  cast  ( extraoral ). DIGITAL IMPRESSIONS

23. There are four major systems in the market today iTero by  CADent LAVA COS by 3M ESPE CEREC by Sirona E4D by D4D Technologies. iTero CEREC Lava COS E4D image

24. CEREC E4D iTero LAVA COS Full-arch digital impressions indicated YES NO YES YES Powdering Required YES NO NO Some Acquisition Technology Blue light LED Red Light LASER Confocal Blue light LED video In-Office Milling YES YES NO NO Connectivity to Labs YES NO YES YES Restoration Design (CAD) Software YES YES NO NO Indication for bridges YES NO YES YES

25. Less patient discomfort Time-efficient Simplified clinical procedures No more plaster casts Better communication with the dental technician Better communication with patients ADVANTAGES

26. CAD CAM SYSTEMS IN RPD These are evolving  to  improve  the  accuracy and  fit  while reducing  costs,  time, and  labor Digital  files  can  be  saved  and  easily  reproduced  without  additional  clinical  appointments  for  an  impression  if  another prosthesis  is  necessary. Many  dental  laboratory  technicians are  using  laboratory  scanners  to  image  the  master  dental cast  and  then  using  design  software  to  digitally  design the RPD  frameworks This  process replaces  the  conventional technique.  lnstead   of  fabricating  an  investment  cast  with wax  patterns,  a  wax  pattern  of  the  framework  is  printed

27. printed  wax  pattern  of  the  framework  is  used    to  traditionally cast  a  metal  framework similar,  if  not  better,   accuracy  and  fit    compared  with  those fa bricated by  traditional  methods. better  3D  visualization  for  designing  framework  for  students. ​

28. RPD metal frameworks may be directly  fabricated from other digital fabrication methods such as selective laser  sintering and milling Manufacturing capabilities are rapidly changing and offer engineering levels   of precision and accuracy, Improved communications by allowing the clinician to view and approve  the design before manufacturing Improved alternatives to RPD materials Restricted by its high cost and   accessibility

29. T he block-out process is a   simple click to eliminate undesirable undercuts and locate des i rable undercuts according to depth chart on the right The 3Shape virtual surveyor enables a   technician to precisely locate the desired path of insertion when      digitally designing a removable partial denture framework. DIGITAL MANUFACTURING OF RPD

30. A digitally designed removable partial denture framework is  virtually created  and ready to add sprues for  perfactory   pattern printing.

31. Sprues are placed throughout the mandibular virtual framework preparing for additive perfactory pattern printing Maxillary is virtually designed as waxed framework with support bar

32. The  CadBlu  3D Systems inkjet printed  pattern is another option with a  soIid   wax sprue base.​ Mandibular and maxillary perfactory  printed patterns  on resin plate.​ Envisontec   perfactory  maxillary partial  pattern after the sprues have been removed and smoothed leaving the support bar for spruing to invest  then cast

33. The  Envisiontec  maxillary pattern printed with ​ perfactory  EC 1000 resin An intanglio view of the same maxillary 3D systems inkjet printed pattern

34. The multiple  Envisiontec ​ perfactory  printed patterns are  sprued  in one ring.​ The mandibular RPD framework is printed using Envisiontec additive perfactory EC 1000 resin

35. Casting of four  perfactory  RPD  framework patterns at  once.This  casting technique improves  efficiency and productivity for  investing, burn-out, and casting procedures.​ ​ The finished and  poIished  RPD frameworks from digitally  designed and computer-aided manufactured printed  patterns.​​

36. RAPID PROTOTYPING Rapid prototyping is a group of technique used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design (CAD) data. Additive manufacturing Substractive  manufacturing Frequent Rapid prototyping technologies that are adopted in dental practice Stereolithography  (SLA) Inkjet-based system (3DP) Selective laser sintering (SLS) and Fused deposition modeling (FDM)

37. PEEK MATERIAL Polyetheretherketone (PEEK) is a linear, aromatic, semi-crystalline thermoplastic, high performance polymer recently used in dentistry. It can be used as a framework material for metal-free fixed dental prosthesis , removable dental prosthesis, implant supported fixed prosthesis, implant- retained overdentures. Different surface modifications have allowed PEEK to bond with various luting agents.

38. PEEK MATERIAL IN RPD C an be manufactured by Conventional lost wax technique  CAD-CAM

39. ADVANTAGES OF PEEK RPD High biocompatability   Good mechanical properties High temperature resistance Chemical stability Due to a 4GPa modulus of elasticity, it is as elastic as bone and can reduce stresses 

40. The retentive force of  BioHPP  clasps could be a matter of concern. PEEK clasps offer a lower- retentive force than metal clasps. Properly designed PEEK clasps with an undercut of 0.5 mm could provide adequate  retention for  clinical use. BioHPP  clasps are gentler to the enamel and porcelain restorative  materials than conventional Cr--Co clasps are Clasps made of  BioHPPresult  in healthy periodontium, especially in cases of tissue  proximity due to the material's low plaque affinity properties.

41. CAD CAM CONSTRUCTED PEEK FRAMEWORK OF KENNEDY CLASS Ī RPD

42. IMPLANT ASSISTED RPD'S Improve support, retention, and stability of the prosthesis while maintaining alveolar height in the region where the implant is placed. Improve the oral health quality of life for patients. Benefit of it is significant in distal extension scenarios (Kennedy class  I and  II), as it  efficiently serves to improve support creating a tooth- supported situation (Kennedy class III). Minimizes the potentially damaging class I lever force that is placed on  the distal abutment tooth during function.

43. Economical and beneficial rehabilitation that significantly improves patient satisfaction

44. The preferred location of the implants may be different depending on the  purpose they will serve and bone availability. If extensive augmentation procedures were required to allow, implant Placement it is questionable as to the advantage the patient would receive. When used to improve retention, implants can provide the advantage of eliminating a  visible clasp when placed in the anterior region of the edentulous span. Anteriorly placed implant may  improve esthetics by eliminating a  visible retainer clasp.

45. To increase support, many clinicians advocate placing an implant in the  distal region to replace the missing distal abutment and essentially convert  the  situation to a Kennedy class III scenario. An implant that is placed parallel to the path of insertion of the RPD will have a more favorable outcome with fewer prosthetic complications. More favorable stress distribution and dissipation along the  peri -implant bone with implants placed in the first molar position compared with  that of second molar and premolar area. Closer proximity to distal abutment tooth helped with decreasing the stress placed on the PDL   fibers of the distal abutment tooth

46. In a patient based outcomes  study,jensen  and colleagues found that  implants significantly improved patient satisfaction and quality of life, and more  patients preferred the implant in the molar region over the premolar region Another debate regarding IARPD prosthodontic practices is the preferred  retention system. One study compared Stern ERA ( SterngoId,Attleboro ,  MA, USA) and O-ring attachments in a 2D finite element model by inducing axial  and oblique forces. The authors demonstrate that the ERA attachment system had more  favorablestress  distribution and was therefore the preferred system in  IARPD cases. Locator and housing systems seem to be the most widely used attachment system in IARPD. Ramachandran A, Agarwal KK, Chand P, Ramashanker , Singh RD, Gupta A. Implant- assisted removable partial  denture:An  approach to switch Kennedy Class I to Kennedy Class III

47. A recent in vitro study evaluating and comparing the strain around  abutment teeth found ball attachment to have the lowest strain,  followedby  the locator housing and the magnetic system. The highest strain was observed in the control group with a distal RPD  without any  impIant.Although  the axial loading of this study is a  limitation and does not reflect the complexity of the masticatory forces. It provides evidence that implant improve the strain of the RPD  abutment teeth with any attachment system Ramachandran A, Agarwal KK, Chand P, Ramashanker , Singh RD, Gupta A. Implant- assisted removable partial  denture:An  approach to switch Kennedy Class I to Kennedy Class III

48. NANOTECHNOLOGY Nanoimpression materials  Addition silicone vinyl  polysiloxane  impression material when integrated with nanofillers provide the following advantages. Better flow Improved hydrophilic properties Lesser voids at the margins High tear strength Resistance to  distorsion  & heat Snap set- reduces error by micromovement Trade name: Nanotech Elite H-D

49. NANO DENTURE BASE RESIN Titanium  dioxide  (TiO2), Ferric  oxide  (Fe2O  3)  nanoparticles  when added  as  pigments  in  PMMA  provide  color  of  the  gingiva. Low  porosity  and  prevents the  adherence  of  Candida  albicans . Addition of  carbon nanotubes  provides  superior  strength.

50. ​ NANOPARTICLES PROPERTIES ​ AI2O3 NPs ​ Thermal stability, flexural strength, water sorption, solubility, and biocompatibility ​ ZiO2 NPs ​ Impact strength, flexural strength and radio-opacity, Compressive strength, fatigue strength, fracture toughness and hardness as well as color properties ​ Zirconia nanotubes ​ Flexural strength ​ Silver NP ​ Antifungal properties,thermaI conductivity, and compressive strength, non cytotoxic, viscoelastic properties ​ TiO2 NPs ​ Flexure strength, fracture toughness, and hardness, Impact strength, water sorption,  and solubility                      Nano-carbon Impact  strength  and  flexural strength.

51. NANO COMPOSITE DENTURE TEETH​ Possesses unique characteristics in terms of    homogenicity  as the material  contains nanosized inorganic fillers that are well dispersed without agglomeration in the matrix.​ Stain resistant and harder than other commercially present denture teeth​ Wear resistant​

52. In 1987, the T-Scan Occlusal Analysis system ( Tekscan ,  Inc ) was developed by the Chairman of Prosthodontics of Boston University at that time, Professor William L. Maness in partnership with M.I.T.54. T Scan System is a computerized device that consists of I) hand-held device with flat U-shaped pressure-measuring sensor (60 pm thick, consists of an XY coordinate system with I SOO sensitive receptor points made of conductive ink, and is subject to elastic deformation) 2) computer software T-SCAN OCCLUSAL ANALYSIS SYSTEM

53. It is designed to obtain reliable measurements of occlusal  biting forces on dual teeth by analyzing occlusal forces  quantitatively. When the patient bites on the sensor, the electrical resistance of the conductive sensor is lessened since the force applied compresses  the particles together; this is recorded as quantitative force data.

54. APPLICATIONS Natural dentition with occlusal disturbances Implant placement, orthodontics Temporomandibular disorders, myofacial pain Prosthodontics (checking for high points and excessive contact locations) Patient education (treatment acceptance, improve longevity, enhanced comfort, eliminate extra visits) Occlusal diagnosis and equilibration

55. Underappreciated compared with FPDs or dental implant therapy! Problems associated with wearing an RPD and concerns with comfort. esthetics, function, and maintenance of  oraI   hygiene. It is the clinician's responsibility to fabricate a well-fitting RPD that maximizes support and framework design while satisfying the patient's realistic expectations for function and esthetics.- Maintenance and oral hygiene habits must also be emphasized. Even with the advent of new materials and RPD design concepts, techniques and materials used in their fabrication process have seen minimal change. Therefore RPD research more than ever needs to investigate new design principles to follow the development of new materials such as polymer frameworks and advance technologies including digital design and production. CONCLUSION- future needs in RPD

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