• In eccentric jaw movements, it is important not to

have contact on the implant-retained restoration.

Whenever possible, disclusion is preferred over the

natural canine.

• Whenever possible, the implant should be placed in

the middle of the edentulous crest of the bone.

FIGURE 35-4 Greater crestal bone loss occurs when

angulated abutments are given.

Implant failures and their management

Failures in implants can be classified as follows:

Failures in implants related to surgery and initial

healing period:

(i) Mobile fixtures

(ii) Mucosal fixtures

Failures in implant related to abutment connection

and initial loading:

(i) Abutment loosening

(ii) Occlusal factors

(iii) Screw loosening or cement failure

Failures in implants detected during follow-ups:

(i) Wear or breakage of the components

(ii) Soft tissue complications

(iii) Exposed implant threads

(iv) Fracture of abutment screw

(v) Fracture of fixture

(vi) Loss of implant

Failures in implant due to bacterial-induced factors:

(i) Poor oral hygiene of the patient

(ii) Retention of cement in the subgingival area

(iii) Macroscopic gaps between the implant components subgingivally

(iv) Marked inflammation, exudation and proliferation of the soft

tissues

Failures in implants related to initial healing

period

Mobile fixtures: If primary stability is not achieved during implant

placement, the fixture is primarily unstable and this prevents

adequate osseointegration.

• Overheating of bone during placement or failure to

achieve primary stability can result in loss of

osseointegration.

• It can be managed by placing a standard length

implant with bigger diameter, if possible.

• Implant failure rate in smokers is almost twice as

that of the nonsmokers.

• The patient is advised to quit smoking at least

during the first week of implant placement.

Mucosal fixtures: It can occur due to defective flap adaptation, suture

remnant granulomas or decubitus ulcer below the denture.

• It can be managed by excision of the perforation

site, flap mobilization, resuturing and proper

adjustment of the denture.

Failures in implants related to abutment

connection and initial loading

Abutment loosening: It can occur due to repeated loading of the

implant during chewing cycles or due to any parafunctional habits

of the patient.

• It can be managed by relieving any premature

occlusal contact and adequately tightening the

abutment screw.

Occlusal factors: Factors which can lead to implant failures are:

• Patient having parafunctional habits

• History of breakage of the superstructure or

retaining screws

• An angular pattern of bone loss

• Too few implants to replace missing teeth

• Excessive cantilevering

Screw loosening or cement failure: This can occur due to ill-fitting

prosthesis or excessive loading.

• Screw loosening can also occur, if the arch form is

not maintained.

• The causative factors should be eliminated to

correct the problem.

• If there is repeated incidence of screw loosening, the

screw should be replaced.

Failures in implant detected during follow-ups

Wear or breakage of the components: The common cause of wear or

breakage of components is ill-fitting prosthesis.

• Broken component is replaced and the ill-fitting

prosthesis is remade.

Soft tissue complications: The mucosa surrounding the abutment

should be checked for any inflammation.

• It may be caused due to poor implant positioning.

• The soft tissue is checked for increased probing

depth, soft tissue proliferation, bleeding, exudates

or tenderness.

• The area is examined radiographically to determine

the loss of bone or loss of integration.

• Soft tissue complications may require surgical

correction.

• If there is adequate attached gingiva, simple

excision is given.

• A loosely tightened abutment screw may cause the

formation of the granulation tissue at the

abutment–fixture connection.

• The granulation tissue is removed once the

abutment is unscrewed.

• After the removal of granulation tissue, the

abutment screw is adequately tightened.

Exposed implant threads: It may occur due to horizontal bone loss.

• There may be soft tissue proliferation over the

exposed threads.

• At the time of placement, the implant is placed deep

enough.

• Proper oral hygiene maintenance is important.

• There may be a need for periodontal therapy to

create attached gingiva by free mucosal or skin

grafts.

Fracture of abutment screw: Ill-fitting prosthesis or overloading of

implant is common cause for fracture of the abutment screw,

although the incidence is low.

• The fractured abutment screw is first retrieved and

then the cause is evaluated.

• New properly fitting prosthesis is constructed and

the broken screw is replaced with the new one.

Fracture of the fixture: Progressive horizontal bone loss is an

indication for stress concentration which can result in fracture of the

fixture over a period of time.

• The fractured fragment is removed using a small

diamond cutter.

• The area is inspected after removal of the fragment

and a new long abutment is placed.

• The junction of the abutment and the fixture is

checked for intimate fit using a radiograph.

Loss of implant: This may occur due to rapid horizontal and vertical

bone loss.

• The cause is evaluated and then treated first.

• After stabilization, another implant next to the site

is placed.

Peri-implantitis

Peri-implantitis is defined as ‘inflammation around the dental implant,

usually the dental abutment’. (GPT 8th Ed)

The inflammation occurs at the soft tissue implant interface. The

clinical signs of inflammation in the peri-implant soft tissues are:

• Gingivitis

• Suppuration

• Soft tissue oedema

• Bleeding

• Increased pocket depth

Aetiology

• Plaque accumulation in peri-implant mucosa

• Calculus

• Occlusal trauma

Diagnosis

• Periapical and vertical bitewing radiographs are helpful in

diagnosis.

• Plastic periodontal probe is used to assess the gingival health and to

monitor the pocket depths.

• No bleeding occurs on probing around implants because more rapid

breakdown occurs around implants in patient having poor oral

hygiene.

• Crestal bone loss with loss of perimucosal seal may occur.

• Mobility of implant can occur.

• Changes in the biochemical configuration of the crevicular fluid

may indicate implant failure.

Prevention

• Good oral hygiene maintenance

• Patient education

• Proper use of oral hygiene aids

• Chlorhexidine mouthwash

• Plastic or titanium instruments used to remove plaque and calculus

Management

• Nonsurgical treatment is used by proper plaque control, oral

hygiene instructions, use of chlorhexidine mouthwash, treatment

with citric acid and sodium hypochloride to remove bacterial

endotoxins.

• Surgical methods used for treating peri-implantitis are

mucogingival therapy, open debridement, apically positioned tissue

grafting, guided tissue regeneration and removal of implant.

• Implant is removed only in rare cases.

Immediate loading of implants

Immediate loading refers to a nonsubmerged implant which is placed

in single-stage surgery and is loaded with the provisional restoration

in the same appointment or shortly thereafter.

Immediate loading is a technique in which implants are restored, and

thus loaded at the time of the placement.

Types of immediate loading

Immediate functional loading

• Temporary restoration fitted on the same day as surgery and is in

occlusion.

• Patient is advised soft diet.

Immediate nonfunctional loading

• Temporary restoration fitted on the same day as surgery but is not

in occlusion (Fig. 35-5).

• Patient is advised soft diet.

FIGURE 35-5 Immediate functional loading.

Rationale for implant immediate loading

• Minimizes thermal injury and surgical trauma

• Acceleratory phenomenon of bone repair

• The interface is the weakest, at risk of overload at 3–6 weeks after

insertion

• Temperature: 38–41°C (M. Sharawy, C.E. Misch, N. Wellner, 2002)

and not above this range during osteotomy

• Slow intermittent pressure with irrigation and usage of sharp drills

• To reduce the risk of fibrous tissue formation

• To minimize woven bone formation and promote lamellar bone

maturation

Advantages

• It saves time and cost.

• It preserves alveolar bone; biostimulation occurs, so ridge height

and width are maintained.

• Aesthetic results can be obtained.

Disadvantages

• Case selection would be difficult.

• It may need soft tissue and hard tissue augmentation at a later date.

Key Facts

• In implant-retained overdenture for completely edentulous patient,

balanced occlusion or lingualized occlusion is given.

• In full fixed arch implant-supported bridges, there should be

simultaneous contact on the anterior and posterior teeth in centric

relation with anterior group function and multiple contacts in

eccentric jaw movements.

• Guided bone regeneration is used for the treatment of localized

ridge defects and to regenerate bone in dehiscence and

fenestrations.

• During osteotomy, care should be taken that the bone should not be

heated above 47ºC, as this will lead to bone cell death.

• Oil rig style bridge is made of standard cylindrical abutments

which are joined together with a composite resin bar used mostly in

the lower arch where aesthetics is not a primary concern.

• Misch occlusal analyser is used to evaluate the occlusal plane of the

patient before the restoration of the opposing arch.

• Minimum crown height space needed for the fixed implant

prosthesis is 8 mm.

• The distance from the centre of the most anterior implant to a line

joining the distal aspect of the two most distal implants is called the

anteroposterior distance or (A-P spread).

• Greater the A-P spread, more favourable is the situation of the

posterior cantilever.

• The tip of the osteotomes is usually concave and blunt so as to

minimize the chances of tearing the Schneiderian membrane

during sinus lift procedures.

• In group function occlusion, there is contact of all the teeth on the

working side and there is no contact on the balancing side.

• Shim stock is the most accurate method of checking occlusion for a

fixed prosthesis.

• Anterior mandible is the ideal location for placement of implants.

• The intraoral sites for harvesting bone for autogenous graft are

maxillary tuberosity, mandibular symphysis, mandibular ramus or

third molar region.

• Recently introduced zirconia abutments provide excellent

aesthetics.

• The implant should be placed at least 2 mm longer than the tooth

socket for good primary stability.

Question bank

Section I: Complete dentures

1. Write problems associated in cases of having single complete

dentures opposing natural remaining teeth.

2. Discuss dentogenic concept with reference to aesthetics in complete

denture prosthodontics.

3. ‘Establishing and verification of correct vertical jaw relations for

complete dentures always poses a challenge to prosthodontist’.

Discuss.

4. Write causes and methods of correcting occlusal discrepancies in

processed complete dentures.

5. Discuss the advantages and shortcomings of balanced occlusion in

complete dentures.

6. Describe the techniques of producing balanced occlusion.

7. Describe Bennett movement. How are these incorporated in various

articulators?

8. Describe the biological aspects to be considered during complete

denture impression making.

9. Discuss the importance of centric relation in complete dentures.

10. Describe the methods of obtaining centric relation for the

edentulous patient.

11. Discuss the usefulness of facebow. Give a brief historical account

of the origin and development of facebow.

12. Discuss the effects of complete dentures on hard and soft tissues of

the oral cavity with special reference to measures to minimize it.

13. Discuss the rationale for selecting artificial teeth for edentulous

patients.

14. Give an account of the evolution of artificial posterior tooth form.

15. Give an account of factors affecting occlusion in complete

dentures.

16. Discuss the evolution of articulators.

17. Discuss the significance of ‘hinge axis’ theory of mandible. Give

your comments on its clinical importance in prosthodontics.

18. Discuss the objectives and procedure of selective grinding in

complete dentures.

19. Discuss aesthetics and phonetics in complete denture prosthesis.

20. Discuss the factors for retention of complete dentures with a

special reference to posterior palatal seal.

21. Discuss the role of mandibular rest position as it relates to

complete denture prosthodontics.

22. Discuss how facial and functional harmonies are achieved during

arrangement of artificial teeth for complete dentures.

23. Discuss the muscle tone and its relationship to vertical dimension.

24. Discuss the importance of anterior guidance during aesthetic

restoration.

25. Define patient education. Discuss the role of patient education and

patient motivation in the success of a complete denture therapy.

26. Describe the nutritional factor in complete denture patient.

27. Write briefly the procedure of making an impression of flabby

ridge.

28. Discuss the treatment of abused tissues in complete denture

construction.

29. Define vertical jaw relations. What are the different methods by

which vertical jaw relations can be recorded?

30. Write a note on neutral zone.

31. Describe the peripheral structures affecting mandibular dentures.

32. Discuss the degenerative changes in the oral cavity on account of

ageing and its effects in the fabrication of complete dentures.

33. Discuss the preprosthetic surgery in the treatment of completely

edentulous patient.

34. Write a short note on masticatory efficiency of complete dentures.

35. Write a short note on denture cleansers.

36. Discuss posterior palatal seal as an indispensable clinical step in

maxillary complete dentures. Describe the methods of recording

posterior palatal seal.

37. Discuss the theories of impression making in complete dentures.

38. Discuss the critical role played by border moulding lingual flange

of the special tray in the stability of mandibular complete dentures.

39. ‘Troubleshooting in complete dentures prosthesis’. Discuss the

statement and your management.

40. ‘Immediate denture service designed to preserve oral structures’.

Discuss the merits and demerits of this statement.

41. Write importance of incisive papilla in the arrangement of anterior

teeth.

42. Discuss the gothic arch tracings as related to the various

movements of lower jaws with special reference to the development of

balanced occlusion.

43. What are jaw relations? How will you record the following

relations with maximum accuracy: (i) orientation of the plane of

occlusion, (ii) vertical dimension of occlusion (VDO) and (iii) centric

relation.

44. Define centric relation. Describe the technique of registering

centric relation in clinic for an edentulous case.

45. Write a short note on age changes in edentulous patients.

46. Write a short note on special tray for edentulous mouth.

47. Describe briefly about the sequelae of wearing complete dentures.

48. Describe briefly about the anatomy of maxillary denture-bearing

area.

49. Write a short note on residual ridge resorption.

50. Write a short note on alveololingual sulcus.

51. Define retention, stability and support. Describe the biological,

mechanical and physical factors which promote these qualities in

complete dentures.

52. Define impression. Classify the different types of impression in the

field of dentistry.

53. Differentiate between the mucostatic and mucocompressive

impression techniques.

54. Discuss the statement ‘artificial denture can be a boon to the

patient, but artificially looking denture a curse’.

55. Explain in detail about the anatomy and physiology pertaining to

the maintenance of physiological rest position of the mandible with a

detailed note on muscle tone, muscle spindle and myotatic reflex.

56. Explain the significance of centric and eccentric jaw relations. Give

a critical evaluation of the methods to record centric jaw relations.

57. Explain the methods of making interocclusal records and

establishing the centric relations of partially edentulous conditions.

58. Discuss the rationale and technique of relining complete dentures.

59. Discuss the movements and the various reference positions of the

mandible.

60. Describe the rationale and technique of ridge augmentation for

complete dentures.

61. Write a short note on the evaluation of methods to obtain vertical

space for complete dentures.

62. Write a short note on bar designs in overdentures.

63. Write a short note on Bennett movement.

64. Write briefly about the theories of occlusion.

65. Critically evaluate the various posterior tooth forms with respect

to balanced occlusion and masticatory efficiency.

66. Write a short note on border moulding of lingual crescent.

67. Write a short note on reduction of residual ridge.

68. Write a short note on semi-adjustable articulators in practice.

69. Discuss the statement ‘temporomandibular joint controls

biomechanical phase of prosthetic rehabilitation’.

70. Discuss the recent trends in prosthodontics research in complete

denture prosthodontics.

71. Describe the importance of characterization of the denture base

and anterior teeth with reference to the aesthetics in complete

dentures.

72. Discuss the concept of ‘overdenture philosophy’ in preservation of

the residual alveolar ridges.

73. How do you select posteriors for edentulous patients with

moderate ridges?

74. Write short note on resilient permanent soft liners?

75. Define denture aesthetic. Discuss its importance in complete

denture prosthodontics.

76. Describe the types of denture teeth on the basis of materials and

morphology.

77. Write about the selection of anterior teeth in complete denture

prosthodontics.