Tooth Loss

1. ToothLoss

2. The loss of teeth is the most common cause of a physiologic occlusion developing into a non-physiologic occlusion

3. In a healthy complete dentition, there is a an equilibrium of forces from lips, cheeks, tongue, neighboring teeth those help to maintain a relative stability of individual teeth

6. The loss of a single tooth may lead to drifting, tipping, rotation of neighboring teeth, and extrusion of opposite teeth.

7. Tipping • Tipping Rotation of a molar forward (mesially) or backward (distally) around its body mass axis called Center of Resistance

9. Drifting • All the teeth are held securely in the jawbone. • With no adjacent support the neighboring teeth begin to drift toward the area of the missing tooth

10. Disease, decay or trauma may lead to tooth loss. If a lost tooth is not immediately replaced, the surrounding bone begins to collapse and shrink

12. The amount of bone loss and the pattern of drifting will vary depending on the individual and the location of tooth loss.

13. The drifting of one tooth may lead to the drifting of several teeth, resulting in a significant amount of movement

15. Periodontal disease may begin to form after the teeth have drifted and erupted because it becomes difficult to properly clean the gums and reach all the pockets in those areas. This may lead to tooth decay, receding gums, and further tooth loss.

17. Migration of teeth Some potential consequences: • 1- Loss of mandibular first molar, meisal tipping of the mandibular second and third molars and the extrusion of the maxillary first molar.

18. 2-Loss of occlusal vertical dimension • 3-Opening of proximal contacts • 4-Uneven adjacent marginal ridges • 5- Development of “Plunger” cusps

19. 6-Food impaction • 7-Lack of functional cleansing of teeth These are less predictable because of individual variations

20. Example: • Age and time of tooth loss • Periodontal conditions • Inter cuspation of the teeth adjacent to the lost tooth and their antagonists

21. An epidemiologic study (Zarb et al ., 1978) showed that 20% of patients with tooth loss at an early age had subsequent closure of the ensuing space.

22. Occlusal conditions leading to or resulting from unilateral function represent significant deviations from the criteria of the “ optimal occlusion” Byron : 1969

23. An optimal occlusion is characterized by – • Chewing performed with equal ease on both sides • Bilateral stable occlusion contacts on most of the teeth in the intercuspal position

24. Bilateral stable occlusal contacts on posterior teeth in the retrusive range in the retruded contact position and a small distance between intercuspal position and retruded contact position in the mid sagittal plane

25. Even though the ability to adapt with in the masticatory system is great, the loss of even a single tooth may lead to occlusal instability and interferences with unfavorable consequences for occlusal function, chewing habits and oral hygiene

26. Other consequences of tooth loss • The more teeth are lost, the greater the risk of tipping, migration, extrusion, and attrition of remaining teeth and the loss of alveolar bone and occlusal vertical dimension

27. The more depleted the periodontal support, the greater the risk of trauma from occlusion • Teeth with markedly reduced periodontal support, occlusal trauma will not cause further destruction of the attachment apparatus, provided the plaque induced periodontal disease has been cured

28. Temporomandibular disorders and tooth loss • The diverging options about the influence of a reduced dentition on the masticatory system prompted to perform a study on the relationship between shortened dental arches and oral function

29. The results showed two patters of change in oral function. 1. Slow change until four occlusal units are left and then rapid change and 2. Progressive change without sudden change

30. Tooth loss and neuromuscular changes: • It is probably more accurate to emphasis the neuromuscular and functional sequelae of loss of posterior teeth.

31. In some individuals posterior tooth loss is well compensated by adaptive processes, while in others it may contribute to functional disturbances.

32. Natural Occlusion (organic) • Bilateral Posterior Centric Contact • Anterior Guidance • Mutually Protective Scheme of Occlusion

33. Complete Denture Occlusion Complete denture “dentition”also presents in a variety of forms, but also exhibit certain common characteristics

34. Complete Denture Occlusion • Bilateral centric contacts • Bilateral eccentric contacts (balance) to provide stability of the denture bases during function • Non-balanced monoplane occlusion

35. Complete Denture Occlusion • Because of compromises inherent in restoring the edentulous arch, complete denture tooth forms and arrangements (i.e. occlusion), should be designed to provide function and aesthetics while minimizing denture base tipping (lateral) forces

36. Fundamental differences of natural and complete denture occlusion 1. Sensory feedback mechanism 2. Derivation of : • retention • stability • support 3. Reaction of supporting structures to masticatory forces

37. 1. Sensory Feedback Precision of feedback is significantly compromised following loss of teeth and associated structures (periodontal ligament)

38. 2. Derivation of retention, stability and support for natural occlusion For natural dentition, retention, stability, and support are derived through the periodontium which provides;

39. Sensory feedback mechanism • Difference in reaction of supporting structures to masticatory forces • Differences in load transfer mechanism and physiology

40. Complete dentures receive their retention, stability, and support from the soft tissues overlying residual bone (ridges, buccal shelf, palate, etc.).

41. Denture Bearing Surface • Retention • Resistance to dislodgment forces in a vertical direction away from the bearing surface

42. Denture Bearing Surface • Stability • Resistanceto laterally oriented dislodgment forces

43. Denture Bearing Surface • Support • Factors of the Bearing Surface which resist forces in a vertical direction towards the bearing surface

44. 3. Reaction of supporting structures Natural occlusion Physiologic levels of tension results in alveolar bone apposition (such as that transmitted by loading the periodontal ligament through natural dentition)

45. Complete denture occlusion Non-physiologic compression as may occur under denture bases results in further residual ridge resorption (RRR

46. Summary • Mobile bases on mucosa • Teeth move as an unit • Malocclusion affects entire base immediately • Non-vertical forces affect all teeth and are traumatic • Incising affects all teeth attached to base • Bilateral balance is often desired for base stability • Decreased tactile sense Denture “Dentition” Natural Dentition • Retained in PDL • Units move independently • Malocclusion effects not immediate • Non-vertical forces affect only teeth involved and usually well tolerated • Incising doesn’t affect posteriors • Bilateral balance is rare • Tactile sensitivity

47. 9 aspects that influence Tooth Loss A study conducted by Al-Shammari et al., (Journal of Periodontology 2005; 76(11); 1910 – 1918) identified 9 major aspects that influence the condition of tooth loss. They are –

48. 1. Age 2. Male gender 3. Smoking 4. Lack of professional maintenance. 5. Inadequate oral hygiene 6. Diabetes Mellitus 7. Hyper tension 8. Rheumatoid arthritis 9. Anterior tooth type

49. Smoking and Tooth Loss: • Another study by M. Ojima et al (BMC Public Health 2008) provide evidence regarding the association between smoking and tooth loss among adults aged 20-39

50. Smoking rates differed greatly in men (53.3%) and women (15.5%). • The overall prevalence of tooth loss was 31.4% (31.8% men and 31.1% women).