1. PERIRADICULAR LESIONS of pulpal origin

2. Definition
Apical periodontitis is an inflammatory disorder of the periradicular tissue caused by a persistent microbial infection of the root canal system of the affected tooth

3. In other words
Apical periodontitis (AP) is a host response to infections by microbes and the subsequent inflammatory response

4. Apical periodontitis includes the infection and inflammation of the lateral and furcal locations.

5. The root canal and the pulp chamber are niche environments for the causative organism

6. Biofilms
Bacteria form biofilms and these pathological bacteria are embedded in the biofilms
Biofilms protect the bacteria from antibiotic attack and make them a X 1000 more resistant to the effects.

7. Infection portals Pulp becomes infected by Carious exposure
Leaking restorations
Dentinal tubules
Fractures or cracks

8. Inflammatory response
The antigens and bacterial toxins percolate into the surrounding tissue

9. Most likely anaerobic bacteria invade that provoke an inflammatory response i.e.
Chemotaxis
Enzymatic breakdown with the subsequent release of antigens

10. This response destroys much of the peripical tissue
The host mounts a immune response consisting of several classes intercellular messengers and antibodies.
This response destroys much of the peripical tissue
This results in the formation of various types of apical periodontal lesions.

11. The defence reaction minimises the spread of infection.
It cannot eliminate the microbes entrenched in a necrotic root canal , and biofilm.

12. Treatment is required via surgical or non surgical endodontic therapy as biofilms protect the bacteria from the host defenses.

13. Classification of AP
Apical periodontitis is an inflammatory disease and classification is based on symptoms , aetiology or histopathology.

14. Nomenclature and Classification
Numerous terms are used such as
Apical granulomas
Apical cysts
Periapical lesions
Periapical osteitis

15. Three main clinical groups
symptomatic(acute) apical periodontitis
asymptomatic(chronic) apical periodontitis
apical abscess

16. Symptomatic(acute) Apical Periodontitis
The principal causes are irritants diffusing from an inflamed or necrotic pulp.
Negative vitality test not always accurate
Pain!!!(WHY?)

18. Asymptomatic(chronic) Apical Periodontitis
Preceded by an acute episode
lesion frequently develops and enlarges without any subjective signs and symptoms
Causes
Inadequate endodontic procedure
Low grade pathogenicity/ irritant
Pathosis is a long-standing “smoldering” lesion

19. Asymptomatic(chronic) Apical Periodontitis(Cont)
Non vital respnse
Radiographic evidence is the key
Called a peri radicular granuloma or periradicular cyst.
Periradicular Granuloma. Nobuhara and del Rio(JOE1993;19:315) showed that 59.3% of the periradicular lesions were granulomas, 22% cysts, 12% apical scars, and 6.7% other pathoses

20. Histologically, the periradicular granuloma consists predominantly of granulation inflammatory tissue with many small capillaries, fibroblasts, numerous connective tissue fibers, inflammatory infiltrate, and usually a connective tissue capsule

21. Apical periodontitis (granuloma) with contained epithelium
Apical periodontitis (granuloma) with contained epithelium. Epithelial cells of periodontal ligament have proliferated within new inflammatory tissue. The epithelium tends to ramify in a reticular pattern (straight arrow) toward receding bone. It also may, as in this case, apply itself widely to the root surface (curved arrow). Infiltration of epithelium by round cells is everywhere apparent. Human tooth. Reproduced with permission from Matsumiya S.Atlas of oral pathology. Tokyo: Tokyo Dental College Press; 1955.

22. Periradicular Cyst.
Periradicular cyst shows a central cavity lined by stratified squamous epithelium
This lining is usually incomplete and ulcerated
The lumen contains a pale eosinophilic fluid and occasionally some cellular debris

24. Apical cyst with marked inflammatory overlay
Apical cyst with marked inflammatory overlay. Round cells permeate both the epithelium and the connective tissue immediately deep to it. Spaces indicate where crystalline cholesterol has formed within the cyst. Bone formation is evident (arrow). This may reflect narrowing of the width of the connective tissue zone, as occurs in some apical cysts. Human tooth. Reproduced with permission from Matsumiya S. Atlas of oral pathology. Tokyo: Tokyo Dental College Press; 1955.

25. Condensing Osteitis
Inflammation of periradicular tissues of teeth usually stimulates concurrent osteoclastic and osteoblastic activities.
Osteoclastic (resorptive) activities are usually more prominent than osteoblastic (formative)
Condensing osteitis is associated with predominant osteoblastic activity

26. Condensing Osteitis (CONT)
attributable to a special balance between host tissues and the root canal irritants.
Condensing osteitis, or chronic focal sclerosing osteomyelitis, is a radiographic variation of AAP and is characterized as a localized overproduction of apical bone.
usually observed around the apices of mandibular posterior teeth with pulp necrosis or chronic pulpitis

27. Condensing Osteitis (CONT)
The tooth associated with condensing osteitis may be asymptomatic or sensitive to stimuli.

28. Apical condensing osteitis that developed in response to chronic pulpitis. Additional bony trabeculae have been formed and marrow spaces have been reduced to a minimum. The periodontal ligament space is visible, despite increased radiopacity of nearby bone.

29. APICAL ABSCESSES
An abscess is a localized collection of pus in a cavity formed by the disintegration of tissue
Apical abscesses can be divided into symptomatic or asymptomatic conditions

30. APICAL ABSCESSES
Symptomatic Apical Abscess A sudden egress of bacterial irritants into the periradicular tissues
severe sequelae, acute osteitis and cellulitis.
Accompanied by exudate formation within the lesion
May occur without any obvious radiographic signs
infection and rapid tissue destruction arising from within AAP( Phoenix abcess)

31. APICAL ABSCESSES/clinical
May or may not have swelling
Swelling may be localized or diffuse
Varying degrees of sensitivity to percussion and palpation
No pulp reaction to cold, heat, or electrical stimuli as the involved tooth has a necrotic pulp
Radiographic features of the SAA vary from a thickening of the periodontal ligament space to the presence of a frank periradicular lesion

32. Radiographic features of symptomatic apical abscess
Radiographic features of symptomatic apical abscess. The patient developed sudden symptoms of pain and facial swelling. Radiographically, a lesion is apparent apically to the maxillary left lateral incisor, that did not respond to vitality tests, confirming pulpal diagnosis of necrosis.

33. Asymptomatic Apical Abscess
Asymptomatic apical abscess (AAA), also referred to as suppurative apical periodontitis, is associated with a gradual egress of irritants from the root canal system into the periradicular tissues and formation of an exudate. The quantity of irritants, their potency, and their host resistance are all important factors in determining the quantity of exudate formation and the clinical signs and symptoms of the lesion. Asymptomatic apical abscess is associated with either a continuously or intermittently draining sinus tract.

36. WHO uses a symptomatic classification based on clinical signs
Acute apical periodontitis
Chronic apical periodontitis
Periapical abscess with sinus
Periapical abscess without sinus
Radicular cyst

37. Histopathological classification (Nair PNR: Pathology of Apical Periodontitis)
In order to understand the disease process a histopathological classification is used:
The distribution of pathological cells in the lesion
Presence or absence of epithelial cells
Transformation of a lesion into a cyst
The relationship of the cyst cavity to the affected root

38. Histopathological classification
Acute apical periodontitis - an acute inflammation of endodontic origin . A distinct focus of neutrophils have to be present
Primary or initial short lived inflammation in a healthy periodontium.
secondary or exacerbating when an acute episode occurs on a preexisting chronic lesion *also called a phoenix abcess

39. Histopathological classification
Established chronic apical periodontitis
Long standing inflammation
presence of granulomatous tissue
Cells are lymphocytes , plasma cells and macrophages
Lesion may be epithelialised or non-epithelialised

40. Histopathological classification
Periapical true cyst is an apical inflammatory cyst with a distinct pathological cavity completely enclosed in an epithelial lining so that NO communication to the root canal exists

41. Histopathological classification
A periapical pocket cyst is an apical inflammatory cyst containing a saclike epithelium lined cavity that is open and continuous with the root canal

42. Histopathologically the lesions of AP can be classified as acute, chronic ,or cystic .AAP may be (A.) primary or secondary(B) and is characterized by a focus of PMN, (C) major component are lymphocytes plasma cells and macrophages, (D) true cysts enclosing the lumina and pocket cysts (E)cavity is open to the root canal. Arrows indicate the direction of in which the lesion can change.

43. Important points Bacteria are anaerobes Bacteria have to be present
There has to be a portal for infection to occur i.e.
Caries
Clinical procedures
Fractures
Dentinal tubules

44. To treat or not to treat? Anatomic considerations Root shapes?
Can you remove infected hard and soft tissue
Give disinfecting agents access to the apical canal space
Create space for the delivery of medicaments and subsequent obturation
Retain the integrity of the radicular structures

45. To treat or not to treat? Is the tooth restorable?
Is there an adequate ferule, the amount of remaining tooth structure
Is root decay present
Vertical fractures
Post preparations in teeth
Anatomical positions of the tooth
Occlusal forces on the tooth

46. To treat or not to treat? Sclerotic canals
Restorative requirements of the tooth
Aesthetic requirements
Sclerotic canals

47. Surgical Posterior part of mandible Inferior dental nerve
Thickness of mandible
Mental foramen
Facial artery
PDL
Consider alternative

48. Surgical Posterior part of Maxilla Anterior maxilla / mandible
Sinus perforation with infected root fragments
Palatal access
Anterior maxilla / mandible
Long roots
Inclinations (mandible) and mental protuberance

49. Prepared teeth are anatomically more difficult to treat

50. Endodontic and periodontal relationships
Vascular connections exist between the pulp and periodontal ligament.
Pulp and periodontal problems are responsible for more than 50% of tooth mortality.
There is no doubt that an interrelationship exists in diseases that affect both the pulp and periodontium

51. When the pulp necroses for whatever reason products from pulp degeneration reach the supporting periodontium. This is characterised by bone loss, tooth mobility , and sometimes sinus tract formation.
Apically if this occurs , a periradicular lesion forms which can extend crestally (Reverse pocket is formed)

52. Periodontal disease may have a gradual , atrophic effect on the pulp.
Periodontal treatments such as deep root planing or curettage, or localized irritants e.g. acids may cause pulpal irritation.is

53. In addition lateral or accessory canals with 28% at the furcation.
Apical foramina have been shown to be the most direct root of communication to the periodontium.
In addition lateral or accessory canals with 28% at the furcation.

54. Periradicular periodontitis
Acute, painful to biting or percussion, the vitality may or may not be positive. No periradicular radiolucency and widened PDL, Apical 1/3 of root
Chronic , no clinical symptoms, negative vitality test , periapical radiolucency , altered patient sensation

55. Periradicular abcess
Acute, sensitive to pressure and palpation, negative vitality test , increased mobility , increased pdl space, associated temperature
Chronic, no clinical symptoms, no vitality response periradicular radiolucency on radiograph, suppurative lesion(pus drainage )

56. Periodontal considerations
Channels exist between pulp and periodontal tissue
These include neural pathways, lateral canals dentinal tubules, palato-gingival grooves periodontal ligament alveolar bone , apical foramina and vascular and lymphatic pathways

57. Endodontic / Periodontic Relationships
Primary endodontic -lesions lateral aspects of the root sinus tract along the root – gutta-percha trace
Primary endodontic with secondary periodontal involvement –accumulation of plaque / calculus apical migration of tissue

58. Endodontic / Periodontic Relationships
Primary periodontal lesions -deposit in sulcus migrates apically. Vital pulp got to distinguish this from previous both look the same.
Primary periodontal secondary endodontic involvement-accentuated pain from lesion. Hard to separate from endo perio

59. Endodontic / Periodontic Relationships
True combined lesion- damage to pulp and periodontium at the same time that may coalesce classic ‘J’- lesion
Treatment can include the resection of roots (multirooted) , but lesions associated with cracked roots , older patients and posts. Regeneration procedures.

60. NONENDODONTIC PERIRADICULAR LESIONS
Got to differentiate between pulpal pathology and non-endodontic origins of alterations in bone morphology.
38 radiolucent lesions and other abnormalities of the jaws.Three of these lesions, dental granuloma, radicular cyst, and abscess, are categorized as being related to necrotic pulps. In addition,16 radiopaque lesions of the jaws, 3 of which, condensing osteitis, sclerosing osteomyelitis, and Garré’s osteomyelitis, are also related to pulpal pathosis
Never assume a radiolucency is pulpal pathology.

61. NONENDODONTIC PERIRADICULAR LESIONS
Lesions of the jaws categorized as odontogenic or nonodontogenic in origin
Odontogenic lesions arise from remnants of odontogenesis (or the tooth-forming organ), either mesenchymal or ectodermal in origin.
Nonodontogenic lesions trace their origins to a variety of precursors and therefore are not as easily classified.

62. Differentiating between lesions of endodontic and nonendodontic origin is usually not difficult. Pulp vitality testing, when done with accuracy, is the primary method of determination; nearly all nonendodontic lesions are in the region of vital teeth, whereas endodontic lesions are usually associated with pulp necrosis, giving negative vitality responses. Except by coincidence, nonendodontic lesions are rarely associated with pulpless teeth.

63. Odontogenic Cysts Dentigerous Cyst Lateral Periodontal Cyst
Odontogenic Keratocyst
Residual Apical Cyst.

64. Lateral periodontal cyst
Lateral periodontal cyst.Well-circumscribed radiolucent area in apposition to the lateral surfaces of the lower premolars (black arrows demarcate the extent of lesions). No clinical signs or symptoms were noted. Pulps tested vital.

65. Bone Pathology: Fibro-osseous Lesions
Periradicular Cemental Dysplasia
Osteoblastoma and Cementoblastoma
Cementifying and Ossifying Fibroma.

66. A, Periradicular cemental dysplasia (osteofibrosis), initial stage
A, Periradicular cemental dysplasia (osteofibrosis), initial stage. Pulps in both teeth are vital. B,
Transition to the second stage is developing. C, Biopsy of periradicular osteofibrosis, initial stage. Fibrous connective
tissue lesion has replaced cancellous bone.

67. Cementoblastoma. The lesion is a fairly well-defined radiopaque mass surrounded by a thin radiolucent line. It has also replaced the apical portions of the distal root of the first molar

68. Ossifying fibroma. The patient presented with pain
Ossifying fibroma. The patient presented with pain. The pulp was vital, indicating that this was not an endodontic pathosis. Root canal treatment was followed by root end removal and excision of the lesion. Biopsy confirmed the diagnosis

69. Odontogenic Tumors
Ameloblastoma.

70. Two examples of ameloblastoma
Two examples of ameloblastoma. A, Surgical specimen of infiltrating ameloblastoma of mandible. B, “Unicystic” ameloblastoma. This solitary lesion has displaced teeth much as an apical cyst would do. The teeth are vital.

71. Nonodontogenic Lesions
Central Giant Cell Granuloma.
Nasopalatine Duct Cyst
Simple Bone Cyst.
Globulomaxillary Cyst
Enostosis.

72. Malignancies
Carcinomas or sarcomas of various types are found in the jaws, rarely as primary but usually as metastatic lesions
Carcinoma. Generally found in older patients, involvement of the jaws (usually the mandible) is by metastasis from a primary lesion elsewhere
Carcinoma lesions of the jaw may also manifest pain and swelling, loosening of teeth, or paresthesia, similar to endodontic pathosis
Radiolucent jaw malignancies have been mistaken for periradicular lesions.

73. Radicular cyst 
Residual cyst 
Paradental and mandibular infected buccal cysts
Mandibular Infected Buccal Cyst   
Lateral periodontal cyst
Glandular odontogenic cyst
Odontogenic keratocyst
Gorlin syndrome