Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PERI 326 > Unit 2 - Anatomy and Histology of Periodontium > Flashcards

Unit 2 - Anatomy and Histology of Periodontium Flashcards

1
Q

What are the four principal components of the periodontal (in order)?

A
  • Gingiva
  • Alveolar bone
  • Periodontal ligament
  • Cementum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does the word periodontium mean?

A

Tissues that invest and support the teeth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the mucous membrane lines the oral cavity?

A

Oral mucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a mucous membrane?

A

Lining of a body cavity that communicates with the external environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the four functions of the oral mucosa?

A
  • Protection
  • Sensation
  • Synthesis/secretion
  • Esthetics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the distinguishing feature of orthokeratinized epithelium?

A

No nuclei are present within the keratin layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the distinguishing feature of parakeratinized epithelium?

A

Some pyknotic nuclei are present within the keratin layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the distinguishing feature of nonkeratinized epithelium?

A

No keratin layer on the epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What tissue is the papillary layer made of?

A

Loose connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What tissue is the reticular layer made of?

A

Dense connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where structure does the lamina propria insert into?

A

Epithelial rete pegs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where is the submucosa located?

A

Located below the lamina propria, not part of the mucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What layer contains structures such as adipose tissue, glands, pacinian corpuscles, blood vessels, and nerves?

A

Submucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What structures does the masticatory mucosa cover?

A

Gingiva and hard palate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What structures does the lining mucosa cover?

A

Vermilion, buccal mucosa, lips, ventral surface of tongue, floor of mouth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What structures does the specialized mucosa cover?

A

Dorsum of the tongue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What mucosa covers the alveolar processes of the jaws and surrounds the necks of teeth?

A

Masticatory mucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the three functions of the gingiva?

A
  • Mechanical barrier
  • Chemical barrier
  • Microbial barrier
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the three divisions of the gingiva?

A
  • Marginal gingiva
  • Attached gingiva
  • Interdental gingiva
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What division of the gingiva can be separated from the tooth surface using a probe?

A

Marginal gingiva

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What division of the gingiva forms the tissue wall of the gingival sulcus?

A

Marginal gingiva

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What structure separates attached gingiva and the marginal gingiva?

A

Free gingival groove (aka marginal groove)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the two boundaries of the gingival sulcus?

A
  • Tooth surface
  • Free gingival epithelium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a normal probing depth?

A

1-3 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What structure roughly correlates to the bottom of the gingival sulcus in most healthy gingiva?

A

Free gingival groove (aka marginal groove)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Where is the attached gingiva located?

A

Tightly attached to the periosteum of underlying alveolar bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The facial aspect of the attached gingiva attaches to what structure?

A

Mucogingival junction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What does the mucogingival junction separate?

A

Attached gingiva from the alveolar mucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Is the alveolar mucosa made of keratinized or non-keratinized epithelium?

A

Non-keratinized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Is the free gingiva made of keratinized or non-keratinized epithelium?

A

Keratinized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Is the attached gingiva made of keratinized or non-keratinized epithelium?

A

Keratinized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Does the mucogingival junction remain stationary in adults?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Where is the interdental gingiva located?

A

Fills in the inter proximal spaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What epithelium is the facial interdental papilla made of?

A

Keratinized stratified squamous epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What epithelium is the lingual interdental papilla made of?

A

Keratinized stratified squamous epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What epithelium is the col space of the interdental papilla made of?

A

Non-keratinized stratified squamous epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

The shape of the interdental gingival papillae correlates with what?

A

The shape of the teeth and embrasures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What can attach at the frenums?

A
  • Muscles
  • Connective tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Does the lamina propria contain blood vessels and nerves?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What layer does the masticatory mucosa lack?

A

Submucosa layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the cell renewal time of the oral outer epithelium?

A

10 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

The oral outer epithelium is made out of…

A

Orthokeratinized and parakeratinized epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

The sulcular epithelium is made out of…

A

Non-keratinized epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What does the lamina propria contain in the sulcular epithelium?

A

Gingival fiber bundles and loose connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

The junctional epithelium is made out of…

A

Non-keratinized epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What is the cell renewal time of the junctional epithelium?

A

4 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Why is it important for the junctional epithelium to have a fast cell renewal time?

A

Important to heal quickly to keep the tooth attached to the gingiva

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

The junctional epithelium varies in length from…

A

0.25 to 1.35 mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Cells of junctional epithelium immediately adjacent to the tooth are attached to the tooth surface by what two structures?

A
  • Hemidesmosomes
  • Internal basal lamina
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Cells of the junctional epithelium adjacent to the lamina propria are attached by what structure?

A

External basal lamina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

How many basal laminae does the junctional epithelium have?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Are the majority of epithelial cells of the gingiva keratinocytes, melanocytes, Merkel cells, or Langerhans cells?

A

Keratinocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What is the function of melanocytes?

A

Synthesis of melanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What is the function of Merkel cells?

A

Tactile sensory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Where does mitosis of keratinocytes take place?

A

Basal layers of the epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What is the function of Langerhans cells and lymphocytes?

A

Immune response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Where do “old” keratinocytes eventually go?

A

Migrate to the surface of the epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

When does differentiation of keratinocytes occur?

A

During cell migration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What does the differentiation of keratinocytes result in?

A

Keratinization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Starting where mitosis of keratinocytes occurs, what layers of the epithelium do they migrate through?

A
  • Basal layer/stratum basale
  • Prickle layer/stratum spinosum
  • Granular layer/stratum granulosum
  • Keratinized layer/stratum corneum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What structure do keratinocytes lose as they migrate towards the surface?

A

Nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

How quickly does keratinocyte cell renewal occur?

A

10 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is a desmosome?

A

Cell structure specialized for cell-to-cell adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is acantholysis?

A

Loss of intercellular attachments/desmosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What produces physical pigmentation?

A

Melanin from melanocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Where are melanocytes found?

A

Basal and prickle cell layers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What cells acquire antigens, transport to local lymph nodes, present to T-cells, and initiate immune response?

A

Langerhans cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What are Merkel cells innervated by?

A

Mechanosensory neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What is the basement membrane?

A

Acellular layer between the epithelium and underlying connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

What is the basement membrane made out of?

A
  • Basal lamina
  • Lamina reticularis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What is the basal lamina made out of?

A
  • Lamina lucida
  • Lamina densa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What is the primary cell in connective tissue?

A

Fibroblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

What two layers of connective tissue is the lamina propria located in?

A
  • Papillary layer
  • Reticular layer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What 3 things is connective tissue composed of?

A
  • Fibroblasts, 5%
  • Collagen fibers, 60%
  • Maxtix/blood vessels/nerves, 35%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

What are the functions of gingival fibers?

A
  • Holds marginal gingiva against tooth and prevents its deflection due to masticatory forces
  • Connects marginal gingiva to cementum and to the attached gingiva
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What are the four types of gingival fibers

A
  • Gingivodental
  • Circular
  • Transseptal
  • Alveologingival
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What gingival fiber connects the gingiva to bone?

A

Alveologingival fibers

77
Q

What is the supracrestal attached tissues defined as?

A

The dimension of the soft tissue which is attached to the portion of the tooth coronal to the crest bone

78
Q

The supracrestal attached tissue is how many millimeters in a healthy periodontium?

A

2 mm

79
Q

The apical coronal dimension of the supracrestal attached tissue is measured from the…

A

Coronal aspect of the junctional epithelium to the apical/base of the connective tissue attachment

80
Q

What fluid is secreted from the gingival sulcus?

A

Gingival crevicular fluid

81
Q

What is the composition of the gingival crevicular fluid?

A

Amino acids, plasma proteins, electrolytes, etc.

82
Q

Is there a lot or a little gingival crevicular fluid in a healthy periodontium?

A

A little

83
Q

Is the gingival crevicular fluid increased or decreased in inflamed gingiva?

A

Increased

84
Q

What are six clinical features that sound be identified during a visual exam of the periodontal tissues?

A
  • Color
  • Consistency
  • Contour and shape
  • Surface texture
  • Size
  • Position
85
Q

What color indicates a healthy periodontium?

A

Coral pink

86
Q

What color indicates inflammation in the periodontium?

A

Red or magenta

87
Q

What color indicates pathogenic lesions in the periodontium?

A

Bluish-red

88
Q

What are two examples of endogenous pigmentation?

A
  • Melanin
  • Hemoglobin
89
Q

What are three examples of exogenous pigmentation?

A
  • Amalgam
  • Lead (Burton’s line)
  • Bismuth
90
Q

What is a normal consistency of the periodontium?

A

Firm and resilient

91
Q

What does an edematous consistency of the periodontium indicate?

A

Inflammation, allergic reactions, etc.

92
Q

What does a fibrotic consistency of the periodontium indicate?

A

Smoking

93
Q

What is a normal contour and shape of the periodontium?

A

Knife-edge

94
Q

What are three factors that the contour and shape of the periodontium can depend on?

A
  • Shape of the teeth/alignment in arch
  • Location and size of proximal contact
  • Dimensions of the embrasures
95
Q

Is stippling a sign of healthy or unhealthy gingiva?

A

Healthy

96
Q

What part of the gingiva would be stippled?

A

Attached gingiva, not the marginal gingiva

97
Q

Microscopically, what is stippling produced by?

A

Alternate rounded protuberances and depressions in the gingival surface

98
Q

Is stippling less common on the lingual or facial surfaces?

A

Lingual

99
Q

The size of the periodontium correlates to what?

A

Sum total of the bulk of cellular and intercellular elements and their vascular supply

100
Q

In heathy patients, the gingival margin is position how many millimeters coronal to the CEJ?

A

2 mm

101
Q

What is type 1 recession?

A

Gingival recession with no loss of inter proximal attachment

102
Q

What is type 2 recession?

A

Interproximal attachment loss less than or equal to the buccal site

103
Q

What is type 3 recession?

A

Interproximal attachment loss more than the buccal site

104
Q

What is the alveolar process?

A

Part of the maxilla and mandible that forms and supports the tooth sockets

105
Q

Does the alveolar bone disappear when a tooth is loss?

A

Yes

106
Q

What are the three parts of the alveolar process?

A
  • Cortical bone
  • Alveolar bone proper
  • Cancellous bone
107
Q

What is the technical name for the inner wall of the tooth socket?

A

Alveolar bone proper

108
Q

Does cancellous bone have more or less density? What is inside it?

A
  • Less density
  • Has lots of bone marrow
109
Q

What is the external plate of the alveolar bone?

A

Cortical bone

110
Q

What two things form cortical bone?

A
  • Haversian bone
  • Compacted bone lamellae
111
Q

What type of bone forms the alveolar process?

A

Thin compact bone

112
Q

What does the alveolar process contain to allow neuromuscular bundles link to the periodontal ligament with the cancellous bone?

A

Cribiform plate

113
Q

Is the alveolar bone proper radiolucent or radiopaque?

A

Radiopaque

114
Q

What is in the center of cancellous bone?

A

Trabecular bone

115
Q

What is the basal bone?

A

Portion of the jaw located apically but unrelated to the teeth

116
Q

Most of the facial and lingual portions of the sockets are what type of bone?

A

Compact bone

117
Q

Cancellous bone surrounds the…

A

Lamina dura

118
Q

What are the two main inorganic components of alveolar bone?

A
  • Calcium
  • Phosphate
119
Q

What percentage of alveolar bone is inorganic vs organic?

A
  • Two thirds inorganic
  • One third organic
120
Q

What is the main organic component of alveolar bone?

A

Type 1 collagen fibers

121
Q

Does the number of osteoblasts increase or decrease with aging?

A

Decrease

122
Q

What is the function of osteoblasts?

A

Build new bone

123
Q

What are osteoblasts derived from?

A

Mesenchymal stem cells

124
Q

What is the function of osteoclasts?

A

Eat or reabsorb bone

125
Q

Where are osteoclasts derived from?

A

Monocytes or macrophages

126
Q

Remodeling is the…

A

Bony changes in shape, resistance to forces, repair of wounds, and calcium and phosphate homeostasis

127
Q
A
128
Q

What are howship lacunae?

A

Eroded bone surfaced created by osteoclasts

129
Q

What is an osteoid?

A

Bone matrix that is laid down by osteoblasts

130
Q

How is alveolar bone formed during fetal growth?

A

Intramembranous ossification

131
Q

What are the spaces that enclose osteocytes?

A

Lacunae

132
Q

What processes do osteocytes extend into?

A

Canaliculi

133
Q

Why are canaliculi essential?

A

Bring oxygen and nutrients

134
Q

What is the bundle bone?

A
  • Bone adjacent to the PDL and contains a great number of Sharpy fibers
  • Has thin lamellae
135
Q

The trabecular pattern of cancellous is affected by…

A

Occlusal forces

136
Q

Where is cancellous bone found predominantly in the….

A

Interradicular and interdental spaces

137
Q

What is the periosteum?

A

Tissue that covers the outer surface of bone

138
Q

What is the endosteum?

A

Tissue that lines the internal bone cavities

139
Q

What are the borders of the interdental septum?

A
  • Socket wall cribriform plates
  • Facial and lingual cortical plates
140
Q

If the interdental space is narrow, then the septum may consist only of the…

A

Cribriform plate

141
Q

If the interdental space is wide, then the septum consists of the..

A

Cribriform plate with cancellous bone in the middle

142
Q

The mesiodistal angulation of the crest of the interdental septum usually parallels a line drawn between what structures?

A

The CEJ of approximating teeth

143
Q

The distance between the crest of the bone and the CEJ should be between how many millimeters?

A

1-2 mm

144
Q

What is osseous topography?

A

The bone contour normally conforms to the prominence of the roots, with innervating vertical depressions that taper towards the margin

145
Q

Is the marginal bone intact in a fenestration?

A

Yes

146
Q

Is the marginal bone intact in a dehiscence?

A

No

147
Q

Are fenestrations and dehiscences more common of the facial or lingual bones?

A

Facial

148
Q

Are fenestrations and dehiscences more common on the anterior or posterior?

A

Anterior

149
Q

What are four predisposing factors for fenestrations and dehiscences?

A
  • Prominent root contours
  • Malpositioning
  • Labial protrusion of the root
  • Thin bony plate
150
Q

the number, density, and alignment of cancellous trabeculae is influenced by what?

A

Forces exerted on the tooth

151
Q

What is trauma from occlusion defined as?

A

Forces that exceed the adaptive capacity of the periodontium and produce injury

152
Q

What is the PDL?

A

Complex vascular and highly cellular connective tissue that surrounds the tooth

153
Q

What does the PDL connect?

A

The tooth to the inner wall of the alveolar bone

154
Q

What are the main fibers of the PDL?

A

Principal fibers

155
Q

What are principal fibers mainly composed of

A
  • Type 1 collagen fibers, 80%
  • Type 3 collagen fibers, 20%
156
Q

What are Sharpey’s fibers?

A

Terminal portions of principle fibers that are inserted into bone and cementum

157
Q

Where are the interradicular principle fibers located?

A

In furcations

158
Q

What do transseptal principle fibers connect?

A

One adjacent tooth to another

159
Q

What are the most abundant type of principle fibers?

A

Oblique fibers

160
Q

What is the difference between PDL fibers and gingival fibers?

A

Gingival fibers hold the marginal gingiva against the tooth

161
Q

What is the function of alveolar crest PDL fibers?

A

Prevent the extrusion of the tooth and resist lateral tooth movements

162
Q

Where do horizontal PDL fibers extend from?

A

Extend at right angles from the long axis of the tooth from the cementum to the alveolar bone

163
Q

Where do oblique fibers extend from?

A

Cementum in a coronal direction obliquely to the bone

164
Q

What PDL fibers bear the brunt of vertical masticatory stress?

A

Oblique fibers

165
Q

What fibers are not present in incompletely formed roots?

A

Apical fibers

166
Q

What are the three components of ground substance?

A
  • Glycossaminoglycans (GAGs)
  • Glycoproteins
  • Water
167
Q

What are two significant PDL functions?

A
  • Transmission of occlusal forces to bone
  • Resistance to the impact of occlusal forces/shock absorption
168
Q

Is cementum vascular or avascular?

A

Avascular

169
Q

Is cementum neural or aneural?

A

Aneural

170
Q

What is the definition of cementum?

A

Calcified mesenchymal tissue that forms the outer covering of the anatomical root

171
Q

What color is cementum?

A

Yellow, darker and less shiny

172
Q

Is cementum harder or softer than dentin?

A

Cementum is softer than dentin

173
Q

What are the three organic components of cementum?

A
  • Extrinsic collagen fibers/Sharpey’s fibers
  • Intrinsic collagen fibers
  • Interfibrillar ground substance
174
Q

What are the two inorganic components of cementum?

A
  • Hydrozyapatite
  • Floride
175
Q

What type of cementum does not contain cells?

A

Acellular cementum

176
Q

What type of cementum contain cells?

A

Cellular cementum, contains cementocytes

177
Q

When does acellular cementum form?

A

First to form, before the tooth reaches the occlusal plane

178
Q

Acellular cementum is mainly composed of…

A

Sharpey’s fibers

179
Q

What type of cementum is formed after the tooth reaches the occlusal plane?

A

Cellular cementum

180
Q

What does acellular cementum cover?

A

Cervical half of root

181
Q

What does cellular cementum cover?

A

Apical third/half and furcation areas

182
Q

Is cellular cementum more or less calcified?

A

Less calcified

183
Q

Where do cementocytes reside at?

A

Lacunae

184
Q

How do cemntocytes communicate with each other?

A

Through a system of anastomosing canaliculi

185
Q

What is the cementodentinal junction?

A

Terminal apical area of the cementum where it joins the internal root canal dentin

186
Q

What three ways can blood vessels reach the PDL space?

A
  • Apical vessels
  • Transalveolar vessels
  • Gingival vessels
187
Q

The deep cervical lymph nodes drain what areas?

A
  • Palatal gingiva
  • Tissue around 3rd molars
188
Q

The submental lymph nodes drain tissues around what areas?

A

Mandibular incisors

189
Q

The submandibular lymph nodes drain tissues around what areas?

A

All other areas besides the palatal gingiva, tissue near 3rd molars, and mandibular incisors

190
Q

What nerve innervates the periodontium?

A

Trigeminal nerve

PERI 326 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions