bone y types qaulity

7/31/2019 Bone y Types Qaulity

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Bone types (Histological)

Depending on age, developmental stage, localization and function bone consists of:

Woven bone Lamellar bone Bundle bone


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Can be found in the vicinity of blood vessels during

Woven bone

Is formed rapidly (approximately 30 to 50 microm per day)

Prenatal development

Bone growth

Bone healing

Bone types (Histology)


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Woven bone

It is of great importance for initial healing-in of endosseous implants.


It is richer in cells and shows irregular arrangement of newly developed collagen fibers

It seems to have a low mineral content and a lower mechanical strength


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Has a markedly higher mineral content than its woven bone

Lamellar bone


It is the principal component of the compact and cancellous regions in the adult skeleton

It is less rich in cells

It is formed at a slower rate (less than 1 microm per day) than woven bone tissue.

Blood vessels traverse within bone tissue in a system (Haversian and Volkmanns canals)


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Bundle bone


Can be found in the zones of attachment of tendons, ligaments, or joint capsules

It is mineralized bone penetrated by collagen fibers (parallel bundles of collagen fibrils)

Serving as zone of attachment for the periodontal ligament to alveolar bone and cementum.

It can also be found around endosseous implants that are enveloped by connective tissue


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In keeping with this definition compromised bone would predict a poor outcome without

performance accompanying measures

Bone Quality

The term bone quality in general describes the current condition of the bone and helps to

predict the outcome of treatment


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For implant clinicians, bone quality is a determinant of the success of osseointegration

and the retention of implants in the alveolar bone

Internists who see patients with osteoporosis associate compromised bone with the riskof vertebral or other fractures.

For orthopedists, compromised bone is associated with a poor regenerative potential afterinjuries, fractures, or osteotomies.

Bone Quality


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Bone Quality

Lekholm and Zarb were the first to study the structural quality of bone systematically with

implant dentistry in mind

Lekholm U,Zarb tissue integ Prostheses:Osseointegration in Clinical Dentistry. Chicago: Quintess 1985:199-209

They distinguished four types of structural bone morphology in edentulous jaws, taking into

account both cortical and cancellous elements


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It distinguishes four types of bone quality

The classification described by Lekholm and Zarb is widely used for evaluating structural

factors clinically

Bone Quality



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Type 4: A thin cortical layer surrounding loosely structured cancellous bone

Type I: Largely homogeneous cortical bone

Type 2: A thick cortical layer surrounding dense cancellous bone

Type 3: A thin cortical layer surrounding dense cancellous bone

Bone Quality


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Bone Quality

Lekholm and Zarb showed that

Implants in type I through type 3 bone perform well clinically

For implants placed in type 4 bone, by contrast, long-term success rates have been

comparatively lower (50% to 94%).

The higher failure rates are attributable to the poor primary stability of implants in type 4

bone, which does not ensure successful osseointegration


Martinez H, Davarpanah M, Missika RCelletti R, Lazzara R. Optimal implant stabilization in low density bone. Clin Oral Implants Res 2001; 12:423-432.


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The relative amounts of cortical and trabecular bone determine bone quality

The trabecular structure itself gives some clues to bone quality

Has a higher turnover rate than cortical bone

Bone Quality

Watzek Implants in Qualitatively Compromised Bone Quintess 2004 1-9

Trabecular bone is filled with bone marrow

It is the source of osteoblasts and osteoclasts


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Many studies have shown differences in trabecular bone volume like

Males generally have a larger trabecular volume than Females

In the molar region, the trabecular bone volume is lower than in the incisor region

In the mandible, the trabecular density is more pronounced than in the maxilla

Ulm C, Kneissel M, Schedle A, et al. Characteristic features of trabecular bone in edentulous maxillae, Clin Oral Implants Res 1999; 10:459-467.

Ulm CW Kneissel M, Hahn M, et al Characteristics of the cancellous bone of edentulous mandibles. Clin Oral Implants Res 1997;8:125-130.

Bone Quality


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Bone Resorption After Tooth Loss

Atrophy of alveolar bone

after tooth extraction

The alveolar ridge is affected by dramati c, extensive and irreversible resorptive process

that have a lasting influence on the planned implant host site

Atrophy of the alveolar process cannot be compared with the conventional age-related

atrophy of the remaining skeleton

Alveolar ridge atrophy is a chronic, progressive and irreversible disease(Atwood 1971; Atwood and Coy 1971)


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The resorptive process is highly influenced by the fact that:

In edentulous mandible and maxilla the load is not transferred to the entire bone but only to

the bone surface



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12.0 Cm2 in the mandible

Normally the mean surface of the periodontium is approx. 45 Cm2per arch

In edentulous patients the denture-bearing area is approx.

23.0 Cm2 in the maxilla




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Vertical resorption

Examining a large group of patients, Atwood and

Coy (1971) found that the total loss of vertical bone volume

Averages 0.5 mm per year in complete-denture wearers

The vertical dimensions of the mandible is reduced by 0.4 mm

The vertical dimensions of maxilla is reduced by 0.1 mm



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In single tooth gaps excessive resorption and severe vertical bone reduction are prevented

by the adjacent teeth

Vertical resorption


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Horizontal resorption


caused by the pressure exerted by the lips, cheeks, and tongue (Netwig 1983)

Horizontal resorption generally starts at the thinner alveolar wall (Heidelbach, 1982)

The new alveolar margin is located more lingually during the first months after tooth loss


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The mandibular Alveolar ridge moves buccally particularly in the posterior region

(centrifugal, eccentric)

The maxillary alveolar ridge moves palatally (centripetal, concentric).

This leads to absolute expansion of the mandibular arch compared to the maxillary arch


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In single tooth gaps the adjacent teeth dont prevent horizontal ridge resorption ,

small , knife-edged are often developed




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