Modeling and remodeling of human extraction sockets.
BACKGROUND
The available studies on extraction wound repair in humans are affected by significant limitations and have failed to evaluate tissue alterations occurring in all compartments of the hard tissue defect.


OBJECTIVE
To monitor during a 6-month period the healing of human extraction sockets and include a semi-quantitative analysis of tissues and cell populations involved in various stages of the processes of modeling/remodeling.


METHODS
Twenty-seven biopsies, representative of the early (2-4 weeks, n=10), intermediate (6-8 weeks, n=6), and late phase (12-24 weeks, n=11) of healing, were collected and analysed.


RESULTS
Granulation tissue that was present in comparatively large amounts in the early healing phase of socket healing, was in the interval between the early and intermediate observation phase replaced with provisional matrix and woven bone. The density of vascular structures and macrophages slowly decreased from 2 to 4 weeks over time. The presence of osteoblasts peaked at 6-8 weeks and remained almost stable thereafter; a small number of osteoclasts were present in a few specimens at each observation interval.


CONCLUSIONS
The present findings demonstrated that great variability exists in man with respect to hard tissue formation within extraction sockets. Thus, whereas a provisional connective tissue consistently forms within the first weeks of healing, the interval during which mineralized bone is laid down is much less predictable.
Trombelli
Leonardo
L
Research Centre for the Study of Periodontal Diseases, University of Ferrara, Ferrara, Italy. leonardo.trombelli@unife.it
Farina
Roberto
R
Marzola
Andrea
A
Bozzi
Leopoldo
L
Liljenberg
Birgitta
B
Lindhe
Jan
J
D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D001706:Biopsy; D001857:Bone Matrix / Q000166:cytology; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D001861:Bone Regeneration / Q000502:physiology*; D016723:Bone Remodeling / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006097:Granulation Tissue / Q000166:cytology; D006801:Humans; D008297:Male; D008334:Mandible; D008437:Maxilla; D008875:Middle Aged; D015675:Osteocalcin / Q000378:metabolism; D010519:Periodontium / Q000033:anatomy & histology* / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D053245:RANK Ligand / Q000378:metabolism; D013997:Time Factors; D014081:Tooth Extraction; D020390:Tooth Socket / Q000033:anatomy & histology* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014945:Wound Healing / Q000502:physiology*; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D015675:Osteocalcin; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D053245:RANK Ligand; D016212:Transforming Growth Factor beta; C525819:BMP7 protein, human; C067980:CD68 antigen, human; D000097382:CD68 Molecule