Effect of CBX7 deficiency on the socket healing after tooth extractions

CBX7 is shown to down-regulate the expression of osteopontin (OPN) that is associated with osteoblast function. Here, we studied the role of CBX7 in the wound healing of tooth extraction socket in which osteoblast activity is critical via comparison between CBX7-knockout (CBX7^-/-) mice and their wild-type (WT) counterparts of 6 weeks old with maxillary first molar extracted. Mice were euthanized at 7, 14, and 21 days after extractions, and alveolar sockets were assessed by semi-quantitative histomorphometry for hard tissue healing, including new bone fill (Masson's trichrome staining), osteoblast activity (OPN/osterix, Osx), osteoclast activity (tartrate-resistant acid phosphatase, TRAP), and for soft tissue healing, including blood vessels (alpha smooth muscle actin, α-SMA). Also, the bone microarchitecture was evaluated by micro-CT. In radiological analysis, CBX7^-/- mice increased bone mass significantly more than WT mice did. Consistently, both the amount of new bone fill and OPN/Osx-immunopositive cells in the extraction sockets were significantly increased in CBX7^-/- mice at each time point with respect to their WT siblings, while osteoclast number exhibited a trend of more increase in CBX7^-/- mice at all time points as well. In agreement with enhanced bone formation during socket healing, significantly elevated α-SMA-immunopositive area was noted in CBX7^-/- mice in contrast to WT mice. Taken together, these data suggest that CBX7 deficiency has a positive effect on tooth extraction socket healing.

Soft tissue healing in alveolar socket preservation technique: histologic evaluations

After tooth extraction, 14 alveolar sockets were grafted with porous bovine bone mineral particles and covered with non-cross-linked collagen membrane (test group), and 14 alveolar sockets were left uncovered. At 5 and 12 weeks, microvascular density (MVD), collagen content, and amount of lymphocytes (Lym) T and B were analyzed in soft tissue. At 5 weeks, MVD was significantly lower and Lym T was significantly higher in tests than in controls (P < .05). At 12 weeks no differences were found. Placement of resorbable membrane seems to induce an initial and transient modification of the normal wound healing process of the soft tissue.

An extraction socket classification developed using analysis of bone type and blood supply to the buccal bone in monkeys

Bone modeling and remodeling following tooth extraction has been studied extensively. The reason for bone loss during the remodeling process is multifactorial, and the primary reason for this loss is still yet to be determined. The aim of this study was to examine the type of bone and the blood supply to the buccal bone in monkeys. Six maxillary arches from six monkeys were used. The arches were divided into three sections: right posterior, anterior from canine to canine, and left posterior. Blocks were decalcified and prepared for histologic processing and examination. Modified Masson trichrome and retic staining were used. Histologic sectioning demonstrated that the blood supply to the buccal bone came from the inner (socket) side of the alveolus, the periodontal ligament, the adjacent interdental bone, and the supraperiosteal vessels emanating from the covering gingiva or mucosa. Histologic examination showed that the buccal bone was composed of bundle and cortical bone. The thickness of the buccal bone was not uniform coronoapically, and the thinnest area of buccal bone was the coronal portion.

Effects of an intravenous infusion of Ringer's solution on eruption rates of incisor teeth in anesthetized rats

OBJECTIVE

The vasculature within the socket is reportedly involved in determining the position of continuously erupting teeth. Thus, loss of body fluid in anesthetized rats, which would affect the vascular physiology, should influence tooth movement. We investigated the effects of an infusion of Ringer's solution on the systemic arterial blood pressure, regional blood flow at the base of the incisor, and axial tooth movement in anesthetized rats to determine the cause of tooth displacement.

MATERIAL AND METHODS

In the experimental group, the animals received intravenous infusions of Ringer's solution at 27 microl/min for 13 h. In the control group, the animals did not receive the infusion.

RESULTS

The infusion of Ringer's solution suppressed an increase of the mean arterial blood pressure from 86 to 80 mmHg and a decrease of the regional blood flow from 170 to 217 mV, and increased the eruption rate from 267 to 361 microm/13 h during the experimental period. There was a positive correlation between the eruption rate and regional blood flow, and a negative correlation between the blood pressure and regional blood flow.

CONCLUSIONS

These results suggest that an infusion of Ringer's solution can cause an increase in the regional blood flow, resulting in increased fluid volume, elevated intra-socket pressure, and increased eruptive movement. It is possible that the regional vascular volume and/or pressure within the socket play an important role in determining the position of the incisor.

Ultrastructural changes in postcapillary-sized venule morphology in aged mouse periodontal ligament

The aim of this study was to compare the postcapillary-sized venule (PCV) morphology of four young ALCA mice (35 days) and four colony-related aged mice (365 days) using the transmission electron microscope (TEM). Right and left mandibular first molar mesial roots with associated periodontal ligament (PDL) and bony socket, were used for TEM assessment. Five PCV profiles were selected at each 160 microm interval, from the alveolar crest to the tooth apex. PCV profile dimensions were measured on standardised micrographs magnified x2900. Age affects were tested using multiple regression analysis. The number of PCV profiles in the tooth third of the PDL was higher in aged mice (p < 0.01) and comprised predominantly apericytic vessels (p < 0.001). The number of PCV profiles increased significantly (p < 0.001) in aged mice in the PDL middle circumferential third halfway down the molar root. Age had no significant affect on PCV diameter. Aged PDL permeability studies are needed to investigate whether the changes in aged PCV profile number are associated with functional modification of the PDL microvasculature.

Dental extraction wound management: medicating postextraction sockets

The rather impressive percentage of extraction sites undergoing clot loss and deranged healing results in significant morbidity for the patient and frequent visits to the surgeon to effect relief of discomfort, most often by the use of anodyne dressings. The amount of work lost by patients needing such palliative treatment, and loss of productive time for the surgeon, translate into an unknown, but potentially large, economic loss to society. This would mandate that economical methods of ensuring normal extraction socket healing with minimal morbidity be developed. The most useful socket medicaments to prevent socket healing derangements would include broad-spectrum antibiotics, specifically clindamycin and tetracycline. Not discussed in this article, but possibly germane to the subject of clot stabilization and healing, is consideration of resorbable substances such as gelatin sponge, polylactic acid, and methylcellulose as clot-stabilizing socket implants. The record of such substances in preventing AO is mixed, but the combinations of these inexpensive materials with topical socket medicaments may yield a decreased tendency for clot lysis and greater mechanical strength to the bulk blood clot, as has been demonstrated with difficult mandibular third molar impactions in one study involving polylactic acid, tetracycline, and hydrocortisone.