Disparities in Timing of Alveolar Bone Grafting and Dental Reconstruction in Patients With Clefts.

This study sought to identify disparities in the timing of alveolar bone grafting (ABG) surgery and the replacement strategy for missing maxillary lateral incisors for patients with clefts.A retrospective record review identified patients who underwent ABG. Multivariable regression analyzed the independent contribution of each variable.This institutional study was performed at the University of California, San Francisco.Patients who presented under age 12 and underwent secondary ABG between 2012 and 2020 (n = 160).The age at secondary ABG and the recommended dental replacement treatment for each patient, either dental implantation or canine substitution.The average age at ABG was 10.8 ± 2.1 years, 106 (66.3%) patients were not White, and 80 (50.0%) had private insurance. Independent predictors of older age at ABG included an income below $ 50 000 as estimated from ZIP code (ß = 15.0 months, 95% CI, 5.7-24.3, P = .002) and identifying as a race other than White (ß = 10.1 months, 95% CI, 2.1-18.0, P = .01). After ABG, patients were more likely to undergo dental implantation over canine substitution if they were female (odds ratio [OR] = 4.3, 95% CI, 1.3-17.1, P = .02) or had private insurance (OR = 12.5, 95% CI, 2.2-143.2, P = .01).Patients who were low-income or not White experienced delays in ABG, whereas dental implantation was more likely to be recommended for patients with private insurance. Understanding the sources of disparities in dental reconstruction of cleft deformities may reveal opportunities to improve equity.

Eye-blink conditioning is associated with changes in synaptic ultrastructure in the rabbit interpositus nuclei.

Eye-blink conditioning involves the pairing of a conditioned stimulus (usually a tone) to an unconditioned stimulus (air puff), and it is well established that an intact cerebellum and interpositus nucleus, in particular, are required for this form of classical conditioning. Changes in synaptic number or structure have long been proposed as a mechanism that may underlie learning and memory, but localizing these changes has been difficult. Thus, the current experiment took advantage of the large amount of research conducted on the neural circuitry that supports eye-blink conditioning by examining synaptic changes in the rabbit interpositus nucleus. Synaptic quantifications included total number of synapses per neuron, numbers of excitatory versus inhibitory synapses, synaptic curvature, synaptic perforations, and the maximum length of the synapses. No overall changes in synaptic number, shape, or perforations were observed. There was, however, a significant increase in the length of excitatory synapses in the conditioned animals. This increase in synaptic length was particularly evident in the concave-shaped synapses. These results, together with previous findings, begin to describe a sequence of synaptic change in the interpositus nuclei following eye-blink conditioning that would appear to begin with structural change and end with an increase in synaptic number.

Unique changes in synaptic morphology following tetanization under pharmacological blockade.

Long-term potentiation (LTP) in the hippocampus has been associated with changes in synaptic morphology. Whether these changes are LTP-dependent or simply a result of electrophysiological stimulation has not yet been fully determined. This study involved an examination of synaptic morphology in the rat dentate gyrus 24 h after electrophysiological stimulation sufficient to induce LTP. In one group, ketamine, a competitive NMDA antagonist, was injected prior to stimulation to block the formation of LTP. Synaptic morphological quantification included estimating the total number of synapses per neuron, determining synaptic curvature and the presence of synaptic perforations, and measuring the maximal PSD profile length of the synapses. The results indicated that most of the changes observed following the induction of LTP (increases in the proportion of concave-shaped synapses, increases in perforated concave synapses, and a decrease in the length of nonperforated concave synapses) are not observed under ketamine blockade, suggesting that they are LTP-specific and not simply the result of tetanic stimulation. Ketamine was associated, however, with several novel structural changes including a decrease in the length of the perforations in the concave perforated synapses, a reduction in the number of convex perforated synapses, and a nonlayer-specific increase in synaptic length compared to controls. Based on previous research, this combination of morphological characteristics is potentially less efficacious, which suggests that synapses that are tetanized but not potentiated, due to pharmacological blockade, appear to undergo opposing, compensatory, or homeostatic changes. These results support the suggestion that synaptic morphology changes are both stimulation- and area-specific, are highly complex, and depend on the specific local physiology.