Current advances in orthodontic pain.

Orthodontic pain is an inflammatory pain that is initiated by orthodontic force-induced vascular occlusion followed by a cascade of inflammatory responses, including vascular changes, the recruitment of inflammatory and immune cells, and the release of neurogenic and pro-inflammatory mediators. Ultimately, endogenous analgesic mechanisms check the inflammatory response and the sensation of pain subsides. The orthodontic pain signal, once received by periodontal sensory endings, reaches the sensory cortex for pain perception through three-order neurons: the trigeminal neuron at the trigeminal ganglia, the trigeminal nucleus caudalis at the medulla oblongata and the ventroposterior nucleus at the thalamus. Many brain areas participate in the emotion, cognition and memory of orthodontic pain, including the insular cortex, amygdala, hippocampus, locus coeruleus and hypothalamus. A built-in analgesic neural pathway-periaqueductal grey and dorsal raphe-has an important role in alleviating orthodontic pain. Currently, several treatment modalities have been applied for the relief of orthodontic pain, including pharmacological, mechanical and behavioural approaches and low-level laser therapy. The effectiveness of nonsteroidal anti-inflammatory drugs for pain relief has been validated, but its effects on tooth movement are controversial. However, more studies are needed to verify the effectiveness of other modalities. Furthermore, gene therapy is a novel, viable and promising modality for alleviating orthodontic pain in the future.

Management of an impacted maxillary central incisor with dilacerated root.

Dilaceration is a comparatively uncommon dental deformity generally characterized by an angulation between crown and root, and consequently causing non-eruption of the tooth. Dilaceration generally occurs following trauma to the apices of deciduous dentition, which lies close to the permanent tooth buds. As a result, surgical extraction used to be the first choice when making the treatment plan for a case with severely dilacerated teeth. This case report presents the orthodontic alignment of a permanent maxillary right central incisor in an 8-year-old boy who had an impacted inverted maxillary central incisor, with distoangular root dilaceration through the crown. Following surgical exposure with the closed-eruption technique and appropriate orthodontic traction, the tooth was successfully aligned into the dental arch and the root was radiologically shown to be straightened and relatively well developed. The impacted dilacerated incisor diagnosed in the early mixed dentition should be treated with the aid of orthodontic traction.

Validity assessment and determination of the cutoff value for the Index of Complexity, Outcome and Need among 12-13 year-olds in Southern Chinese.

To validate the use of the Index of Complexity, Outcome and Need (ICON) in assessing orthodontic treatment need among 12-13 year-olds in southern China, we determined the threshold value of ICON based on Chinese orthodontists' judgments. The samples consisted of 335 students in grade 7 from 16 randomly selected middle schools in Chengdu, China. Three associate professors provided ICON scores for each participant and the results were compared with the gold standard judgments from 25 experts on treatment needs. Based on the gold standard, 195 casts belonged to the treatment category, while the rest 140 belonged to the no-treatment category. With the international cutoff point of 43, the sensitivity and specificity of the ICON score were 0.29 and 0.98.The best compromise between sensitivity and specificity in Chengdu, compared with the gold standard, was found at a cutoff point of 29, and the sensitivity and specificity were 0.88 and 0.83. When used to evaluate the treatment need of 12-13 year-olds in southern China, the international ICON cutoff value did not correspond well with Chinese orthodontists' judgments; a lower cutoff value of 29 offered a greater sensitivity and specificity with respect to expert orthodontists' perception of treatment need.

[Expression of ligand-gated cation channels P2X3 receptor in rat pulp during experimental tooth movement].

OBJECTIVE: To investigate ligand-gated cation channels P2X3 receptors changes in rat pulp during experimental tooth movement (ETM), and preliminarily find their possible effect during ETM. METHODS: 54 male SD rats (200-250 g) were selected and randomly divided into blank group (5 rats), control group (14 rats) and experimental group (35 rats). The left maxillary first molar was selected as observation object, the pulp tissue biopsies was taken at different time points to carry out immunohistochemical study. RESULTS: Predominant up regulation of P2X3 receptors immunoactivity was found in pulp from 1/6 d to 7 d after experimental tooth movement. It started to significantly increase at 1/6 d, peaked at 3 d, and then decreased continuously until 7 d as compared with the beginning. CONCLUSION: P2X3 receptors have a rhythm change in rat pulp as a result of ETM, speculated that P2X3 receptors is closely related to the tooth movement injury, but the mechanism of action need further researches.

[Cleidocranial dysplasia: a case report].

A case of cleidocranial dysplasia (CCD) was reported and relevant literatures were reviewed. The diagnosis and treatment of this case were discussed.

[Multiple retained deciduous teeth: a case report].

Retained deciduous teeth are defined as the succedaneous permanent teeth have erupted while the primary teeth were retained, or the permanent teeth unerupted while the primary teeth remained in the permanent dentition. One case of multiple retained deciduous teeth was reported.

[Analysis of clinical features and mutation associated with oligodontia].

OBJECTIVE: To investigate the mutation characteristics of paired box homeotic gene 9 (PAX9) and muscle segment homeobox gene 1 (MSX1) of patients with congenital oligodontia. METHODS: Clinical manifestations were recorded by taking complete oral examinations in patients with congenital nonsyndromic oligodontia and some of his normal family members. Pedigree information was confirmed by extended interviews and a pedigree was constructed. Inheritance mode and clinical features were analyzed. Assessment of crown width compared to normal value of crown width in Chinese people was based on the registrations and measurements of study cast. Comparison of craniofacial form, malocclusion types and characteristics were conducted via cephalometric analysis by taking lateral cephalometric radiographics. Venous blood samples were collected and DNA was extracted from leukocytes. DNA sequencing and mutation analysis were analyzed in exon 1, 2, 3, 4 of PAX9 and exon 1, 2 of MSX1 coding region by polymerase chain reaction (PCR). RESULTS: The teeth shape abnormality of the patient was noticed by a measured smaller crown width compared to normal values of crown width in Chinese people. The result of cephalometric analysis indicated no obvious inherited tendency in the proband in terms of facial osseo type and jaw bone pattern. One mutation was found in the proband and his mother in exon 3 of PAX9, the missense mutation G718C causing a conservative change A240P was present. Mutation was not found in MSX1. CONCLUSION: These findings suggest that the missense mutation G718C in exon 3 of PAX9 is likely the cause of oligodontia.

[Facial profile preference among four panels].

OBJECTIVE: To determine the facial profile preference among four groups of persons and the influence of vertical proportion and skeletal anteroposterior relation on facial profile esthetics. METHODS: One hundred and twenty persons, comprising of adult patients, adolescents' parents, laypersons and orthodontists, participated this study. The subjects were asked to rate 27 silhouettes which represented the male facial profiles with various vertical proportion and anteroposterior relation. RESULTS: The silhouette II-1s scored highest while the one III-4s scored lowest (P < 0.05). The silhouette I-normal was rated highest by orthodontists while the ones II-normal and II-1s were rated highest by other three groups. The silhouette III-4s was scored lowest by all groups (P < 0.05). CONCLUSIONS: Vertical discrepancy had influence on Chinese male facial profile esthetics and the influence was related to the degree of vertical malformation and skeletal anteroposterior relation. Class III skeletal pattern had the most negative influence on male profile esthetics. The four panels had different esthetic standard. The preference of facial profile esthetics was related to orthodontic education background rather than gender or age.

[Orthodontic treatment on primary dentition of a child with mandible fracture: a case report].

Fixed orthodontic treatment is rarely used on primary dentition. In this paper, a primary dentition child with mandible fracture was treated with orthodontic treatment appliance. The occlusal function was improved and the fracture was recoveried after treatment.

[Psychological impact on the adolescent patients at the beginning of the fixed orthodontic treatment].

OBJECTIVE: To assess whether there is a short negative psychological influence on adolescent patients at the beginning of the fixed orthodontic treatment. METHODS: 150 patients (average 14.8 years old) were selected. All the patients accepted the fixed appliance treatment. They completed a questionnaire regarding anxiety and depression at the first day when they came to the hospital (T1) and 7 days after fixed appliance insertion (T2). 129 effective questionnaires were received. The scales of anxiety and depression of subjects were assessed according to the questionnaires. RESULTS: Comparing the scales of questionnaires before treatment (T1) and 7 days after placement of fixed appliance (T2), there was a significant increase in anxiety and depression scales in female patients, extraction cases and patients who were unwilling to see an orthodontist. CONCLUSION: There is a certain extent of negative psychological influence on adolescent patients during fixed orthodontic treatment. At the first week after the placement of fixed appliance, three kinds of subjects, female patients, extraction cases and patients who were unwilling to see an orthodontist would suffer from anxiety and depression in emotional reflection.

[Differential regulation of P2X3 mRNA expression in the rat trigeminal ganglion after experimental tooth movement].

OBJECTIVE: To investigate the regulation of P2X3 mRNA expression in the trigeminal ganglion sensory neurons after the nociceptive stimulation by orthodontic tooth movement force. METHODS: Male Sprague-Dawley rats weighing 200-250 g were used. The mimic tooth movement appliance was used in the rats of the experiment group. The rats were sacrificed after 4 h, 12 h, 1 d, 2 d, 3 d, 5 d and 7 d after experiment. The expression of P2X3 mRNA was detected by in situ hybridization with an oligonucleotide probe. RESULTS: After force was given to the teeth of rats, the number of P2X3 mRNA positive neurons increased on the first day and reached the peak on the third day; then, the level of P2X3 mRNA expression began to decrease, and after seven days, it returned to the level of the control group. CONCLUSION: The results suggest that the P2X3 mRNA expression is transiently upregulated and anterogradely transported in trigeminal primary sensory neurons after orthodontic tooth movement and that P2X3 receptor may play a role in the pathomechanism of nociception in primary sensory neurons during orthodontic treatment.

[Differential regulation of P2X3 protein expression in the rat trigeminal ganglion after experimental tooth movement].

OBJECTIVE: To investigate the regulation of P2X3 protein expression in the trigeminal ganglion sensory neurons after the nociceptive stimulation by orthodontic tooth movement force. METHODS: Male Sprague-Dawley rats weighing 200-250 g were used. The mimic tooth movement appliance was used in experimental group rats. The animals were sacrificed after 4 h, 1 d, 2 d, 3 d, 5 d, 7 d and 14 d. The semi-quality of P2X3 protein was measured by Western blot. The expression place and strength of P2X3 was detected by in situ hybridization with an oligonucleotide probe in the same time. RESULTS: A major specific protein of 4.5 x 10(4) was found by Western blot in trigeminal ganglion of rats. The expression strength of P2X3 receptor increased after given force to the teeth of rats from 1 day of experiment, 3 day group rats showed peak change. 14 day group had returned to control values. The level change of P2X3 mRNA expression showed the same result. CONCLUSION: The results suggest that the P2X3 receptor expression is transiently upregulated and anterogradely transported in trigeminal primary sensory neurons after orthodontic tooth movement and that P2X3 receptor may play role in the pathomechanism of nociceptive in primary sensory neurons during orthodontic clinic treatment.