Gender assessment through three-dimensional analysis of maxillary sinuses by means of cone beam computed tomography

OBJECTIVE

The availability of a low dose radiation technology such as Cone Beam Computed Tomography (CBCT) in dental practice has increased the number of scans available for forensic purposes. Moreover, specific software allows for three-dimensional (3D) characterization of the maxillary sinuses. This study was performed to determine whether sinus maxillary volumes can be useful to identify gender after validating the use of the Dolphin software as a tool for volumetric estimation of maxillary sinus volumes.

PATIENTS AND METHODS

The validation was performed by four different operators measuring the volume of six phantoms, where the real volume was already known. The maxillary sinus volumes of 52 patients (26 males and 26 females) mean age 24.3 were calculated and compared between genders and sagittal skeletal class subdivision. The measurements for patients and phantoms were based on CBCT scans (ILUMA™) processed by Dolphin 3D software.

RESULTS

No statistical difference was observed between the real volume and the volume measurements performed by the operators. No statistical difference was found in patient's maxillary sinus volumes between gender.

CONCLUSIONS

Based on our results, it is not possible to support the use of maxillary sinuses to discern sexual difference in corpse identification.

Third Class Resolver: a retrospective analysis

AIM

To evaluate the use of Third Class Resolver (TCR), a new fixed and functional orthopaedic appliance for the treatment of skeletal Class III malocclusion in adolescents and young adults.

MATERIALS AND METHODS

Study design: Retrospective analysis. Twenty subjects, 10 females and 10 males, affected by Class III malocclusion were treated with a new fixed orthopaedic appliance: the Third Class Resolver (TCR). The mean age was 7 years at the beginning of treatment and 9 years at the end of treatment. The mean treatment time was 6 months. Digital cephalometric superimpositions on lateral radiographs taken at the start and end of treatment were assessed. The cephalometric values were statistically analysed.

RESULTS

Cephalometric analysis of changes during treatment shows a statistically significant increase of ANB angle (mean 1°) (P = 0.045); increase of Witts Index (mean 3.5 mm) (P = 0.003); decrease of Maxillo-Mandibular angle (MM) (mean -2.3°) (P = 0.047); increase of Upper incisor-Maxilla Plane angle (angle mean 10.5°) (P = 0.02); increase of the distance between Upper Incisor and A-Pg line (mean 2.4 mm) (P = 0.021); increase of the mandibular branch length (mean 4.8 mm) (P = 0.004).

CONCLUSION

TCR can be used fully for treatment of Class III malocclusions.

Second Class Resolver: a retrospective analysis

AIM

To evaluate the use of Second Class Resolver (SCR), a new fixed orthopaedic appliance, for the treatment of skeletal Class II malocclusion in growing subjects.

MATERIALS AND METHODS

Design Retrospective analysis. Forty subjects were treated with Second Class Resolver (SCR). The mean age was 8 years at the beginning of treatment and 10 years at the end of treatment. Digital cephalometric superimpositions on lateral radiographs taken at start and end of treatment were assessed. The cephalometric values were statistically analysed.

RESULTS

Cephalometric analysis of changes during treatment shows reduction of ANB angle (mean 2°); reduction of Witts Index (mean 3 mm); reduction of Maxillo-Mandibular angle (MM) (mean 1°); reduction of SNA (angle mean 3°); reduction of gonial angle (mean 1.8°); increase of the mandibular branch length (mean 5 mm); increase of mandibular body (mean 2.9°).

CONCLUSION

The Second Class Resolver can be beneficially used for the treatment of Class II malocclusion.

Histomorphologic alterations of human enamel after repeated applications of a bleaching agent

The objective of the study was to analyse the histomorphology of enamel after repeated applications of a professional bleaching regimen. Enamel specimens were obtained from buccal surfaces of 20 extracted human incisors. Two specimens were obtained for each tooth. Half of each tooth was maintained in distilled water and served as control; the other part was treated with a 38 percent hydrogen peroxide professional bleaching agent. The treated specimens were divided in four groups: in group 1, the professional bleaching protocol suggested by the manufacturer was applied once; in group 2, the same protocol was repeated twice; in group 3, three times; in group 4, four times. Between bleaching applications and before SEM evaluation, enamel specimens were maintained in artificial saliva for 1 week. Enamel specimens for each group were submitted to a qualitative scanning electron microscopy (SEM) analysis (200X, 500X, 1000X, 3000X), comparing the treated specimens with the related control enamel. Results of the SEM analysis showed no relevant alteration on the enamel surfaces, when the bleaching protocol was applied once or twice. However, significant changes of enamel surface morphology were SEM observed in groups 3 and 4, suggesting a predominance of depressions when bleaching procedure was repeated three or four times. From the results of this in vitro study, it is possible to state that bleaching procedures should not be carried out indiscriminately. SEM analysis showed important alterations of the prismatic structure of the enamel when the bleaching protocol was applied three and four times.

Modification of condyle anatomy following a monolateral bite rise: a histological study in rat

The aim of this study is to evaluate the histologic modifications of rat articular capsules, after compression and strain. Fifty adults Sprague Dawley rats were used in this study. The rats were divided into 3 groups: a dysfunction group, treatment group and a Control group. In the rats in the first two groups an occlusion hump, made of composite and less than 0.5 mm high, was applied to the upper right molar. The rats were anesthetized with an intraperitoneal injection of benzodiazepine (0.5-1 mg for 100 g. of body weight). The composite used consisted of a hollow, plastic cylinder 0.5 mm high, spread over the whole occlusal surface of the right upper molar. The dysfunction group therapy wore the occlusion hump for a week, at the end of which the animals in this group were killed and their temporomandibular joint removed. In the treatment group a second occlusion hump was applied to the left upper molar, in order to obtain a distraction of the previously compressed temporomandibular joint. The rats of the second group wore the second occlusion hump for one week. The rats were then killed with an intraperitoneal injection of Tanax, and the block sections, containing the temporo-mandibolar joint, were retrieved with a diamond disk, and surrounding tissues were washed in saline solution and immediately fixed in 4 percent formalin for 4 days. In the control group, no treatment was applied. In the first group, bone resorption was observed in the left temporomandibular joint; no osteoclast were, however, present. No other tissue alterations were present. Newly formed bone undergoing remodelling was intensely stained with acid fuchsin. In the second and third groups, no bone remodelling areas were observed. In conclusion, the compression of the temporomandibular joint determined a remodelling of the bone structure of the condyle.

Role of the friction free distalize appliance (2FDA)PAT in the molar distalization: photoelastic analysis and alkaline-phosphatase (ALP) activity on first molar and bicuspid

Maxillary molar distalization is an increasingly popular option for the resolution of Class II malocclusions. This study describes the effects of one particular molar distalizing appliance, the Friction Free Distalize Appliance (2FDA), in a sample of 20 consecutively treated and growing patients to verify the osteoblastic activity in the compression and traction sites of both the molars and the bicuspids when used as the anchorage teeth. The 2FDA appliances were constructed utilizing a Nickel Titanium open coil spring of 200 gr force in order to distalize the maxillary first molar. The reaction force was controlled utilizing the principle of low/free friction. The results show that the resin around the root of the bicuspid did not discolour at all, which indicates an absence of a force load. On the other hand, on the molar, the resin around the root of the molar became discoloured due to the fact that an orthodontic force was involved with the tooth. To better understand whether the quantity of force that reached the tooth was able to produce osteoblastic recruitment in the sites of tension of the molar and the bicuspid, we quantified an enzyme, the alkaline phosphatase (ALP), present. This measurement allowed us to verify a regular increase of the ALP on the site of molar traction. We also elaborated a mathematical model to evaluate the quantity of force of reaction that produces the device on the bicuspid. Such force results as being 8.34 grams which equals half the pressure of the capillaries of the parodontal ligament (18 grams). The 2FDA appliance compares favourably with other intra-oral distalization devices for the resolution of patients with Class II malocclusions, and is the only distalizing appliance that does not determine osteoclastic/osteoblastic recruitment on the anchorage tooth.

Enamel surface after debracketing of orthodontic brackets bonded with flowable orthodontic composite. A comparison with a traditional orthodontic composite resin

AIM

Flowable composites showed acceptable shear bond strength for bonding orthodontic brackets, but it still lacks evidence if the routine clean-up of this type of composites from enamel surface after debracketing is susceptible of more difficult procedure, due to their fluidity, and, consequently, more enamel lesions, compared with traditional orthodontic composites. Thus, this in vitro study investigated this point.

METHODS

Stainless steel brackets were bonded to 60 extracted human premolars using: 1) a new flowable composite (Denfil Flow) (group I; N=20); 2) a traditional flowable composite (Dyract Flow) (group II; N:20); 3) Transbond XT adhesive (group III; N=20). Twenty untreated teeth were the control group. After a routine debonding procedure, the adhesive remnant index (ARI) was calculated in each tooth. After the following clean-up procedure, enamel cracks (measurements about their frequency, their position in the tooth crown and their direction) were evaluated using fiber-optic transillumination. Finally, enamel surfaces were analyzed with scanning electron microscope to quantify enamel lesions

RESULTS

A significantly higher frequency of enamel cracks, (from 65% to 80%), mostly in the cervical third of tooth crown (from 65% to 80%) and vertical (from 75% to 80%), were observed in the three study groups, compared with the control group (P<0.05), without difference among the three study groups. The index of enamel lesions was significantly higher in the three study groups, compared with control group (P<0.05), without significant differences among the three study groups.

CONCLUSION

Flowable composites seem to show no relevant differences in terms of enamel lesions and cracks compared with traditional composites.

Functional infrared imaging in the diagnosis of the myofascial pain

Functional infrared imaging has been used to study 17 patients, affected by myofascial pain, and 19 healthy subjects during maximal voluntary clenching (MCV). Aim of the study was to attempt to discriminate patients from healthy subjects through the analysis of the skin temperature distribution and its change during the clenching. The prestress and the post-stress temperatures were evaluated bilaterally for several regions of interest. We calculated differences in temperature between sides (DeltaTs) at each time (pre and post), and between times (DeltaTt) for each side (left and right). Subsequently, we compared DeltaTs and DeltaTt between the healthy and myofascial pain groups. DeltaTs was significantly higher in sufferers compared to healthy people (p<0.05) for both types of evaluation (by side and by time). DeltaTs was significantly different for masseter and sternocleidomastoid, whereas DeltaTt was higher in almost all sites (masseter, sternocleidomastoid, cervical and upper trapezius). Healthy subjects, undergoing MVC, showed the lowest DeltaT value variability, suggesting that temperature remained constant despite the induced physical exercise. Functional infrared imaging seems to distinguish healthy subjects from the patients suffering myofascial pain in almost all the investigated sites.

Effects of anterior cruciate ligament (ACL) injury on postural control and muscle activity of head, neck and trunk muscles

The aim of the study was to evaluate the effects that an anterior cruciate ligament injury of the knee has on postural control and activity of neck, head and trunk muscles to investigate the existence of connections between the masticatory system and body posture. Surface electromyographic activity of the muscles at mandibular rest position, and during maximal voluntary clenching and posturometric and stabilometric measurements of 25 adult patients having pathology on the left knee were compared with a control non-pathological group. At rest, the patients showed a higher muscular activity of anterior temporalis, masseter, sternocleidomastoid and lower trapezius, compared with the control subjects (P < 0.05). At maximal voluntary clenching, the patients showed a lower muscular activity of the right anterior temporalis and masseter and a higher muscular activity of the lower trapezius, compared with the control subjects. For the stabilometric measurements, all the subjects showed a significant reduction in the postural centre of pressure path length during the test with eyes open and cotton rolls, compared with the test with eyes closed and mandibular rest position (P < 0.05). In addition, the patients showed a significant displacement of the postural centre of pressure in a forward direction (P < 0.05) and into the right side (P < 0.05), compared with the control subjects. Anterior cruciate ligament injury appears to be associated to a change in the activity of head, neck and trunk muscles and to a change in the position of the postural centre of pressure. Cotton rolls seem to improve the stability of the subject.

Surface electromyographic response of the neck muscles to maximal voluntary clenching of the teeth

The purpose of this study was to evaluate the activity of digastric, sternocleidomastoid, upper trapezius, lower trapezius and cervical muscles in response to maximum voluntary clenching (MVC) of the teeth. Twenty healthy subjects aged 24-31 years were divided into two groups of 10: a resting group and a clenching group. The resting group simply maintained the mandible at rest with teeth apart for two 1-min periods, whereas the clenching group underwent an initial resting period followed after 1-min by a clenching period during which they were required to perform MVC. The electromyography (EMG) responses of each muscle were recorded during all periods, and means and standard deviations of the root mean square EMG were calculated. Within-group and between-group comparisons of EMG activity were made using, respectively, the Sign two-tailed test for two related samples and the Kolmogorov-Smirnov two-tailed test for two independent samples (significance level 0.05). Data indicated a significant increase of EMG activity of the anterior neck muscles (digastric and sternocleidomastoid) during MVC as compared with EMG recorded during resting periods. If confirmed by further research, our findings suggesting an involvement of anterior neck muscles during isometric contraction of the jaw elevator muscles may have clinical implications.

[Activation of mandibular growth with the Fräenkel II device: assessment of effects on the vertical plane]

BACKGROUND

The aim of the study was to evaluate if a function Fräenkel II Regulator therapy can increase the vertical dimension of the cranio-facial district. Enlow's cephalometric analysis was used to measure the proportion between cranial and facial components without references to the population average.

METHODS

Twenty patients were selected, with dental class II, skeletal class II and mandibular hypoplasy and normal facial biotype. The patients were treated for 24 months only with Fräenkel II and the appliances was activated 2 mm every 6 months. The follow-up was of the 2 years and cephalometric tracings were made at the beginning and after therapy.

RESULTS

The results showed an increase of vertical dimension and the change of occlusal plane inclination after the therapy. This inclination compensates basal dysarmonies and increases the vertical dimension.

CONCLUSIONS

The results are not statistically significant, but they underline the importance of Fräenkel's regulator function to change negative tendency growth.

Site-specific subgingival colonization by Actinobacillus actinomycetemcomitans in orthodontic patients

A high prevalence of Actinobacillus actinomycetemcomitans (Aa) in subgingival plaque in patients for orthodontia already has been observed. The present study had the following aims: 1) to ascertain a direct relationship between the orthodontic appliance placement and the subgingival colonization by Aa, and 2) to determine whether the Aa growth specifically occurred on teeth with braces attached or whether the presence of orthodontic appliances could also cause the isolation of Aa in teeth free from therapeutic appliances. Twenty-four young systemically and periodontally healthy subjects with malaligned and crowded teeth in the anterior sextants of both dental arches participated in this study. After 1 session of ultrasonic scaling with oral hygiene instructions during the first experimental session, the mesiobuccal sites of the first molars and the distobuccal sites of the lateral incisors in both dental arches in each participant were subjected to clinical and microbiologic examination for the recovery of Aa. Clinical examination consisted of recording the presence of plaque and the examination of gingival bleeding on probing and probing depth. Microbiologic sampling was obtained with the insertion of 3 sterile paper points at the deepest part of each gingival sulcus. Altogether, 192 periodontal sites were examined. After the examinations, the patients received fixed orthodontic appliances in only 1 dental arch (test sites) and the other one was left free from appliances (control sites). Clinical examination and microbiologic sampling were repeated in the same experimental test and control sites after 4, 8, and 12 weeks. At the 12-week session, the orthodontic appliance was removed from the test arch, and, 4 weeks later, a further clinical and microbiologic examination was performed. The results showed that, during the period with orthodontic appliances, the presence of plaque scores and the gingival bleeding on probing scores were increased significantly and that Aa, initially absent from all but 1 subject, was isolated in 19 and 20 subjects after 4 and 8 weeks, respectively. Furthermore, no gingival sites from the control teeth (free from Aa colonization at baseline) showed positive results for the sought-after bacterium throughout the entire length of the study. It was concluded that the placement of orthodontic appliances promotes the subgingival growth of Aa; this specific microbial change is specifically restricted to subgingival plaque from orthodontic appliance-bearing teeth. The presence of orthodontic bands and brackets therefore cannot affect the microbiologic condition of the whole mouth.

[Legal medicine and dentistry]

With reference to cases of American dentists sued for "malpractice" during the 80s, the authors summarise the causes why, initially, the American lawyers found it difficult to plead on behalf of their clients. Therefore, the authors suggest a number of measures in order to reduce the probability of being sued by patients. In particular, they focus attention on:--the duty to treat patients, with reference to experimentation on humans within the context of scientific research and citing the Declaration of Helsinki;--informed consent, with particular emphasis on the need to inform the patient regarding all aspects of treatment, including any risks or presumed complications that might arise during and after treatment;--professional liability, drawing a distinction between moral responsibility (regulated by the Code of Professional Practice) and legal liability (involving the legal field). Lastly, the authors underline the need to perfect and increase the awareness of the "management" risk of a dental practice, drawing special attention to the need to keep precise records on patients receiving treatment: radiographical and photographical examination, remote and recent medical history, the current state of teeth and gums, the presence of clicks and/or crepitus on ATM, cephalea, spontaneous and/or provoked pain involving masticatory and cervical muscles, obtaining the informed consent of the patient.