Evaluation of the palatal split pattern in surgically rapid maxillary expansion—comparison of two techniques

Purpose

Surgically assisted rapid maxillary expansion is performed to correct transverse deficiencies of the maxilla, and it is indicated in specific clinical situations. The literature presents different opinions in several aspects, mainly regarding the effect of disjunction of the pterygoid plates. The aim of this study was to evaluate the pattern of maxillary expansion obtained with two surgical techniques, with and without disjunction of the pterygoid plates.

Methods

Twenty patients treated with surgically assisted rapid maxillary expansion for correction of transversal discrepancies were included in this retrospective study and divided into two groups: (G1) patients operated without disjunction of pterygoid plates and (G2) patients treated with release of the pterygoid plates.

Results

There were seven male and 13 female patients, and the mean age was 29.9 years. Cone beam computed tomography images obtained after final activation of the expansion device were evaluated and complete disjunction of the midpalatal suture (type I) was present in 75 % of the patients whereas incomplete disjunction of the midpalatal suture (type II) was observed in 25 %. Chi-square test showed no statistically significant difference between groups (p = 0.606).

Conclusion

No difference was found in relation to the maxillary disjunction pattern irrespective of the treatment given to pterygoid plates.

     

Stress analysis of tooth and supporting tissue using the finite element method —Effect of properties of periodontal membrane—

We investigated changes in natural teeth under loading and the correspondence of simulated models to these results using the finite element method. Four kinds of models were analyzed according to loading conditions at the periodontal membrane. Two models for linear analysis and two models for nonlinear analysis were established. The influences of these 4 models on stress distribution were compared. The following results were obtained. 1) The differences Young’s modulus at the Periodontal membranes greatly affected the structure analysis; 2) a loading-deviation curve approximating actual values was observed under the loading condition of NL-2 at the periodontal membrane; and 3) comparison of stress distribution at the alveolar bone in linear and nonlinear analysis models indicated that the neutral axis appears only in the linear analysis models, suggesting that it is important to define and establish the periodontal membrane as the nonlinear elastic body.

     

The effect of vertical bracket positioning on torque and the resultant stress in the periodontal ligament—a finite element study

Background

The ideal built-in tip and torque values of the straight wire appliance reduce the need for wire bending and hence reduce chair time. The vertical position of the bracket on the tooth surface can alter the torque exerted on the tooth. This is a result of the altered surface curvature observed at each vertical position. To further clarify the role of vertical bracket positioning on the applied torque and the resultant stresses in the periodontal ligament (PDL), we designed a mandibular first premolar using finite element modeling.

Methods

Cone beam computed tomography of 52 patients (83 lower first premolars) was selected to be included in the study. Curvature was measured for points along the labial surface with increasing distances (0.5 mm increments) from the cusp tip by calculating the angle between tangents drawn from these points and the axis joining the cusp tip and the root apex. The mean values for each distance were calculated, and a finite element model was designed incorporating these mean values. The resultant stress and hydrostatic pressure in the PDL were calculated using finite element analysis.

Results

The labial surface of the mandibular first premolar demonstrated a 26.39° change from 2.5 to 6 mm from the cusp tip. The maximum Von-Mises stress and hydrostatic pressure in the PDL were observed at the root apex for all of the bracket positions, and these values demonstrated, respectively, a change of up to 0.059 and 0.186 MPa between two successive points.

Conclusions

It can be concluded that the variation in the vertical position of the bracket can have an important effect on the torque and subsequently on the stresses and pressures in the PDL.     

Surgically assisted rapid maxillary expansion with bone-borne versus tooth-borne distraction appliances—a systematic review

The objective was to test the hypothesis of no difference in skeletal and dental arch expansion and relapse after surgically assisted rapid maxillary expansion with a bone-borne compared with a tooth-borne appliance. The PubMed, Embase (Ovid), Cochrane Library, and Google Scholar databases were searched in combination with a hand-search of relevant journals up until December 2017. No language restriction was applied. Two short-term randomized controlled trials with a low risk of bias fulfilled the inclusion criteria. No meta-analysis could be performed due to considerable heterogeneity. There were no statistically significant differences in the skeletal and dental arch expansion and relapse. Dental arch expansion was significantly greater than skeletal expansion with both treatment modalities. However, dissimilar evaluation methods, different outcome measures, unknown vertical level of force application with the bone-borne devices, and various methodological confounding factors posed serious restrictions to reviewing the literature in a quantitative systematic manner. Hence, conclusions drawn from the results of this systematic review should be interpreted with caution. Further well-designed long-term randomized clinical trials including a standardized protocol and three-dimensional analysis of the level of force application and morphological outcome are therefore needed before one treatment modality can be considered superior to the other.     

Does the timing and method of rapid maxillary expansion have an effect on the changes in nasal dimensions?

The aim of this study was to assess the effects of rapid maxillary expansion (RME) and surgical assisted rapid maxillary expansion (SARME) on nasopharyngeal area. The study group consisted of 30 subjects in the permanent dentition who had both maxillary constriction and a posterior cross-bite. The patients were divided into two groups, RME and SARME. The subjects in the RME group consisted of 15 patients (eight girls, seven boys) whose average age was 12.1 +/- 1.1 years. The SARME group also consisted of 15 patients (eight boys, seven girls) whose mean age was 18.4 +/- 1.4 years. An acrylic bonded RME appliance was used in both groups. Surgery was performed using lateral cortical osteotomies in the SARME group. The nasopharyngeal and respiratory area was determined using a digital planimeter on lateral cephalometric radiographs taken before and after RME. Nasal cavity width was evaluated on postero-anterior radiographs. Nasal dimension was measured using planimeter measurements of the respiratory and nasopharyngeal areas before and after treatment. The data obtained were analyzed using SPSS. Comparisons within the groups were carried out with paired t-tests and comparisons between the groups were with a Student's t-test. In both groups, the respiratory area and the ratio of the respiratory area to nasopharyngeal (RA/NA) area increased following RME. There were no statistically significant differences between the groups. Nasal cavity width and maxillary width also increased, but the difference between the groups was not significant. Following RME, various differences in both the maxilla and surrounding bones occurred and nasal width increased with a decrease in nasal airway resistance. At the end of treatment there were increases in the width of the nasal floor near the midpalatal suture and nasal cavity. As the maxillary structures separated, the outer walls of the nasal cavity moved laterally resulting in an increase in internasal volume. Nasal resistance decreased and respiratory area increased in patients treated with RME.     

Effect of radiation dose on the prevalence of apical periodontitis—a dosimetric analysis

Objectives

The objective of this study is to analyse the effect of the radiation dose of oral radiotherapy for cancer on the presence of apical periodontitis in patients without dental pre-screening or specific preventive measures.

Materials and methods

All selected patients had been diagnosed with cancer in the head and neck region and presented in the dental clinic post radiotherapy with side effects (mainly radiation caries). The panoramic radiographs of these patients were examined for several parameters, including tooth decay and apical periodontitis. The total radiation dose per tooth was determined.

Results

A total of 36 patient files were included, which accounted for 628 teeth to be scored. Tooth decay was present in 88.2% of teeth. Radiographic signs of apical periodontitis were found in 9.1% of the teeth. Teeth with apical periodontitis had significantly more caries present. The radiation dose was significantly higher for teeth with apical periodontitis (37.2 vs. 24.9?Gy). Binary logistic regression found the radiation dose to be the only explanatory variable in the presence of apical periodontitis.

Conclusions

This study found that in zones with higher radiation dose, inflammation of the jawbone due to bacterial infection of the root canal is more likely to develop. This is probably due to bone changes post radiotherapy.

Clinical relevance

An increase of this prevalance of apical periodontitis in irradiated bone found in this study needs to be taken into account in the dental evaluation before the start of radiotherapy.     

The short-term treatment effects on the microbiota at the dorsum of the tongue in intra-oral halitosis patients—a randomized clinical trial

Objectives

This study aims to assess the effects of rinsing with zinc- and chlorhexidine-containing mouth rinse with or without adjunct tongue scraping on volatile sulfur compounds (VSCs) in breath air, and the microbiota at the dorsum of the tongue.

Material and methods

A randomized single-masked controlled clinical trial with a cross-over study design over 14 days including 21 subjects was performed. Bacterial samples from the dorsum of the tongue were assayed by checkerboard DNA–DNA hybridization.

Results

No halitosis (identified by VSC assessments) at day 14 was identified in 12/21 subjects with active rinse alone, in 10/21with adjunct use of tongue scraper, in 1/21 for negative control rinse alone, and in 3/21 in the control and tongue scraping sequence. At day 14, significantly lower counts were identified only in the active rinse sequence (p?<?0.001) for 15/78 species including, Fusobacterium sp., Porphyromonas gingivalis, Pseudomonas aeruginosa, Staphylococcus aureus, and Tannerella forsythia. A decrease in bacteria from baseline to day 14 was found in successfully treated subjects for 9/74 species including: P. gingivalis, Prevotella melaninogenica, S. aureus, and Treponema denticola. Baseline VSC scores were correlated with several bacterial species. The use of a tongue scraper combined with active rinse did not change the levels of VSC compared to rinsing alone.

Conclusions

VSC scores were not associated with bacterial counts in samples taken from the dorsum of the tongue. The active rinse alone containing zinc and chlorhexidine had effects on intra-oral halitosis and reduced bacterial counts of species associated with malodor. Tongue scraping provided no beneficial effects on the microbiota studied.

Clinical relevance

Periodontally healthy subjects with intra-oral halitosis benefit from daily rinsing with zinc- and chlorhexidine-containing mouth rinse.     

The effects of ULF–TENS stimulation on gnathology: the state of the art

Aims: The aim of this study was to evaluate the state of the art in the current literature regarding the effect of ultra low frequency–transcutaneous electrical nerve stimulation (ULF–TENS) on patients with temporomandibular disorders (TMD).

Methodology: The authors reviewed the literature through a thorough manual and electronic research on PubMed database (using the Medical Subject Headings thesaurus) and subsequent analysis of all the found papers regarding the effect of TENS on TMD patients. No randomized controlled trials on the investigated topic were found. Only eight papers regarding controlled clinical trials (CCT) were selected according to the search strategy selection criteria.

Results: According to the available literature and the authors’ experience, ULF–TENS seems to be a valid support in the management of TMD patients, but also a ‘provocative’ tool, so its application should always be monitored by electromyographic and electrognathographic analysis (before and after TENS). Conclusions: Further clinical studies (mainly randomized controlled trials) on ULF–TENS application in neuromuscular gnathology are needed.     

The role of diabetes mellitus on the formation of severe odontogenic abscesses—a retrospective study

Objectives

To analyze the correlation of diabetes mellitus and hyperglycemia with severe odontogenic abscesses.

Materials and methods

Records of all patients in the Department of Oral and Maxillofacial Surgery of the Medical Center of the Johannes Gutenberg-University who underwent inpatient treatment for severe odontogenic abscesses between 2010 and 2016 were evaluated retrospectively regarding diabetes anamnesis, maximum and fasting blood sugar count, and duration until discharge. In order to compare the numbers to a general maxillofacial group, all patients who received inpatient treatment in 2013 for any diagnosis other than an abscess of the head and neck region were analyzed as well, and the numbers were correlated.

Results

In total, 977 abscess patients were found in the analyzed period. 7.0% of the patients had a known diagnosis of diabetes mellitus type II and 0.6% of type I. Correlation with the general group showed that abscesses were significantly more likely in diabetics as well as patients with abnormal maximum and fasting blood sugar counts. These patients also needed significantly longer inpatient treatment.

Conclusions

Diabetics and patients with abnormal glucose tolerance show significantly higher numbers of severe odontogenic abscesses and might therefore benefit from earlier escalation of antibiotic medication.

Clinical relevance

Severe odontogenic abscesses are one of the most frequent diagnoses in maxillofacial practice. Adjusting the therapeutic approach for diabetics or patients with abnormal blood sugar counts might help to prevent the development of abscesses.

     

Does surgically assisted rapid maxillary expansion associated with pterygomaxillary disjunction result in changes in mandibular position? A PROSPERO-compliant systematic review of the literature

PurposeThis study aimed to assess the effect of surgically assisted rapid maxillary expansion (SARME) associated with pterygomaxillary disjunction (PD) on mandibular positioning.Materials and methodsA two-phase systematic review registered with the PROSPERO database was performed. Search strategies were developed for specific databases (PubMed, Scopus, Web of Science, COCHRANE, LILACS, and DOSS), including the gray literature (Open Gray, Google Scholar, and ProQuest). The methodological and evidential quality of the included studies were assessed.ResultsAmong 680 studies, four were selected for inclusion. In general, a low risk of bias was observed. The studies included a total of 142 adults, and used imaging to perform linear measurements (preoperatively and postoperatively). The main outcomes were maxillomandibular transverse index (difference between effective mandibular width — distance between the left and right antagonist points — and maxillary width), sagittal (forward and backward) and vertical (impaction and extrusion) changes, dental show, chin projection, and altered mandibular position.ConclusionAlthough the study demonstrated some mandibular position changes after SARME associated with PD, there is insufficient current evidence to support this result because of the potential study limitations related to the number of investigations chosen for inclusion. Further research is required to validate this finding.     

Inhibitory effects of a collagen–mineral complex on deterioration of bone mass and bone quality in ovariectomized mice

Objectives

To characterize the osteoporosis-preventive effects of a novel material consisting of a complex of type 1 collagen and hydroxyapatite (CCH) in osteoporosis model mice.

Methods

Ten-week-old ovariectomized (OVX) ICR mice were used. The five study groups comprised a sham group, OVX control group, calcium carbonate (CaCO₃) group, vitamin K₂ [menaquinone 7 (MK7)] group, and CHH group (n = 10 each). The CaCO₃ and CHH groups were fed a special diet containing 2 % of the respective substance, whereas the MK7 group received a special diet containing 0.5 % MK7. After maintenance of the animals under these conditions for 8 weeks, their femurs were removed and blood samples were collected. The bone mineral densities (BMDs) of the distal femoral epiphysis were analyzed by peripheral quantitative computed tomography. Three-dimensional images were rendered with micro-focus computed tomography, and the trabecular structures were determined.

Results

The significantly lower BMDs in the epiphyseal and diaphyseal regions of the OVX control group femurs compared with the sham group femurs were clear osteoporotic signs. The trabecular structure analyses revealed 12 parameters that were significantly lower in the OVX control group compared with the sham group. No distinct changes in the BMD or trabecular structure were observed in the CaCO₃ group. Significant improvements in the BMD in the MK7 group were limited to three parameters, whereas 11 trabecular structure parameters were significantly improved. The CHH group showed significant improvements in seven BMD parameters and seven trabecular structure parameters.

Conclusions

CHH improves trabecular structure and BMD in a well-balanced manner.     

The effect of DLC-coating deposition method on the reliability and mechanical properties of abutment’s screws

Objective

To characterize the mechanical properties of different coating methods of DLC (diamond-like carbon) onto dental implant abutment screws, and their effect on the probability of survival (reliability).

Indirect miniscrew anchorage: biomechanical loading of the dental anchorage during mandibular molar protraction—an FEM analysis

Aims

While there are many studies in the literature addressing direct miniscrew anchorage, the biomechanical effects of indirect miniscrew anchorage remain unknown. The aim of the present study was to biomechanically analyze the load on the anchor teeth during mandibular molar protraction using different types of anchorage.

Materials and methods

Four finite element method (FEM) models of the right mandible were created using the morphological CT data of a 21-year-old male. All models were morphologically identical, but they differed in anchorage type (dental anchorage, direct miniscrew anchorage, indirect miniscrew anchorage with one anchor tooth, indirect miniscrew anchorage with two anchor teeth). To analyze the load on the dental anchorage during mandibular molar protraction, we measured the induced effective strain (µstrain) at specific control points on the alveolar bone.

Results

With indirect miniscrew anchorage, we observed that the effective strain at an average of 7.21 μstrain (one anchor tooth) or 6.57 μstrain (two anchor teeth) was almost as high as in pure dental anchorage where no miniscrew was used (mean 8.38 µstrain). In contrast, we noted significantly lower strain values in conjunction with direct miniscrew anchorage. We observed highly significant differences between direct and indirect simulated miniscrew anchorage (p=0.008).

Conclusion

Our FEM results reveal relatively high loads on the dental anchorage when using indirect miniscrew anchorage. This may carry an increased risk of anchorage loss during mandibular molar protraction; however, further studies are necessary to confirm this.     

The single mandibular implant study – Short-term effects of the loading protocol on Oral Health-related Quality of Life

Purpose

A single implant can be placed to retain an overdenture in the edentulous mandible. This study aimed at the development of Oral Health-related Quality of Life comparing immediate and delayed implant loading, i.e., loading after 3 months of submerged healing.

Microstructure analysis of dental castings used in fixed dental prostheses—a simple method for quality control

The aim of this study was to evaluate the microstructural quality of noble alloy castings from commercial dental laboratories using the wiping–etching method as a simple method for quality control. In total, 240 castings from two noble alloys (AuAgCuPt and AuPtZn) were taken from a day's production of five different dental laboratories. The casting quality was evaluated by determining the grain size and by assessing the number and size of shrinkage cavities after acidic etching of the alloy surfaces. The AuAgCuPt alloy castings showed an acceptable quality in the microstructural analysis. The results of AuPtZn castings, however, were not satisfactory because 50.8% of the samples showed a remarkably poorer quality compared to the specifications made by the manufacturer. The proportion of the employed reclaimed alloy had no influence on the casting quality when AuAgCuPt alloy was used, but was influential when casting restorations with AuPtZn alloy. When determining the quantity and size of shrinkage cavities, none of the evaluated castings was of such a poor quality that a replacement of the castings had to be considered. The differences in grain size and quantity of shrinkage cavities were reflecting the individual laboratory process rather than the admixture of new/reclaimed alloy. The presented analysis can be used as a simple method for quality control of dental castings.     

The effect of a long-acting local anaesthetic agent (Marcaine®) on the masticatory muscle in rats

Marcaine®, a long-acting local anaesthetic was administered subcutaneously over the rat's superficial masseter muscle. Rapid muscle fibre destruction with infiltration of mononuclear and polymorphonuclear leukocytes and degeneration of muscle fibers are the notable morphological changes following treatment with Marcaine®. However, this degeneration was rapidly replaced by a regeneration process. Sequential injections of Marcaine produced even more serious muscle damage. However, successive injections of the drug did not prevent the regeneration process.