Influence of base designs on the manufacturing accuracy of vat-polymerized diagnostic casts using two different technologies.

STATEMENT OF PROBLEM: Diagnostic casts can incorporate different base designs and be manufactured using different vat-polymerization technologies. However, the influence of the interrelation between the base design and the 3D printing technology on the casts' final accuracy remains unclear. PURPOSE: The purpose of this in vitro study was to assess the influence of different base designs of 3D printed casts on the accuracy of 2 vat-polymerization technologies. MATERIAL AND METHODS: A digital maxillary cast was obtained and used to generate 3 different base designs: solid (S group), honeycombed (HC group), and hollow (H group). The HC and H groups were subdivided based on the wall thickness of the cast design, resulting in 2 subgroups with thicknesses of 1 mm (HC1 and H1) and 2 mm (HC2 and H2) (N=100, n=10). Eleven reference cubes were added to each specimen for subsequent measurements. Specimens were manufactured by using 2 vat-polymerization 3D printers: Nextdent 5100 (ND group) and Sonic Mini 4K (SM4K group) and a resin material suitable for both 3D printers (Nextdent Model 2.0). A coordinate measuring machine quantified the linear and 3-dimensional discrepancies between the digital cast and each reference specimen. Trueness was defined as the average absolute dimensional discrepancy between the virtual cast and the specimens produced through additive manufacturing (AM), while precision was delineated as the standard deviation in dimensional discrepancies between the digital cast and the AM specimens. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U pairwise comparison tests (α=.05). RESULTS: For the NextDent group the trueness ranged from 21.83 µm to 28.35 µm, and the precision ranged from 17.82 µm to 37.70 µm. For the Phrozen group, the trueness ranged from 45.15 µm to 64.51 µm, and the precision ranged from 33.51 µm to 48.92 µm. The Kruskal-Wallis test showed significant differences on the x-, y-, and z-axes and in the 3D discrepancy (all P<.001). On the x-axis, the Mann-Whitney U test showed significant differences for the Phrozen group between the H-2 and H-1 groups (P=.001), H-2 and S groups (P<.001), and HC-2 and S groups (P=.012). On the y-axis, significant differences were found in the Phrozen group between the H-2 and H-1 groups (P=.001), the H-2 and S, H-1 and HC-1, and HC-1 and S groups (P<.001), the H-1 and HC-2 groups (P=.007), and the HC-2 and S groups (P=.009). The NextDent group exhibited significant differences, particularly among the HC-1 and H-2 groups (P=.004), H-1 (P=.020), and HC-2 (P=.001) groups; and on the z-axis significant differences were found in the Phrozen group between the H-2 and H-1 and S groups and the HC-2 group and H-1 and S groups (both P<.001). In the NextDent group, significant differences were found between the H-2 and HC-2 (P=.047) and HC-1 (P=.028) groups. For the 3D discrepancy analysis, significant differences were found in the Phrozen group between the H-2 and H-1 and S groups (P<.001), the H-1 and HC-2 groups (P=.001), the S and HC-1 and HC-2 groups (P<.001), and the H-1 and HC-1 groups (P=.002). In the NextDent group, significant differences were observed between the H-2 and HC-1 groups (P=.012). CONCLUSIONS: The accuracy of digital casts depends on the manufacturing trinomial and base design of the casts. The honeycomb and hollow based designs provided the highest accuracy in the NextDent and Phrozen groups respectively for the material polymer tested. All specimens fell in the clinically acceptable range.

OralImmunoAnalyser: a software tool for immunohistochemical assessment of oral leukoplakia using image segmentation and classification models.

Oral cancer ranks sixteenth amongst types of cancer by number of deaths. Many oral cancers are developed from potentially malignant disorders such as oral leukoplakia, whose most frequent predictor is the presence of epithelial dysplasia. Immunohistochemical staining using cell proliferation biomarkers such as ki67 is a complementary technique to improve the diagnosis and prognosis of oral leukoplakia. The cell counting of these images was traditionally done manually, which is time-consuming and not very reproducible due to intra- and inter-observer variability. The software presently available is not suitable for this task. This article presents the OralImmunoAnalyser software (registered by the University of Santiago de Compostela-USC), which combines automatic image processing with a friendly graphical user interface that allows investigators to oversee and easily correct the automatically recognized cells before quantification. OralImmunoAnalyser is able to count the number of cells in three staining levels and each epithelial layer. Operating in the daily work of the Odontology Faculty, it registered a sensitivity of 64.4% and specificity of 93% for automatic cell detection, with an accuracy of 79.8% for cell classification. Although expert supervision is needed before quantification, OIA reduces the expert analysis time by 56.5% compared to manual counting, avoiding mistakes because the user can check the cells counted. Hence, the SUS questionnaire reported a mean score of 80.9, which means that the system was perceived from good to excellent. OralImmunoAnalyser is accurate, trustworthy, and easy to use in daily practice in biomedical labs. The software, for Windows and Linux, with the images used in this study, can be downloaded from https://citius.usc.es/transferencia/software/oralimmunoanalyser for research purposes upon acceptance.

Accuracy assessment (trueness and precision) of a confocal based intraoral scanner under twelve different ambient lighting conditions.

OBJECTIVES: The ambient lighting condition has been identified as an important factor that influences the accuracy of intraoral scanners (IOSs). The purpose of this study was to evaluate the influence of 12 different ambient lighting conditions on the accuracy of a confocal based IOS (PrimeScan). MATERIALS AND METHODS: A typodont was digitized using a laboratory scanner (L2i) to obtain a reference standard tessellation language (STLr) file. A restorative dentist recorded the scans using an IOS (PrimeScan) under 12 different ambient lighting conditions where the luminosity was measured using a light meter (LX1330B Light Meter). Twelve groups were created, namely 0-, 500-, 1000-, 2000-, 3000-, 4000-, 5000-, 6000-, 7000-, 8000-, 9000-, and 10 000 lux groups. Ten STL files were recorded per group. The STLr file was used as a reference with which to compare the distortion of the 120 STL files obtained using a software program (Meshlab). The normality Shapiro-Wilk test indicated that the distributions were not normal. Therefore, the nonparametric Kruskal-Wallis and pairwise multicomparison tests were used to analyze the data (α = 0.05). RESULTS: The group with the 1000 lux lighting condition obtained the smallest median ±interquartile range (IQR) with scanning distortion values of 69.5 ± 97.4 µm, followed by the 8000 lux group with a median ±IQR of 166.5 ± 318.1 µm. The 0 lx group presented the highest distortion values with a mean ±IQR of 355.5 ± 488.0 µm (p < 0.05). CONCLUSIONS: Ambient lighting conditions influenced the accuracy of the IOS tested. The highest accuracy values were obtained with 1000 lux. The lowest scanning accuracy was obtained with 0 lux.

Importance of the vaporization margin during CO2 laser treatment of oral leukoplakia: A survival study.

OBJECTIVES: The main purpose of this study was to assess the response of oral leukoplakia to CO2 laser vaporization treatment, as well as determining possible factors that may affect recurrence of lesions. MATERIALS AND METHODS: A retrospective study was conducted, in which the medical records of patients who had been clinically and histologically diagnosed with oral leukoplakia and treated with CO2 laser between 1996 and 2019 at the Oral Medicine Teaching Unit of the Faculty of Dentistry of the University of Santiago de Compostela were reviewed. RESULTS: Fifty-eight patients were included: 36 female and 22 male subjects, with a mean age of 63.7 years old (SD ±13.1). The average follow-up time was 57.5 months (SD ±57.9). A relapse rate of 52.6% was determined. Of all the studied variables, the margin was the only one for which a statistically significant association with recurrence of lesions was demonstrated (p < 0.05). CONCLUSION: The vaporization of lesions using CO2 laser with a safety margin of at least 3 mm from the clinical limits of OL is a key factor in preventing recurrence.

Efficacy of different sentinel lymph node biopsy protocols in oral squamous cell carcinoma: Systematic review and meta-analysis.

The sentinel node biopsy (SNB) is highly protocolized in other cancers, however, this is not the case for oral squamous cell carcinoma patients, hence our objective was to evaluate the different protocols published. A specific study protocol was designed and subsequently registered on PROSPERO (Ref. CRD42021279217). Twenty-three articles were included in the meta-analysis. The grouped sensitivity of the SNB was 82% (95% CI: 0.74-0.88), and the grouped specificity was 100% (95% CI: 0.99-1.00). The use of other radiotracers other than pre-operative lopamidol showed higher values of sensitivity of 82.80% (95% CI: 76.90%-87.50%; p < 0.001). The use of the blue dye stain showed higher sensitivity values of 85.60% (95% CI: 71.90%-93.20%), compared to sensitivity values of 77.50% when it was not used (95% CI: 69.10%-84.20%) (p < 0.001). Diagnostic rates are variable and they were significantly better when 99mTc was used in all its variations and accompanied by the blue dye staining.

Efficacy of photobiomodulation in reducing pain and improving the quality of life in patients with idiopathic burning mouth syndrome. A systematic review and meta-analysis.

Burning mouth syndrome is a chronic condition, which is characterised by a burning sensation or pain in the mucosa of the oral cavity. Treatment options include antidepressants, antipsychotics, anticonvulsants, analgesics, hormone replacement therapies and more recently photobiomodulation. This study aims to perform a systematic review with meta-analysis in order to determine the effect of photobiomodulation on pain relief and the oral health-related quality of life associated with this condition. A bibliographical search of the Pubmed, Embase, Web of Science and Scopus databases was conducted. Only randomised clinical trials were included. Pain and quality of life were calculated as mean difference and pooled at different treatment points (baseline = T0 and final time point = Tf) and laser modality. From a total of 103 records, 7 articles were retrieved for inclusion. PBM group had a greater decrease in pain than control group at Tf with a mean difference = - 2.536 (IC 95% - 3.662 to - 1.410; I2 = 85.33%, p < 0.001). An improvement in oral health-related quality of life was observed in both groups, although this was more significant in the photobiomodulation group mean difference = - 5.148 (IC 95% - 8.576 to - 1.719; I2 = 84.91%, p = 0.003). For the red laser, a greater improvement than infrared was observed, in pain, mean difference = - 2.498 (IC 95% - 3.942 to - 1.053; I2 = 79.93%, p < 0.001), and in quality of life, mean difference = - 8.144 (IC 95% - 12.082 to - 4.206; I2 = 64.22%, p = 0.027). Photobiomodulation, in particular, red laser protocols, resulted in improvement in pain and in quality of life of burning mouth syndrome patients.

Prognostic value of CAIX expression in oral squamous cell carcinoma: a systematic review and meta-analysis.

Carbonic anhydrase IX (CAIX) is a hypoxia-related protein considered as a predictor for oral squamous cell carcinoma (OSCC) biological behaviour. Nevertheless, this prognostic value is still yet to be validated. We aim to quantify prognostic significance of CAIX overexpression in OSCC by meta-analysis. We performed searches in MEDLINE, EMBASE, SCOPUS, WOS, WHO'S databases, CPCI, and OATD from inception to August 2019. Overall survival (OS), disease-free survival (DFS), locoregional control (LC), and disease-specific survival (DSS) were considered as outcomes of interest. Overall 18 studies were included. CAIX overexpression was associated with worse OS (hazard ratio [HR] = 1.45 95% confidence interval [CI] 1.17-1.80) and DFS (HR = 1.98 95% CI 1.18-3.32). To the contrary, it was neither associated with LC (HR = 1.01 95% CI 0.50-2.02) nor with DSS (HR = 1.35 95% CI 0.78-2.33). Heterogeneity was negligible in all analyses except for DSS. Small studies effect was not significant for OS and DFS. This study shows that immunohistochemical CAIX assessment is a useful OSCC prognostic biomarker.

Using a repositioning splint to determine reproducibility in the color registers of a dental spectrophotometer.

OBJECTIVES: The purpose of this study was to assess if the use of intraoral positioning guides could increase the reproducibility of color measurements with a dental spectrophotometer. METHODS: Twenty-three subjects were selected, and positioning guides for the maxillary arch of each participant were fabricated with clear 4 mm thermo-sheets. One orifice was made in the center of the clinical crown of the upper-right central incisor and another in the canine, with an external 6 mm diameter trephine. Color measurements were performed with a Vita EasyShade Compact IV dental spectrophotometer by the same operator in the same conditions. Forty measurements were taken per patient, 20 for each tooth, 10 with a positioning guide, and 10 without one. Before each measurement, the spectrophotometer was calibrated following the manufacturer's instructions. RESULTS: Using the Wilcoxon test to evaluate nonparametric variables, there are statistically significant differences (P < .05) between the use or not of positioner for color recording with spectrophotometer. Greater repeatability of the measurements is obtained using repositioning split. CONCLUSIONS: Within the limitations of this study, the use of positioning guides provides greater reproducibility in spectrophotometer measurements for all parameters of tooth 11 and for some parameters of tooth 13. CLINICAL SIGNIFICANCE: The use of a positioning guide for color measurement with a dental spectrophotometer allows a greater reproducibility of the measurements to be obtained. Achieving repeatable measurements is essential for studying the same area of the tooth, for example, in bleaching treatments and in color checks for prosthetic treatments.

Exosomes in head and neck cancer. Updating and revisiting.

Exosomes have gone from being considered simple containers of intracellular waste substances to be considered important carriers of cellular signals. Its broad capacity to promote tumour growth, both in situ and metastatic, has greatly intensified scientific research on them. In the same way and depending on its content, its tumour suppressive properties have opened a window of light and hope in the fight against cancer. In the present review we try to gather in a simple and understandable way the most relevant knowledge to date on the role of exosomes in oral squamous cell carcinoma, helping to understand their process of formation, release and activity on the tumour microenvironment.

A Pilot Clinical Study on the Prognostic Relevance of Plasmatic Exosomes Levels in Oral Squamous Cell Carcinoma Patients.

BACKGROUND: To evaluate the relationship between the plasmatic CD63 and CAV1 positive exosome levels, in patients with OSCC before and after surgical treatment and to correlate it with their overall survival. METHODS: A double-blind pilot study over 10 patients OSCC and T4 stage without distant metastases or local bone invasion has been performed. The average follow-up period was 37.64 months (34.3⁻40.84). We obtained 2 plasma tubes of 1 mL each before surgery and 7 days after surgery. Before performing the immunocapture-based analysis, EVs (Extracellular Vesicles) were isolated from the plasma and characterized with western blot analysis. RESULTS: Mean values of CD63 positive plasmatic exosomes (EXO-CD63) after surgery decreased from 750.88 ± 286.67 to 541.71 ± 244.93 (p = 0.091). On the other hand, CAV-1 positive plasmatic exosomes (EXO-CAV-1) increased after surgery from 507 ± 483.39 to 1120.25 ± 1151.17 (p = 0.237). Patients with EXO-CD63 levels lower than the mean global value before the surgery had a survival of 36.04 months compared with the group with EXO-CD63 higher than the average who only survived 12.49 ± 1.67 months from the diagnosis, p = 0.225. When EXO-CAV-1 levels before surgery was lower than the average (813.94 ± 801.21) overall survival was 24.69 ± 22.23 months in contrast when it was higher that was only 11.64 months, p = 0.157. Patients with lower EXO-CD63 levels after surgery lived an average of 23.84 ± 23.9 months, while those with higher plasmatic levels of EXO-CD63 live 13.35 months, p = 0.808. When EXO-CAV-1 levels after surgery were lower, the average overall survival was 20.344 ± 15.40 months, in contrast when the EXO-CAV-1 levels were higher showing rather an estimate survival expectation of 1.64 months. CONCLUSIONS: Surgical treatment induced a dramatic reduction of the plasmatic levels of exosomes expressing CD63 as early as 1 week after resection. This first result suggests that the tumour mass is responsible of the high levels of circulating exosomes detected in cancer patients. At the same time point exosome expressing CAV-1 increased, possibly due to the inflammatory reaction immediately after surgery. Lastly, statistical analysis showed that lower levels of plasmatic exosomes both before and after surgery correlated with a better life expectancy of OSCC patients. Hopefully, this approach will prove useful in the clinical follow-up of cancer patients.

Evaluation of a new tricalcium phosphate for guided bone regeneration: an experimental study in the beagle dog.

This study compared the in vivo behavior of two biomaterials, xenograft (Bio-Oss®) and alloplastic tricalcium phosphate (Sil-Oss®), vs a control (no biomaterial) in beagle dogs treated with guided bone regeneration (GBR). Six male adult beagle dogs were included. The third and fourth mandibular premolars and first mandibular molars (3P3, 4P4 and 1M1) on both sides were extracted. After 12 weeks of healing, Straumann implants (3.3 × 8 mm) were placed, performing standardized defects (3.3 × 6 mm) in the vestibular aspect of the alveolar bone. The defects were surgically treated by randomized placement of xenograft (Bio-Oss®), alloplastic tricalcium phosphate (Sil-Oss®) or no biomaterial and covered with a resorbable collagen membrane (BioGide®). After an additional 12-week healing period, the lower jaws were dissected. Total area regenerated in the region of interest, total volume, bone to implant contact in the regenerated area, and volumetric changes were measured through histological, histomorphometrical and microcomputed tomography (microCT) techniques. The negative control group showed bone ingrowth inside the defect, with a partial collapse of the buccal bone. This was not observed in the biomaterial-treated groups. Defects treated with the xenograft showed 51.40% (SD 19.83) newly mineralized tissue, while those treated with alloplastic tricalcium showed 62.54% (SD 11.54) newly mineralized tissue; the control showed 71.52% (SD 6.46). Alloplastic tricalcium phosphate modified with monetite and zinc showed similar features in alveolar regeneration of defects to those treated with the xenograft or conventional GBR, but it showed an ideally higher rate of new mineralized tissue formation and accelerated resorption.

20 years of alveolar distraction: A systematic review of the literature

BACKGROUND: The Vertical Alveolar Distraction Osteogenesis (VADO) technique is an excellent solution for bone and soft tissue neoformation in areas in which there has been significant bone atrophy that hinders normal rehabilitation using dental implants. The goal of this systematic review is to analyze the most relevant articles published on VADO in the literature over the past 20 years. MATERIAL AND METHODS: The review was performed by using the keywords: "alveolar ridge", "distraction ostegenesis" and "dental implant". This search produced a total result of 240 articles. The clinical studies and cases reported in humans amounted to 113 articles, 18 articles referred to studies developed on animals and 33 review articles. The presentation of this systematic analysis follows the criteria described in the PRISMA declaration. RESULTS: 22 articles complied with the inclusion criteria and 7 articles more were added manually, reaching a total sample of 29 studies. Following the analysis of the studies, they were classified into 18 high-quality, 10 mediumquality and 1 low-quality study. Only 4 studies achieved a maximum score of 9 (according to NewCastle Ottawa Scale, NOS). CONCLUSIONS: VADO is a technique with greater potential in vertical gain. The performance of dental implants has a success and survival rate similar to dental implants placed on bones that are not subject to increase techniques

Survival study of leukoplakia malignant transformation in a region of northern Spain

BACKGROUND: Oral leukoplakia is the most common potentially malignant disorder (PMD) of the oral cavity. The objectives of this study are to determine the clinicopathologic features in a group of patients with oral leukoplakia of Northern Spain (Galicia), determining the factors associated to clinical risk and analyzing the malignant transformation of these patients. MATERIAL AND METHODS: We included 85 patients. We recorded sex and age, habits like alcohol and tobacco, size, clinical appearance, site, number of lesions, and presence or absence of dysplasia. We assess the association between risk factors and transformation and developed a logistic regression analysis. Finally we used the Kaplan-Meier and log-rank test for the survival analysis. RESULTS: 7 patients (8.2%) had malignant transformation. The mean follow-up of the patients was 4.13 years versus 5.58 years of those who developed carcinoma. Only location and initial dysplasia have a statistically significant relationship with malignant transformation, but when applied the long rank test only the presence of dysplasia remains statistically significant (P<0,026). Oral Cancer Free Survival was 81.9% (0.150) at 11 years for the group without dysplasia. CONCLUSIONS: We found that the presence of dysplasia is the only risk factor that is statistically related to the development of a carcinoma

Differential expression of snoRNAs in oral squamous cell carcinomas: new potential diagnostic markers.

BACKGROUND: Small nucleolar RNAs (snoRNAs) are small non-coding RNA sequences whose most studied function is ribosome biogenesis. The altered expression of snoRNA is observed in tumoral processes such as breast cancer and multiple myeloma. However, we have not found any references to snoRNAs in oral squamous cell carcinomas (OSCC) in the literature at the time this article was written. MATERIAL AND METHODS: We have analyzed snoRNA expression in frozen OSCC tissue samples and have compared them to healthy controls. RNA was extracted from a total of eight OSCC samples and eight control samples, measuring the differential expression of small RNAs with the Affymetrix® miRNA 4.1 Array Plate microarray platform. RESULTS: Results were analyzed using the Transcriptome Analysis Console 3.0 (TAC) software. We obtained a total of 16 deregulated snoRNAs of which one was over expressed and 15 were under expressed. SnoRNAs expression was altered in OSCC and could serve as a diagnostic marker.

Update in the extraction of airway foreign bodies in adults.

Foreign body (FB) aspiration into the airway is lees common in adults than children. Nevertheless its incidence does not decrease through time. We present clinical relevant aspects of airway FBs on the basis of a selective review of pertinent literature retrieved by a search in the PubMed database. The most common aspirated FBs by adults are organics, especially fragments of bones and seeds. Symptoms usually are cough, chocking and dyspnea. Right localization, especially bronchus intermedius and right lower lobe, is more frequent. Chest radiography can be normal in up to 20% of the cases and FBs can be detected in 26% of the patients. FBs can safely remove in the majority of patients under flexible bronchoscopy. Surgical treatment must be reserved for cases in which bronchoscope fails or there are irreversible bronchial or lung complications.

Radiological infrabony defects after impacted mandibular third molar extractions in young adults.

PURPOSE: To estimate the prevalence of infrabony defects and their healing at the distal aspect of mandibular second molars (M2s) after extraction of impacted mandibular third molars (M3s). MATERIALS AND METHODS: This prospective clinical study included 22 young healthy patients (21.03 ± 4.51 yr old). Thirty-seven surgical extractions of high-risk periodontal and mesioangular impacted M3s in close contact with adjacent M2s were performed. Radiographic bone height (RBH), radiographic infrabony defects (RIDs), and bone loss (BL) were recorded at baseline and 3, 6, and 12 months after surgery. RBH and RIDs were measured from the tip of a periodontal gauge to the root apex and to the cementoenamel junction of the M2, respectively; BL was calculated by dividing the length of the M2 root into thirds and categorized as slight, moderate, or severe. RESULTS: Only 26 extracted teeth were included in all radiographic assessments. Mean RID size at baseline was 4.54 ± 1.87 mm. At 12 months, an average recovery of 2.80 ± 2.36 mm (P < .001) was recorded, for a mean RID size of 1.78 ± 1.65 mm. Statistically significant differences in RBH and RIDs were found at all assessments (P < .05). Improved bone healing was registered during the postoperative period, with higher values during the first 3 months (1.3 mm; P < .01). Most RIDs of at least 4 mm associated with moderate or slight BL decreased to no larger than 3 mm without BL. For moderate BL, the bone gain pattern was gradual and continuous, whereas for slight BL, the pattern was variable. CONCLUSIONS: In young healthy patients, a high-risk periodontal impacted M3 leads to an RID of at least 4 mm associated with slight or moderate BL at the distal aspect of the M2, which decreases to no larger than 3 mm 12 months after surgery. Bone healing is clinically and statistically significant at 12 months, with the most notable changes at the first 3-month follow-up.

Mandibular second molar periodontal healing after impacted third molar extraction in young adults.

PURPOSE: To estimate the prevalence of preoperative periodontal defects and analyze 12-month spontaneous healing on the distal aspect of the mandibular second molar (M2) after impacted mandibular third molar (M3) extraction. MATERIALS AND METHODS: This prospective clinical study was conducted in 25 healthy young patients (21.03 ± 4.38 yr old) with 40 extractions of higher-risk periodontal impacted M3s. Plaque and gingival indexes, recession, bleeding on probing, probing depth (PD), and attachment level were recorded before surgery and at 3, 6, and 12 months after surgery at 5 sites on the distal aspect of the M2. RESULTS: The initial mean PD was 5.70 ± 3.80 mm, with the deepest mean PD at the lingual side. At 12 months, a mean PD average of 3.77 ± 2.86 mm was recorded, with a total average recovery of 1.93 ± 2.46 mm (P < .001), that was higher at 3 months (-1.62 mm, P < .001). The PD and attachment level improvements were statistically significant (P < .001) and nearly clinically significant from baseline to 12-month follow-up and from the buccal to the lingual side of the distal aspect of the M2. CONCLUSIONS: Impacted M3s adjacent to M2s lead to periodontal defects that are deepest at the lingual side and almost recover at 12 months after extraction. The first 3 months is considered the cutoff for periodontal healing. Young adults with high-risk periodontal M3 impactions may benefit from early extraction, which increases spontaneous periodontal healing.

Predictive factors for maxillary sinus augmentation outcomes: a case series analysis.

AIM: To determine the influence of different local and systemic factors on histologic, histomorphometric, and radiographic outcomes after maxillary sinus augmentation. MATERIALS AND METHODS: Fifty-two sinus augmentation procedures were performed. Grafting material consisted of a mixture of anorganic bovine bone (ABB) and autogenous bone. After 6 months, bone core biopsies were harvested from implant sites for histologic and histomorphometric analyses. Data regarding age, gender, type of edentulism, alcohol consumption, smoking habits, and history of periodontal disease were recorded and statistically analyzed. RESULTS: Histomorphometric analyses revealed the presence of 35.75% ± 16.42% of vital bone, 40.56% ± 16.23% of nonmineralized tissue, and 23.69% ± 18.23% of residual ABB particles. Radiographic vertical bone resorption inversely correlated with residual ABB. A significant difference in bone resorption patterns was observed for completely edentulous patients and for those with a history of periodontitis. Tobacco and alcohol negatively influenced vital bone formation after sinus augmentation. Implant and prostheses survival after 2 years of functional loading was not directly affected by patient's individual habits. CONCLUSION: Certain patient-related variables such as history of periodontitis, type of edentulism, or smoking/drinking habits play an important role in bone graft maturation after maxillary sinus floor elevation.

A modified device for intraoral radiography to assess the distal osseous defects of mandibular second molar after impacted third molar surgery

PURPOSE: This article is to describe a modified device for intraoral radiography which was developed to obtain reproducible radiographic images for assessment of distal osseous defects of the mandibular second molar (2 Mm) after impacted third molar (3 Mm) surgery. MATERIALS AND METHODS: A commercial available alignment system for posterior region was modified by adding a reference gauge pin (millimetric) and threading a hollow acrylic cylinder at the ring of the radiographic positioner to attach the X-ray collimator. The design included customized resin acrylic stent for the occlusal surface of the 2Mm in maximum intercuspal position, individualizing the biteblock positioner. Periapical radiographs were taken before and after surgical extraction of 3 Mm, employing the radiographic technique of parallelism described by Kugelberg (1986) with this modified film holder and inserting the gauge pin on the deepest bone probing depth point. RESULTS: This technique permitted to obtain standardized periapical radiographs with a moderate to high resolution, repeatability, and accuracy. There was no difference between the measurements on the pre- and post-operative radiographs. This technique allowed better maintenance of the same geometric position compared with conventional one. The insertion of the gauge pin provided the same reference point and localized the deepest osseous defect on the two-dimensional radiographs. CONCLUSION: This technique allowed better reproducibility in posterior radiographic records (distal surface of 2 Mm) and more accurate measurements of radiographic bone level by the use of a millimetric pin.

A three-dimensional computer model of the human mandible in two simulated standard trauma situations.

PURPOSE: A three-dimensional finite element model of the human mandible was developed to simulate and analyse biomechanical behaviour in two standard trauma situations. This computer-based study was made to assess the stress patterns within human mandibles generated by impact forces. MATERIAL AND METHODS: The mandibular model was generated using 7.073 nodes and 30.119 tetrahedra. A commercial finite element solver was then applied to this mesh to compute stresses generated in standard trauma situations (a blow in the symphysis region and another one to the body of the mandible). RESULTS: The results indicate that following a blow to the symphysis region, maximum stress areas were located at the symphysis, retromolar and condylar regions. In the case of a blow to the mandibular body, the maximum stress areas were located at the contralateral angle, the ipsilateral body and the ipsilateral condylar neck regions. CONCLUSION: The main application of this study was the prediction of fractures as a consequence of known forces.