Anatomical characteristics of maxillary sinus antroliths and their influence on sinus membrane thickness: a retrospective cone beam computed tomography analysis

The purpose of this study was to assess the anatomy of antroliths and its influence on the thickness of the maxillary sinus membrane. Cone beam computed tomography (CBCT) was performed on 239 patients (478 sinuses). The prevalence of antroliths per sinus was 8.4%. Regarding their distribution, antroliths were predominantly unilateral (82.5%), single (67.5%), and in a dentate area (60.0%). The antroliths were mainly located in the molar region (95.0%) and in the sinus floor (77.5%). The measured dimensions of the antroliths were as follows: length 5.6 ± 4.4 mm, width 4.1 ± 2.9 mm, height 3.5 ± 2.1 mm. The relationships between the antroliths and the sinus membrane (type 1, 34.1%; type 2, 52.3%; type 3, 13.6%) indicated that sinus membranes tended to encircle antroliths, which resulted in a gradual increase in membrane thickness. The sinus membrane was found to be significantly thicker in the presence of antrolith(s) (P < 0.001). Antroliths which are sufficiently large or are located adjacent to the sinus floor or lateral wall increase the risk of sinus membrane perforation during sinus augmentation procedures. Therefore, a thorough CBCT evaluation is needed to minimize the risk of complications prior to sinus augmentation procedures.     

Volumetric CBCT analysis of the palatine process of the anterior maxilla: a potential source for bone grafts

The aim of this research was to use cone-beam computerized tomography (CBCT) to analyze the available bone volume in the palatine process of the maxilla (PPM), which is a potential source of bone grafts. 20 CBCT scans were evaluated. From the most caudal axial slice of the PPM, the bony surface was calculated cranially up to the nasal floor. The predetermined thickness of each slice was 0.9 mm. A 2 mm safety margin was established considering the incisive canal and teeth 14–24. A ±0.1 mm error deviation was established for all calculations. By connecting these points and those defined at the posterior bone boundary, a surface was obtained. A three-dimensional (3D) image of the delimited zone was constructed and analyzed using 3D imaging software. The study comprised 6 women and 14 men (mean age 39.4 ± 11.5 years). Calculated bone volume averaged 2.41 ± 0.785 cm³. The palatine process of the maxilla contains a considerable bone volume (2.41 ± 0.785 cm³). This area should be regarded as a potential donor site for the regeneration of maxillary atrophic bones. Further investigation is required before these findings lead to routine clinical application.     

Apical U-shape splitting technique for undercut areas of the anterior alveolar ridge: a prospective non-randomized controlled study

The aim of this study was to investigate a novel apical U-shape splitting technique for horizontal bone augmentation in undercut areas and to compare its efficacy with that of guided bone regeneration (GBR). This was a prospective non-randomized controlled clinical trial. A total of 36 patients, who presented with a labial undercut that was not able to house a normally inclined implant, underwent the new technique or GBR. Radiographic and clinical data were obtained preoperatively, immediately after surgery, and 12 months after surgery. Pairwise comparisons of changes in ridge width gain, marginal bone loss, and pink aesthetic score were performed; correlations with pristine ridge morphology were investigated. The results showed similar marginal bone loss in the two groups. The overall ridge width gains in the new technique group (2.56 ± 1.92 mm) and GBR group (0.73 ± 1.21 mm) differed significantly (P < 0.05). The pink aesthetic score was higher for the new technique group (11.75 ± 1.22) than for the GBR group (9.25 ± 1.86) (P < 0.01). The morphology of the concavity had different impacts on regeneration in the two groups. The apical U-shape splitting technique, as a safe and effective alternative to GBR, provided a significant increase in bone volume gain where labial fenestration was inevitable during implant placement.     

Association between hypoplastic condyles and temporomandibular joint disc displacements: a cone beam computed tomography and magnetic resonance imaging metrical analysis

This study investigated the association between hypoplastic condyles and disc displacements without reduction (DDw/oR). Consecutive patients with non-syndromic unilateral condylar hypoplasia were recruited and clinical, cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI) data were acquired. Linear measurements including condylar head width, depth, height and condyle length were determined with CBCT while MRI was used to assess disc position, morphology and displacement. A total of 43 patients were enrolled of which 93.02% had a history of temporomandibular disorders (TMDs) and 83.72% presented with TMD signs and symptoms. Depth and height of the condylar head along with condyle length of hypoplastic joints (6.68 ± 1.67 mm, 4.97 ± 1.25 mm and 14.49 ± 3.02 mm, respectively) were significantly lesser than normal joints (7.77 ± 1.26 mm, 6.35 ± 1.45 mm and 18.20 ± 3.18 mm) (P < 0.001). The prevalence of DDw/oR was significantly higher in hypoplastic joints (79.07% versus 13.95%) (P < 0.001). Joints with hypoplastic condyles had shorter disc lengths (6.99 ± 2.16 mm vs, 8.45 ± 2.26 mm) (P = 0.007). Furthermore, disc displacements were significantly more advanced (8.52 ± 2.84 mm) and severe (76.74% with severe translations) when compared to the contralateral side (4.77 ± 2.97 mm and 32.56%) (P < 0.05). A significant association was observed between condylar hypoplasia and temporomandibular joint DDw/oR with hypoplastic joints exhibiting more severely displaced and deformed discs. DDw/oR coupled with repaired degenerative joint disease may mimic condylar hypoplasia radiographically.     

Influence of platelet rich fibrin on post-extraction socket healing: A clinical and radiographic study

Aim

The aim of this study was to evaluate clinically and radiographically, extraction socket healing using autologous platelet rich fibrin (PRF).

Early implant placement and peri-implant augmentation with a porcine-derived acellular dermal matrix and synthetic bone in the aesthetic area: a 2-year follow-up prospective cohort study

The aim of this study was to evaluate the 2-year follow-up results of early implant placement with simultaneous peri-implant augmentation using an acellular dermal matrix (ADM) and a synthetic bone substitute in the aesthetic zone. Twenty subjects were enrolled in this study, they were either males (eight) or females (12), with a mean age of 47.8 ± 4.45 years and each patient was treated with one implant. Simultaneous contour augmentation with guided bone regeneration was performed using synthetic bone particles (maxresorb®) and an ADM (mucoderm®). Keratinized mucosa width (KMW) and gingival thickness (GT) were assessed at baseline, 1, 3, 6, 12 and 24 months. Marginal bone loss, probing pocket depth, bleeding on probing and plaque index were also recorded. GT and KMW increased between baseline and 1 month, slightly decreased between 1 month and 12 months (P < 0.001) and remained stable between 12 and 24 months (P < 0.001). After 2 years, mean marginal bone loss level was 0.51 ± 0.63 mm, with no probing pocket depth values >5 mm and no concomitant signs of inflammation registered. Pink aesthetic score was 8.3. Combining an ADM and guided bone regeneration with early implant placement revealed a significant increase of 1.9 mm for GT and 1.6 mm for KMW after 2 years, showing good patient satisfaction regarding the aesthetic outcomes of soft tissues and prosthetic crown.     

Simulation of sinus floor augmentation with symphysis bone graft using three-dimensional computerized tomography

The objective of this study was to evaluate the maximum amount of harvestable bone graft in the mandibular symphysis and the augmentation volume needed for different sinus lift levels (from 10 to 18 mm), in addition to calculating which sinus lift level can be acquired using the individual's symphysis bone graft volume with three-dimensional computerized tomography (3D CT) and software. Data from 15 CT scans was obtained from 15 adult patients (10 males, five females). The CT data, in DICOM format, was read into Mimics software from Materialize (Leuven, Belgium), with a slice thickness of 0.5 mm. The mandibular symphysis bone graft volumes and different levels of sinus lift augmentation volumes were calculated on the 3D images using Mimics software. It was determined that the average symphysis bone volume (3491.08 ± 772.12 mm³) could provide approximately 14 mm of sinus lift height (3167.84 ± 1067.65). 3D CT techniques and software can be used to calculate the required graft volume for sinus floor augmentation and symphysis bone graft volume, and the mandibular symphysis region can provide adequate bone volume for sinus lift augmentation.     

Digital replacement of the distorted dentition acquired by cone beam computed tomography (CBCT): a pilot study

During cone beam computed tomography (CBCT) scanning, intra-oral metallic objects may produce streak artefacts, which impair the occlusal surface of the teeth. This study aimed to determine the accuracy of replacement of the CBCT dentition with a more accurate dentition and to determine the clinical feasibility of the method. Impressions of the teeth of six cadaveric skulls with unrestored dentitions were taken and acrylic base plates constructed incorporating radiopaque registration markers. Each appliance was fitted to the skull and a CBCT performed. Impressions were taken of the dentition with the devices in situ and dental models were produced. These were CBCT-scanned and the images of the skulls and models imported into computer-aided design/computer-aided manufacturing (CAD/CAM) software and aligned on the registration markers. The occlusal surfaces of each dentition were then replaced with the occlusal image of the corresponding model. The absolute mean distance between the registration markers in the skulls and the dental models was 0.09 ± 0.02 mm, and for the dentition was 0.24 ± 0.09 mm. When the method was applied to patients, the distance between markers was 0.12 ± 0.04 mm for the maxilla and 0.16 ± 0.02 mm for the mandible. It is possible to replace the inaccurate dentition on a CBCT scan using this method and to create a composite skull which is clinically acceptable.     

Nasolabial soft tissue effects of segmented and non-segmented Le Fort I osteotomy using a modified alar cinch technique—a cone beam computed tomography evaluation

The aim of this study was to verify soft tissues changes and the effect of a minimally invasive surgical technique in the nasolabial region after segmented and non-segmented Le Fort I osteotomy, using cone beam computed tomography (CBCT) evaluation of three-dimensional (3D) volume surfaces. Two groups were evaluated: group 1, bimaxillary surgery with maxillary segmentation (n = 40); group 2, bimaxillary surgery without maxillary segmentation (n = 40). In both groups, a specific alar cinching technique was used to control nasal base broadening. CBCT evaluation was performed at three different treatment time points: T0, 1 month before surgery; T1, 1 month after surgery; T2, 1 year after surgery. The results showed statistically significant differences in the nasolabial area (P < 0.001). For group 1, the mean change in alar base width (Al_inf–Al_inf) was 1.31 ± 1.40 mm at T1 and 0.93 ± 1.77 mm at T2; for group 2 these values were 1.12 ± 2.01 mm at T1 and 0.54 ± 1.54 mm at T2. For group 1, the mean changes in inter-alar width (Al–Al) were 1.68 ± 1.46 mm at T1 and 1.49 ± 1.33 mm at T2; for group 2, they were 2.22 ± 1.93 mm at T1 and 1.34 ± 1.79 mm at T2. The alar cinch technique proposed here appears to be effective in controlling nasolabial soft tissue widening.     

Skeletal,dental and facial aesthetic changes following anterior maxillary segmental distraction by tooth-borne device in patients with cleft lip and palate

Maxillary skeletal deficiency secondary to cleft lip and palate (CLP) remains a significant challenge. The aim of this study was to present the comprehensive skeletal, dental and facial aesthetic outcomes of anterior maxillary segmental distraction osteogenesis (AMSDO) for treatment of maxillary hypoplasia in patients with CLP. Twelve patients with maxillary hypoplasia treated with AMSDO by a customized tooth-borne distractor were included. Three-dimensional changes of anterior maxillary segment, upper incisor and pharyngeal space were measured by three-dimensional reconstruction derived from cone beam computed tomography (CBCT) data. Length and width of dental arch during distraction were determined in dental casts. Nasolabial angle, soft-tissue convexity and patient’s subjective satisfaction were assessed to evaluate facial aesthetic improvements. Nasopharyngoscopic evaluation and speech assessment were also performed before and after distraction. All patients successfully received AMSDO without serious complications. Following AMSDO, the anterior maxillary segments moved forward 5.56 ± 0.28 mm and slightly upward 1.15 ± 0.13 mm. AMSDO significantly lengthened maxillary dental arch, generated new bone to relieve dental crowding and improved patients’ facial aesthetic without worsening velopharyngeal closure and speech quality. AMSDO by tooth-borne distractor is an effective surgical alternative for the advancement in patients with cleft maxillary hypoplasia.     

Accuracy of implant position when placed using static computer-assisted implant surgical guides manufactured with two different optical scanning techniques: a randomized clinical trial

Data from cone beam computed tomography (CBCT) and optical scans (intraoral or model scanner) are required for computer-assisted implant surgery (CAIS). This study compared the accuracy of implant position when placed with CAIS guides produced by intraoral and extraoral (model) scanning. Forty-seven patients received 60 single implants by means of CAIS. Each implant was randomly assigned to either the intraoral group (n = 30) (Trios Scanner, 3Shape) or extraoral group (n = 30), in which stereolithographic surgical guides were manufactured after conventional impression and extraoral scanning of the stone model (D900L Lab Scanner, 3Shape). CBCT and surface scan data were imported into coDiagnostiX software for virtual implant position planning and surgical guide design. Postoperative CBCT scans were obtained. Software was used to compare the deviation between the planned and final positions. Average deviation for the intraoral vs. model scan groups was 2.42° ± 1.47° vs. 3.23° ± 2.09° for implant angle, 0.87 ± 0.49 mm vs. 1.01 ± 0.56 mm for implant platform, and 1.10 ± 0.53 mm vs. 1.38 ± 0.68 mm for implant apex; there was no statistically significant difference between the groups (P > 0.05). CAIS conducted with stereolithographic guides manufactured by means of intraoral or extraoral scans appears to result in equal accuracy of implant positioning.     

Effects of Choukroun’s platelet-rich fibrin on bone regeneration in combination with deproteinized bovine bone mineral in maxillary sinus augmentation: A histological and histomorphometric study

PurposeThe potential effect of Choukroun’s platelet-rich fibrin (PRF) in combination with allograft on promoting bone regeneration has been discussed in previous publications. This study aims to evaluate an influence of PRF on bone regeneration in sinus augmentation in combination with a xenograft, deproteinised bovine bone.Materials and methodsEleven sinuses from 10 patients with posterior maxillary bone atrophy were selected for the study. As a test group, six sinus floor elevations were grafted with a Bio-Oss and PRF mixture, and as control group, five sinuses were treated with Bio-Oss alone. Clinical and radiographic examinations were performed pre- and postoperatively. After 6 months of sinus augmentation, bone biopsies were obtained from the grafted posterior maxilla, and un-decalcified ground sections were prepared. Bone characteristics were evaluated using histological observation and histomorphometric analyses.ResultsNo adverse effect was observed in any case within the follow-up period of 6 months after sinus augmentation. Histological observation showed similar morphological characteristics for both the PRF and control groups. The percentage of new bone formation in the PRF group was about 1.4 times of that in control (18.35% ± 5.62% vs. 12.95% ± 5.33%), while the percentage of residual bone substitute in the control group was about 1.5 times higher as that in the PRF group (28.54% ± 12.01% vs. 19.16% ± 6.89%). The percentage of contact length between newly formed bone and bone substitute in the PRF group was 21.45% ± 14.57% vs. 18.57% ± 5.39% in the control. No significant statistical differences between the two groups were found in these observed parameters.ConclusionsOur preliminary result demonstrated neither an advantage nor disadvantage of the application of PRF in combination with deproteinised bovine bone mineral in sinus augmentation after a healing period of 6 months.     

Dental image replacement on cone beam computed tomography with three-dimensional optical scanning of a dental cast,occlusal bite,or bite tray impression

The goal of the present study was to compare the accuracy of dental image replacement on a cone beam computed tomography (CBCT) image using digital image data from three-dimensional (3D) optical scanning of a dental cast, occlusal bite, and bite tray impression. A Bracket Typodont dental model was used. CBCT of the dental model was performed and the data were converted to stereolithography (STL) format. Three experimental materials, a dental cast, occlusal bite, and bite tray impression, were optically scanned in 3D. STL files converted from the CBCT of the Typodont model and the 3D optical-scanned STL files of the study materials were image-registered. The error range of each methodology was measured and compared with a 3D optical scan of the Typodont. For the three materials, the smallest error observed was 0.099 ± 0.114 mm (mean error ± standard deviation) for registering the 3D optical scan image of the dental cast onto the CBCT dental image. Although producing a dental cast can be laborious, the study results indicate that it is the preferred method. In addition, an occlusal bite is recommended when bite impression materials are used.     

Bone regeneration at the distal aspect of the adjacent second molar after lower third molar coronectomy: a long-term analysis

A residual bone defect at the distal aspect of the adjacent second molar may occur after total removal of the lower third molar. Lower third molar coronectomy has been proved to be a safe alternative to total removal, but the extent of bone regeneration at the adjacent tooth after coronectomy is not well reported. The aim of this prospective study was to investigate the long-term bone regeneration at the distal aspect of the adjacent second molar after lower third molar coronectomy. Preoperative and postoperative cone beam computed tomography scans were measured to assess bone regeneration at the distobuccal (DB), mid-distal (MD), and distolingual (DL) aspects of the lower second molar. Forty-eight coronectomies in 37 patients (23 female) with a mean ± standard deviation age of 29.1 ± 7.2 years were assessed. The mean follow-up was 93.2 ± 8.7 months. The mean bone level increase at DB, MD, and DL aspects was 3.2 ± 1.6 mm, 3.5 ± 1.5 mm, and 3.2 ± 1.6 mm, respectively; the bone levels were significantly higher than the preoperative measurements (P < 0.001). Age and impaction patterns were not factors affecting bone regeneration. Based on this study, it appears that coronectomy of the lower third molar brings favourable bone regeneration at the distal aspect of the adjacent second molar.     

Soft tissue-based registration of intraoral scan with cone beam computed tomography scan

The aim of this study was to evaluate a novel soft tissue-based method to register an intraoral scan (IOS) with a cone beam computed tomography (CBCT) scan. IOS and CBCT data were obtained from eight dentate patients (mean age 21 ± 2 years; three male, five female) and 14 fully edentulous patients (mean age 56 ± 9 years; eight male, six female). An algorithm was developed to create a soft tissue model of the CBCT scan, which allowed a soft tissue-based registration to be performed with the IOS. First, validation was performed on dentate jaws with registration of the palatal mucosal surface and accuracy evaluation at the level of the teeth. Second, fully edentulous jaws were registered using both the palatal and alveolar crest mucosal surfaces. Distance maps were created to measure the method accuracy. The mean registration error was 0.49 ± 0.26 mm for the dentate jaws. Registration of the fully edentulous jaws had a mean error of 0.16 ± 0.08 mm at the palate and 0.16 ± 0.05 mm at the alveolar crest. In conclusion, the high accuracy of this registration method may allow the digital workflow to be optimized when no teeth are available to perform a regular registration procedure.     

In vitro evaluation of conventional and locking miniplate/screw systems for the treatment of mandibular angle fractures

This in vitro study evaluated the influence of the type of miniplate and the number of screws installed in the proximal and distal segments on the stability and resistance of Champy's osteosynthesis in mandibular angle fractures. Sixty polyurethane hemimandibles with bone-like consistency were randomly assigned to four groups (n = 15) and sectioned in the mandibular angle region to simulate fracture. The bone segments were fixed by different osteosynthesis methods using 2.0 mm miniplates and 2.0 mm × 6 mm monocortical screws. In groups 1 and 2, two conventional (G1) or locking (G2) screws were installed in each bone segment using a conventional (G1) or a locking (G2) straight miniplate; in groups 3 and 4, three conventional (G3) or locking (G4) screws were installed in the proximal segment and four conventional (G3) or locking (G4) screws were installed in the distal segment using a conventional (G3) or a locking (G4) seven-hole straight miniplate. The hemimandibles were loaded in compressive strength until a 4 mm displacement occurred between the segments, vertically or horizontally. Locking plate/screw systems provided significantly greater resistance to displacement than conventional ones (p < .01). Locking miniplates offered more resistance than conventional miniplates. Long locking miniplates provided greater stability than short ones.     

Assessment of condylar changes after orthognathic surgery using computed tomography regional superimposition

This study aimed to investigate the effects of bimaxillary advancement orthognathic surgery on the condylar remodeling of the temporomandibular joint (TMJ) using voxel-based regional superimposition of cone-beam computed tomography (CBCT).In this retrospective study, the sample comprised 56 condyles from 28 healthy patients (aged from 16 to 50 years) with mandibular retrognathism treated with bimaxillary advancement. CBCT scans were taken preoperatively and at 14.3 ± 4.2 months postoperatively. The scans at the two time points were superimposed using regional voxel-based registration to assess condylar changes in the follow-up period. The linear alterations were measured in six different areas of each condyle to determine the pattern of condylar remodeling.Although no significant correlation was observed between changes in condylar surfaces, bone resorption occurred predominantly in the posterior and superior regions, while bone formation was predominantly on the anterior surface. Medial and lateral surfaces presented fewer bone changes. The overall bone changes were smaller than 1 mm bilaterally in 21 patients (75%) and, considering each condyle individually, were smaller than 1 mm in 48 condyles (85.7%).The results suggested that mild condylar remodeling in healthy patients is a common finding after orthognathic surgery. Future studies may clarify the mechanisms involved in the remodeling and help to understand the reasons for the remodeling pattern.     

A cone-beam CT based technique to augment the 3D virtual skull model with a detailed dental surface

Cone-beam computed tomography (CBCT) is used for maxillofacial imaging. 3D virtual planning of orthognathic and facial orthomorphic surgery requires detailed visualisation of the interocclusal relationship. This study aimed to introduce and evaluate the use of a double CBCT scan procedure with a modified wax bite wafer to augment the 3D virtual skull model with a detailed dental surface. The impressions of the dental arches and the wax bite wafer were scanned for ten patient separately using a high resolution standardized CBCT scanning protocol. Surface-based rigid registration using ICP (iterative closest points) was used to fit the virtual models on the wax bite wafer. Automatic rigid point-based registration of the wax bite wafer on the patient scan was performed to implement the digital virtual dental arches into the patient's skull model. Probability error histograms showed errors of ≤0.22 mm (25% percentile), ≤0.44 mm (50% percentile) and ≤1.09 mm (90% percentile) for ICP surface matching. The mean registration error for automatic point-based rigid registration was 0.18 ± 0.10 mm (range 0.13–0.26 mm). The results show the potential for a double CBCT scan procedure with a modified wax bite wafer to set-up a 3D virtual augmented model of the skull with detailed dental surface.     

Non invasive and surgical measurement of length of soft tissue from the tip of interdental papilla to the alveolar crest

BackgroundVarious methods, including clinical and radiographic techniques, can be used to assess periodontal regeneration in interproximal areas. The goal of the present study was to compare the papilla length relative to the alveolar bone crest measured by clinical, intrasurgical, and radiographic techniques.Materials and methodsThe study sample included 250 interproximal papillae in 68 patients with generalized chronic periodontitis. The papilla length from the alveolar bone crest was measured clinically (as the actual papilla length, APL), intrasurgically (as the bone probing length, BPL), and radiographically (as the radiographic bone length, RBL). Measurements were standardized by using acrylic resin stents, XCP rinn, a paralleling technique, and/or a radiographic grid.ResultsThe mean (± standard deviation) for RBL was 4.9 ± 0.8 mm, BPL was 5.1 ± 0.6 mm, and APL was 5.1 ± 0.6 mm. Correlations between RBL and APL and between BPL and APL were 0.918 and 0.943, respectively (both P < 0.01).ConclusionsIf the clinical recordings are appropriately standardized, then noninvasive radiographic methods can be used to evaluate the papilla length with good accuracy.