Bone Dimensional Change Following Immediate Implant Placement in Posterior Teeth with CBCT: A 6-Month Prospective Clinical Study.

This prospective clinical study aimed to evaluate the peri-implant hard tissue dimensional change at 6 months of immediate implant placement with bone graft materials in the posterior area using cone-beam computed tomography (CBCT). Twelve dental implants were placed concurrently following tooth extraction in the posterior area and filled with xenograft particles. The CBCT images were taken immediately after surgical procedures and then at 6 months follow-up. To evaluate the hard tissue changes, the vertical and horizontal bone thickness were analyzed and measured using ImageJ software. Paired t-test or Wilcoxon match-pair signed-rank test was done to analyze the changes of hard tissue values at the same level between immediately and 6 months following immediate implant placement. Independent t-test or Mann-Whitney U test was used to analyze the dimensional change in the vertical and horizontal direction in buccal and lingual aspects. The level of significance was set at p value = 0.05. All implants were successfully osseointegrated. At 6 months follow-up, the vertical bone change at the buccal aspect was -0.69 mm and at the lingual aspect -0.39 mm. For horizontal bone thickness, the bone dimensional changes at 0, 1, 5, and 9 mm levels from the implant platform were -0.62 mm, -0.70 mm, -0.24 mm, and -0.22 mm, respectively. A significant bone reduction was observed in all measurement levels during the 6 months after implant placement (p value < 0.05). It was noted that even with bone grafting, a decrease in bone thickness was seen following the immediate implant placement. Therefore, this technique can be an alternative method to place the implant in the posterior area.

Different Implant Subgingival Depth Affects the Trueness and Precision of the 3D Dental Implant Position: A Comparative in Vitro Study Among Five Digital Scanners and a Conventional Technique.

PURPOSE: The aim of this study was to investigate the effect of implant subgingival depth on the trueness and precision of the 3D implant position, and the effect of digital implant impression techniques on the 3D implant position. MATERIALS AND METHODS: Three resin master models were created with implant analogs submerged 3, 6, and 9 mm from the gingival margin. Four intraoral scanners (TRIOS, DWIO, Omnicam, and TruDef), one laboratory scanner (E3), and a conventional impression technique were used to take impressions of the master models, which resulted in six test models for each depth. These six impression techniques were performed six times for precision assessment. The master models were sent for high-powered micro-focused computed tomography as the gold standard control group. The scan body positions of the test models and their control models were superimposed using reverse-engineering software. The 3D distortion of the implant position in each comparison was measured by linear distortion (dx, dy, dz) and calculated as the global linear distortion (dR). RESULTS: The trueness of the mean dR values at the 3-mm, 6-mm, and 9-mm implant depths was 99 µm, 60.6 µm, and 107 µm, respectively. The least significant difference test of the impression system showed that all the digital impression techniques except the DWIO scanner had better trueness than the conventional impression technique. The 6-mm implant depth exhibited a significantly lower 3D distortion of the implant position than those of the 3-mm and 9-mm implant depths. The E3 scanner had the highest precision, while the conventional impression technique had the lowest precision. All the intraoral scanners except the DWIO scanner showed better precision than the conventional impression technique. CONCLUSION: Most of the intraoral scanners had better trueness and precision than the conventional impression technique for up to 6 mm of implant subgingival depth.

Branching patterns of the inferior alveolar canal in a Thai population: a novel classification using cone beam computed tomography.

OBJECTIVE: This aim of this study was to determine the prevalence and branching patterns of the inferior alveolar canal (IAC) in premolar and molar areas using cone beam computed tomography (CBCT). METHOD AND MATERIALS: CBCT volumes from partially or fully edentulous premolar and molar areas were investigated retrospectively. The presence of such branches with their patterns, sides, and areas, as well as the sex of the patient, were recorded by two observers and analyzed statistically. The branching patterns were initially classified into three types: A, superior type; B, forward type; and C, plexus type. During the investigation, an additional type was found in the premolar area and was classified as type D, an anterior extension type. RESULTS: In total, 243 mandibular sites in 176 subjects were included. Among them, 106 sites displayed branches (43.62%). In the premolar area, most branches were of the anterior extension type (D, 33%), followed by the superior and plexus types (A and C, respectively, 29%), and the forward type (B, 9%). In the molar area, the plexus type was the most common finding (C, 39%), followed by the superior type (A, 32%) and the forward type (B, 29%). Branches in the molar area were significantly more frequent in men than in women (P = .011). CONCLUSION: IAC branches with four branching patterns in the premolar and molar areas are not rare and could be detected by CBCT. Clinicians should be aware of these branches during surgical procedures concerning the posterior mandible.

The retromolar canal and its variations: Classification using cone beam computed tomography.

OBJECTIVE: To determine the prevalence of the retromolar canal and its various patterns using cone beam computed tomography (CBCT). METHOD AND MATERIALS: CBCT images with the presence of mandibular third molars from August 2013 to May 2015 were retrospectively investigated. The presence of retromolar canal, its patterns, sides, as well as gender were evaluated by two observers. The pattern of retromolar canal was initially classified into three types: Type A, superior type; Type B, radicular-retromolar type; and Type C, dental type. During the investigation, two additional types were found and further classified: Type D, plexus type; and Type E, forward type. The distribution of retromolar canals between genders and sides was statistically analyzed with Pearson's chi-square test. RESULTS: A total of 201 mandibular sites in 156 subjects (99 women, 57 men) were included. Among them, 128 sites had retromolar canals (63.68%). The presence of retromolar canal was not statistically related to gender or side. Most of the retromolar canals were the radicular-retromolar type (Type B, 38.10%), followed by the superior type (Type A, 29.93%), dental type (Type C, 19.73%), plexus type (Type D, 6.80%), and forward type (Type E, 5.44%). CONCLUSION: There was a high frequency of retromolar canals and these could be classified into five patterns. The clinician should be aware of this anatomical structure when performing surgical procedures involving the retromolar area.

Accuracy of linear measurements using cone beam computed tomography and panoramic radiography in dental implant treatment planning.

PURPOSE: The aim of this study was to investigate the accuracy of linear measurements from cone beam computed tomography (CBCT) images and digital panoramic radiographs at various implant sites. MATERIALS AND METHODS: Fifty implant sites from six skulls were marked with gutta-percha and subjected to CBCT with five different voxel protocols: 0.125 mm, 0.160 mm, and 0.250 mm with the 3D Accuitomo 170 CBCT machine and 0.200 mm and 0.300 mm with the CS 9500 CBCT machine. Images were also taken with the CS 9000 panoramic machine with three protocols: normal head, chin-up, and chin-down positions. Electronic linear measurement of bone height using the corresponding machine's software was recorded by two observers. Physical measurement using a digital caliper with ± 0.02-mm accuracy was directly recorded at the corresponding regions as the gold standard. All image measurements were compared with the physical measurements. The paired sample correlations for physical measurement, mean difference, standard deviation, absolute error, absolute percentage error, and inter- and intraobserver reliability were calculated. RESULTS: Intraobserver and interobserver reliability was more than 0.99. Paired sample correlation between all image measurements and physical measurements was considered statistically significant at P < .05. All image measurements were underestimated by less than 2 mm, except for the chin-down position of the maxilla in the panoramic radiograph. The absolute error and absolute percentage error in the mandible were less than those in the maxilla, and values obtained with CBCT were less than those from panoramic radiographs. CONCLUSION: CBCT images using the 3D Accuitomo 170 and CS 9500 machines and digital panoramic radiographs via a picture archiving and communication system are sufficiently accurate for vertical linear measurements in dental implant treatment planning.