Positioning errors of dental implants and their associations with adjacent structures and anatomical variations: A CBCT-based study

Investigating the effect of thyroid shields and lead glasses on image quality and artefacts in cone beam computed tomography devices: A phantom study

INTRODUCTION

The objective of this study is to investigate and compare the impact of thyroid shields and lead glasses on the image quality (IQ) and artefacts in dental Cone Beam CT (CBCT) images. The current study aims to evaluate the effectiveness of this protective equipment in enhancing the quality of dental CBCT images.

METHODS

In this study, a New Tom dental CBCT device was used to scan Pro-Project phantom with and without thyroid shields and lead glasses in three different large, medium, and small Fields of View (FOVs). The several key IQ parameters such as noise, contrast-to-noise ratio (CNR), homogeneity, contrast-resolution (CR), and spatial-resolution (SR), were evaluated using ImageJ software. The measurements were performed and compared in various cross-sections based on the location of test objects in the phantom.

RESULTS

The study found that the use of thyroid shields and lead glasses resulted in a decrease in CNR and homogeneity parameters, while noise increased. However, there were no significant changes in SR and CR. It should be noted that the use of thyroid shields and lead glasses may increase image noise by 1-7 %. The combined use of lead shields was not included in our findings, as their effects are localized and similar to separate evaluations in adjacent areas in lower and upper sections.

CONCLUSION

Thyroid shields and lead glasses during dental CBCT imaging increase image noise and reduce CNR. Proper placement is crucial, and reducing the FOV size can minimise artefacts while preserving diagnostic accuracy.

IMPLICATIONS FOR PRACTICE

Thyroid shields and lead glasses are vital for radiation protection. Increased noise demands attention in clinical practice. Ongoing research, training, quality assurance, and effective patient communication are essential for safety and trust in dental imaging.

Prevalence of Dental Implant Positioning Errors: A Radiographic Analysis

Objectives Implant placement errors remain a persistent challenge, leading to complications such as peri-implant bone loss, neurosensory issues, and, in severe cases, implant failure. This study evaluates the prevalence and characteristics of dental implant positioning errors in patients treated at the Dental University Hospital. Methods: A sample of 500 cone-beam computed tomography (CBCT) scans was used to assess implants for positioning errors, including thread exposure, proximity to anatomical structures, and violations of inter-implant and implant-tooth distances. Results: A total of 56.6% of the implants exhibited positioning errors, with the maxillary posterior region being the most commonly affected area (51.6%). The most frequent errors observed were thread exposure (37.7%) and implant proximity to the maxillary sinus (27.7%). Statistical analysis revealed significant correlations between implant positioning errors and anatomical location, underscoring the need for meticulous preoperative planning and advanced imaging. While factors such as patient age, implant length, and diameter were analyzed, no statistically significant differences were found in error prevalence based on sex or demographic variables. Conclusions: This study highlights the importance of combining clinical expertise with advanced imaging modalities like CBCT to minimize implant positioning errors and improve patient outcomes. Future research should focus on refining surgical techniques and evaluating the impact of the implants' design and patient-specific factors on the accuracy of placements.

Incidental Findings Following Dental Implant Procedures in the Mandible: A New Post-Processing CBCT Software Analysis

Background/Objectives: The aim of this study was to evaluate incidental findings in the mandible after the placement of dental implants using a new cone-beam computed tomography (CBCT) software. Methods: The initial sample consisted of 2872 CBCT scans of patients of both sexes. The parameters evaluated in this study were the location of the implants in the mandible, implant length, anatomical relationship of the implant with the mandibular canal, presence or absence of damage to the adjacent teeth, presence or absence of implant fractures, and presence or absence of bone support. Fisher's exact test was performed to compare the variables. The significance level was set at p = 0.05. Results: Out of 2872 CBCT scans, 214 images of patients with an average age of 44.5 years were included. The most frequent location of the implants was the posterior region (93.5%), with 54% of the implants having a length between 9 and 14 mm. It was found that 92% of the implants were positioned above the mandibular canal. Damage to adjacent teeth was observed, with no correlation with the implant positioning (p = 1.000). In 100% of cases of implants in the anterior region, there was bone support. Fracture was observed in 1.7% of implants with a length between 9 and 14 mm. Conclusions: The installation of implants in the mandible occurs more frequently in the posterior region, with a high presence of bone support and a low incidence of damage to adjacent teeth, anatomical structures, and fractures.

Retrospective evaluation and descriptive analysis of the prevalence of anatomical structures and variations in CBCT images before dental implant planning in a group Turkish population, part I

PURPOSE

The aim of this study is to emphasize the importance of using cone-beam computed-tomography in order to determine the anatomical structures and their variations before the treatment in patients who apply to the dentist clinic for implant treatment.

METHODS

In the study, CBCT images of 500 adult patients (240 female and 260 male), aged between 21 and 82 years, who applied for implant treatment due to missing teeth, were retrospectively analyzed. Anatomical structures and variations such as nasopalatine canal(NPC), canalis sinuosus(CS), antral alveolar artery(AAA), were evaluated in multiplanar reformation(MPR) sections which are axial, sagittal and coronal can be viewed in consistence with each other.

RESULTS

The incidence of anatomical variation of CS in the right region was similar according to gender. The "Funnel" appearance of the NPC shape was found most common shape in both female and male patients (n = 89; 37.1% for females and n = 71; 27.3% for males).

CONCLUSION

CBCT has become the most popular 3D imaging method in dental practice especially for planning dental implants. Understanding the relationship with important anatomical structures before implant applications is crucial in dealing with potential complications that may arise afterward. Assessing significant anatomical structures by CBCT and taking precautions against possible risks facilitate the work of dentists during and after procedures.

Association between maxillary sinus floor perforation by dental implants and mucosal thickening: A cone-beam computed tomography study

OBJECTIVE

To investigate the association of perforation of the maxillary sinus floor by dental implants with mucosal thickening and to describe its characteristics in perforated cases.

STUDY DESIGN

One-hundred and twenty-nine maxillary sinuses of 93 patients presenting 202 dental implants in the maxillary posterior region were retrospectively assessed in cone-beam computed tomography scans and classified according to maxillary sinus perforation, bone graft, mucosal thickening, and mucosal appearance. Logistic regression determined the chance of mucosal thickening in perforated maxillary sinuses. The chi-square test compared categorical variables between maxillary sinus perforated or not by implants and maxillary sinus with or without mucosal thickening. The significance level assumed was 5 % (α = 0.05).

RESULTS

There was perforation of 60 maxillary sinuses floor (46.5 %) by 74 dental implants. The chance of mucosal thickening was higher when the implant tip was trespassing on the maxillary sinus floor (p < 0.001). There was a significant association between maxillary sinus mucosal thickening and perforation by a dental implant with the tip trespassing the maxillary sinus floor (p < 0.05).

CONCLUSION

Maxillary sinus mucosal thickening is associated with sinus floor perforation by dental implants and does not depend on the number of implants perforating it.

CLINICAL RELEVANCE

There is an association between dental implants' perforation of the maxillary sinus floor and the thickening of the maxillary sinus. In those cases, the appearance of the mucosa thickening may be irregular, local, or total opacification of the sinus cavity.

Prevalence of dental implant positioning errors: A cross-sectional study

Purpose

This study evaluated the prevalence of dental implant positioning errors and the most frequently affected oral regions.

Materials and Methods

A sample was obtained of CBCT images of 590 dental implants from 230 individuals who underwent diagnosis at a radiology center using cone-beam computed tomography from 2017 to 2020. The following variables were considered: thread exposure, violation of the minimum distance between 2 adjacent implants and between the implant and tooth, and implant contact with anatomical structures. Descriptive data analysis and the Pearson chi-square test (P<0.05) were performed to compare findings according to mouth regions.

Results

Most (74.4%) of the 590 implants were poorly positioned, with the posterior region of the maxilla being the region most frequently affected by errors. Among the variables analyzed, the most prevalent was thread exposure (54.7%), followed by implant contact with anatomical structures, violation of the recommended distance between 2 implants and violation of the recommended distance between the implant and teeth. Thread exposure was significantly associated with the anterior region of the mandible (P<0.05). The anterior region of the maxilla was associated with violation of the recommended tooth-implant distance (P<0.05) and the recommended distance between 2 adjacent implants (P<0.05). Implant contact with anatomical structures was significantly more likely to occur in the posterior region of the maxilla (P<0.05).

Conclusion

Many implants were poorly positioned in the posterior region of the maxilla. Thread exposure was particularly frequent and was significantly associated with the anterior region of the mandible.

Screw-and-cement–retained prosthesis versus cement-retained prosthesis: Which is more appropriate for the upper premolar area?

Background/purpose

The narrow alveolar ridge in the maxillary premolars area limits the angle of implant placement and the shape of the prosthesis. The aim of this study was to evaluate which implant prosthesis, screw-and-cement-retained prosthesis (SCRP) or cement-retained prosthesis (CRP), was more suitable for the maxillary premolar area.

Materials and methods

We conducted virtual implantation on 58 implant images from 47 patients obtained using cone beam computed tomography (CBCT). The width and buccal inclination of the alveolar bone, the angulation of the implant fixture, and the angulation of abutment were measured and calculated.

Results

We determined that SCRP was feasible in 52% and 78.8% of first and second premolar areas, respectively. There was a positive relationship between the feasibility of SCRP and the premolar region in general (P = 0.031), although SCRP was more likely to be a possibility in the second premolar area. On multiple logistic regression analysis, the difference in the angle between the axis of the prosthesis and the axis of the alveolar bone (RA) was significantly associated with the type of prosthesis (P = 0.001). The RA was significantly higher for CRP implants (OR = 1.885; 95% CI: 1.31 to 2.70).

Conclusion

SCRP is not always feasible in the maxillary premolar area, especially in the first premolar area. If the difference between the angle of the axis of the prosthesis and the axis of the alveolar bone is large, it may be necessary for the clinician to consider CRP in the treatment planning stage.

Examination of Canalis Sinuosus using Cone Beam Computed Tomography in an Australian Population

BACKGROUND

Canalis sinuosus (CS) and its relationship with adjacent teeth is relevant for surgery in the anterior maxilla. Therefore, the aim of this study was to report the prevalence, characteristics, and variations of CS.

METHODS

Cone beam computed tomography (CBCT) scans of the anterior maxilla of 201 patients were reviewed. CS and the adjacent teeth were analysed by age, sex, and scan resolution, using analysis of variance, chi-squared and Fisher's exact tests. The widest and narrowest diameters of CS, and distance to tooth apex (DTA), were compared by quadrant, closest tooth, and location, and the associations were examined statistically with P < 0.05.

RESULTS

In the 201 scans, 412 CS were identified in 198 patients associated with 395 different teeth. Mean widest diameter was 1.08 ± 0.39 mm (range: 0.42-2.60 mm), while the narrowest diameter was 0.71 ± 0.26 mm (range: 0.25-1.59 mm), and mean DTA of 2.16 ±1.25 mm (range: 0-6.22 mm). CS detection was significantly lower with CBCT taken at resolution size of 0.250 voxels (P = 0.02).

CONCLUSIONS

CS was very common in the anterior maxilla. Clinicians would be well advised to identify this anatomical structure using CBCT before undertaking any surgery in the anterior maxilla. © 2022 Australian Dental Association.

The occurrence of dental implant malpositioning and related factors: A cross-sectional cone-beam computed tomography survey

Purpose

Dental implants are widely used for the rehabilitation of edentulous sites. This study investigated the occurrence of dental implant malpositioning as shown on post-implantation cone-beam computed tomography (CBCT) and to identify related factors.

Materials and Methods

Samples with at least 1 malpositioned dental implant were collected from a central radiology clinic in Tehran, Iran from January 2017 to January 2019. Variables such as demographic characteristics, length and diameter of implants, type of implant, sites of implant insertion, different types of implant malpositioning problems (cortical plate perforation, interference with anatomical structures), angulation of the implant, and the severity of malpositioning were assessed. In addition, the incidence of implant fracture and over-drilling was evaluated. Data were statistically analyzed using the chi-square test, 1-sample t-test, and Spearman correlation coefficients.

Results

In total, 252 patients referred for implant postoperative CBCT evaluations were assessed. The cases of implant malpositioning included perforation of the buccal cortical plate (19.4%), perforation of the lingual cortical plate (14.3%), implant proximity to an adjacent implant (19.0%), implant proximity to an adjacent tooth (3.2%), interference with anatomical structures (maxillary sinus: 18.3%, mandibular canal: 11.1%, nasal cavity: 6.3%, mental foramen: 5.6%, and incisive canal: 0.4%). Implant fracture and over-drilling were found in 1.6% and 0.8% of cases, respectively. Severity was categorized as mild (9.5%), moderate (35.7%), severe (37.7%), and extreme (17.1%), and 52.4% of implants had inappropriate angulation.

Conclusion

CBCT imaging is recommended for detecting dental implant malpositioning. The most common and severe type of malpositioning was buccal cortex perforation.

Long term clinical result of implant induced injury on the adjacent tooth

The purpose of the retrospective study was to investigate the long-term result of implant-induced injury on the adjacent tooth. The subjects of this retrospective study were patients who had received implants and had tooth injury; direct invasion of root (group I), root surface contact (group II), or < 1 mm distance of the implant from the root (group III). Clinical and pathological changes were periodically examined using radiographs and intra-oral examinations. Paired t-tests and chi-square tests were used to evaluate the implant stability quotient (ISQ) of implant and tooth complications, respectively (α = 0.05). A total of 32 implants and teeth in 28 patients were observed for average 122.7 (± 31.7, minimum 86) months. Seven teeth, three of which were subsequently extracted, needed root canal treatment. Finally, 90.6% of the injured teeth remained functional. Complications were significant and varied according to the group, with group I showing higher events than the others. The ISQs increased significantly. One implant in group I resulted in osseointegration failure. The implant survival rate was 96.9%. In conclusion, it was found even when a tooth is injured by an implant, immediate extraction is unnecessary, and the osseointegration of the invading implant is also predictable.