Three-dimensional alveolar bone assessment of mandibular molars for immediate implant placement: a virtual implant placement study

High-Precision Implant Cavity Fabrication Using Femtosecond Lasers

Objective: This study aims to enhance the precision of implant cavity preparation, addressing a notable challenge in the current state of the field by utilizing femtosecond lasers. Background: The application of femtosecond lasers in implant cavity preparation heralds a noninvasive and efficient technique, characterized by diminished thermal damage and high biocompatibility. Despite these promising attributes, the realization of precise cavity preparation remains a significant challenge in the contemporary domain. Materials and Methods: Our research group devised a specialized femtosecond laser microsurgery robotic system tailored for sophisticated implant cavity preparation. This system facilitated the meticulous analysis of sheep shank bone samples, enabling precise three-dimensional cutting. The analysis included an extensive examination of ablation effects, using a laser scanning microscope and VK Analyzer software. This investigation spanned the phases of laser flux calibration and experimental validation, offering a critical evaluation of the automated preparation process. Results: The study delineated that at the focus position of our custom-made oral clinical femtosecond laser microsurgery robotic system, the laser spot diameter is 75.69 μm, and ascertained the ablation threshold for sheep shank cortical bone to be 1.47 J/cm2. Utilizing low laser flux with minimal ablation craters overlap compromised the sidewall precision of the implant cavity, whereas employing high laser flux with extensive ablation craters overlap resulted in an enlarged ablation angle. At a laser energy setting of 2.2362 J/cm2 and a 50% ablation crater overlap, an implant cavity was successfully crafted featuring a top diameter of 4.41 mm, a bottom diameter of 3.98 mm, and a depth of 3 mm, devoid of any adverse thermal effects such as cracking or carbonization. Conclusions: The oral clinical femtosecond laser microsurgery robotic system can achieve automated and precise implant cavity preparation. This advancement promotes the broader application of femtosecond lasers in the field of orthopedics.

Risk Assessment of Nasal Cavity Perforation in the Maxilla: A Virtual Implant Placement Study Using Cone Beam Computed Tomography

Implant surgery in individuals with atrophic maxilla presents challenges, particularly concerning nasal cavity complications such as perforations, implant migration, and airway obstruction. While panoramic radiographs offer diagnostic convenience, their two-dimensional nature limits the evaluation of anatomical structures. Cone beam computed tomography (CBCT) provides a three-dimensional assessment, enhancing surgical planning accuracy and potentially reducing complications. With the aim of understanding the measurement differences between panoramic radiographs and CBCT images, this retrospective study examined CBCT images of patients with severely atrophic maxilla taken between September 2021 and December 2023 at the Ahmet Keleşoğlu Faculty of Dentistry. Virtual implants were placed in various tooth regions using OnDemand3D software. The incidence of nasal cavity perforations and vertical bone height differences between panoramic radiographs and CBCT images were evaluated. For this purpose, vertical bone length measurements in panoramic and CBCT images were compared for the virtual implant placement areas. Statistical analyses, including t-tests and ANOVA, were performed to determine significant differences among quantitative measurements, and a chi square test with Bonferroni corrected z-tests were used for possible associations between ratios. CBCT data from 59 patients, totaling 1888 virtual implants, revealed significant differences in implant depths among tooth regions (F = 9.880, p < 0.001). Canine regions showed higher perforation risks, especially with 12 mm and 14 mm implants. Panoramic radiographs often overestimated vertical bone height in canine and first premolar regions compared to CBCT measurements, which could lead to increased perforation risks. Radiographic evaluations using CBCT prior to implant surgery in atrophic maxilla cases are crucial to prevent nasal cavity complications. Panoramic radiographs may inadequately represent three-dimensional anatomy, underscoring the importance of CBCT for accurate implant placement and surgical planning. Further studies should consider varying implant sizes and brands to generalize findings.

Three-dimensional radiographic assessment of immediate implant placement in the posterior mandible: A novel parameter-based classification

OBJECTIVES

To assess the implant position (IP), the interradicular septum width (ISW) and radiographic bone to implant contact (BIC), when simulating an immediate implant placement in first and second mandibular molars.

STUDY DESIGN

75 patients (150 sites) were studied using cone beam computed tomography scans (CBCT) and computer aided design software. Implants were placed in a prosthetically driven position; subsequently, IP and BIC were digitally calculated. Linear ISW was also analyzed at 2, 4 and 6mm apically to the highest septal bony peak. Multiple linear regressions were performed to assess relationships between BIC and the different predictive variables. Additionally, the receiver operating characteristics (ROC) curve was used to create a model for BIC based on the ISW at 2mm.

RESULTS

BIC in implants replacing first molars was the highest at the septal (S) position when compared to those in septal-mesial (S-M) position (p-value 0.001). As for the second molar, the highest percentage of BIC was recorded at the septal (S) position, followed by those in S-M and mesial (M) positions (p<0.001).

CONCLUSION

According to the proposed classification, clinician must consider the ISW and IP when placing immediate implant in the first and second mandibular molar sites. When tackling first molars, S position is predominant, while S-M position is the most common in the second molars. ISW at 2mm should be at least respectively 2mm and 2.5mm at the first and second molar sites to achieve 50% of BIC.

Five-year outcomes of immediate implant placement for mandibular molars with and without chronic apical periodontitis: A retrospective study

BACKGROUND

Most physicians consider molars with chronic apical periodontitis (CAP) lesions as contraindications for immediate implant placement. At the patient’s request, we perform immediate implant placement of the mandibular molars with CAP in clinical practice.

AIM

To retrospectively analyze and compare the 5-year outcomes of immediate implant placement of the mandibular molars with CAP and those without obvious inflammation.

METHODS

The clinical data of patients with immediate implant placement of the mandibular molars in the Department of Oral and Maxillofacial Surgery, the Affiliated Hospital of Qingdao University, from June 2015 to June 2017 were collected. The patients were divided into CAP (n = 52) and no-CAP (n = 45) groups. Changes in bone mineral density and bone mass around implants were analyzed 5 years after implant restoration.

RESULTS

At 5 years after implantation, the peri-implant bone mineral density was 528.2 ± 78.8 Hounsfield unit (HU) in the CAP group and 562.6 ± 82.9 HU in the no-CAP group (P = 0.126). Marginal bone resorption around implants did not differ significantly between the two groups, including buccal (P = 0.268) or lingual (P = 0.526) resorption in the vertical direction or buccal (P = 0.428) or lingual (P = 0.560) resorption in the horizontal direction. Changes in the peri-implant jump space did not differ significantly between the two groups, including the buccal (P = 0.247) or lingual (P = 0.604) space in the vertical direction or buccal (P = 0.527) or lingual (P = 0.707) space in the horizontal direction. The gray value of cone-beam computed tomography measured using Image J software can reflect the bone mineral density. In the CAP area, the gray values of the bone tissue immediately and 5 years after implant placement differed significantly from those of the surrounding bone tissue (P < 0.01).

CONCLUSION

The results of this study suggest that immediate implant placement of the mandibular molars with CAP can achieve satisfactory 5-year clinical results, without significant differences in the complications, survival rate, or bone tissue condition from the no-CAP mandibular molars.

Five-year outcomes of immediate implant placement for mandibular molars with and without chronic apical periodontitis: A retrospective study

BACKGROUND

Most physicians consider molars with chronic apical periodontitis (CAP) lesions as contraindications for immediate implant placement. At the patient's request, we perform immediate implant placement of the mandibular molars with CAP in clinical practice.

AIM

To retrospectively analyze and compare the 5-year outcomes of immediate implant placement of the mandibular molars with CAP and those without obvious inflammation.

METHODS

The clinical data of patients with immediate implant placement of the mandibular molars in the Department of Oral and Maxillofacial Surgery, the Affiliated Hospital of Qingdao University, from June 2015 to June 2017 were collected. The patients were divided into CAP (n = 52) and no-CAP (n = 45) groups. Changes in bone mineral density and bone mass around implants were analyzed 5 years after implant restoration.

RESULTS

At 5 years after implantation, the peri-implant bone mineral density was 528.2 ± 78.8 Hounsfield unit (HU) in the CAP group and 562.6 ± 82.9 HU in the no-CAP group (P = 0.126). Marginal bone resorption around implants did not differ significantly between the two groups, including buccal (P = 0.268) or lingual (P = 0.526) resorption in the vertical direction or buccal (P = 0.428) or lingual (P = 0.560) resorption in the horizontal direction. Changes in the peri-implant jump space did not differ significantly between the two groups, including the buccal (P = 0.247) or lingual (P = 0.604) space in the vertical direction or buccal (P = 0.527) or lingual (P = 0.707) space in the horizontal direction. The gray value of cone-beam computed tomography measured using Image J software can reflect the bone mineral density. In the CAP area, the gray values of the bone tissue immediately and 5 years after implant placement differed significantly from those of the surrounding bone tissue (P < 0.01).

CONCLUSION

The results of this study suggest that immediate implant placement of the mandibular molars with CAP can achieve satisfactory 5-year clinical results, without significant differences in the complications, survival rate, or bone tissue condition from the no-CAP mandibular molars.

The clinical effect of the digital guide in the early implant restoration of second molars

BACKGROUND

In the absence of contraindications to implants, implant repair is the preferred method to treat mandibular second molar loss.

OBJECTIVE

To compare the clinical effects of a traditional implant guide and digital implant guide in the early implant restoration of second molars.

METHODS

The study included 35 patients with second molar loss randomly divided into two groups. Eighteen patients in the experimental group had an implant procedure using a computer-aided design/computer-assisted manufacturing (CAD/CAM) digital implant guide, and 17 patients in the control group had the procedure using a traditional film pressing implantation guide. Then, the surgical procedure was completed using the two different implant guides. At 3 months after surgery, four parameters including screw hole exit position, coronal deviation of the implant site, disease improvement rate, and clinical effects, which included marginal adaptation, anatomic form, marginal discoloration, postoperative sensitivity, surface roughness, and secondary caries of the upper prosthesis were compared between the two groups.

RESULTS

The screw hole exit position in the experimental group was directed to the functional cusp of the opposite jaw, and there was a statistically significant difference between the two groups. There was no statistically significant difference in the rate of disease improvement and the clinical effect of the upper prosthesis between the two groups. There was no statistically significant difference in the bilateral coronal deviation and deviation direction of implants in the two groups. The bilateral coronal deviation of the experimental group was smaller than that of the control group.

CONCLUSION

The digital implant guide can effectively reduce the deviation of the screw hole and the upper prosthesis in the restoration of the second molar. The prosthesis used in the experimental group had a good clinical outcome, which provides a theoretical basis for the restoration of the posterior molar.

Relevant factors of posterior mandible lingual plate perforation during immediate implant placement: a virtual implant placement study using CBCT

BACKGROUND

To explore the influence of cross-sectional type and morphological parameters at the mandibular molar sites on lingual plate perforation (LPP) during the immediate implant placement (IIP).

METHODS

181 implants were virtually placed in the mandibular molar sites on the cone beam computed tomography (CBCT). Each cross-section of the implantation site was divided into the Undercut (U)/Parallel (P)/Convex (C) types. Morphologically relevant parameters were measured on the cross-sections, including width of the upper end (Wb), width of the lower end (Wc), vertical height (V), angle between the natural crown axis and the alveolar bone axis (∠β), LC depth (LCD), LC height, and angle between the horizontal line and the line connecting the most prominent point and the most concave point of lingual plate (∠α). Besides, the distance from the end of the virtual implant and the lingual bone plate of the cross-section (D_IL) was calculated. Relationships between all the morphologically relevant parameters and the D_IL were further analyzed.

RESULTS

A total of 77 (42.5%) cross-sections were classified as U-type, which was the most common one, accounting for 63% of the second molar regions. All LPP cases and most of the nearly LPP (87.9%) cases occurred at the U-type cross-sections, and the relationship between the D_IL and the morphological parameters can be expressed by a multivariate linear equation.

CONCLUSIONS

The occurrence rate of U-type cross-sections in the second molar region was very high, and the risk of LPP should be considered during IIP. Except for the U-type, significant large LCD, small Wc, and large ∠β were the important relevant factors. CBCT and multivariate linear equations could help to assess the LPP risk and provide a reference for implant placement design pre-surgery.

Assessment of Maxillary Molars Interradicular Septum Morphological Characteristics as Criteria for Ideal Immediate Implant Placement—The Advantages of Cone Beam Computed Tomography Analysis

The aim of this study was to evaluate the interradicular septum bone morphometric characteristics using cone beam computed tomography (CBCT) images, as well as to establish quantitative shortcuts to allow clinicians to make a faster and more reliable plan for immediate implant placement in the maxillary molars area. This retrospective quantitative study was conducted on CBCT images obtained from 100 patients. The morphometric analysis of the maxillary molars region was based on the parameters obtained on the sagittal and axial slices. The analysis performed on sagittal slices showed that the first maxillary molars had a wider interradicular septum when compared to the second molars, but the septum height in the first molars was significantly below the height in the second maxillary molars. The axial CBCT slices analysis showed that both interradicular septum perimeter and surface area were significantly more pronounced in the first than in the second maxillary molars. The interradicular furcation angle significantly correlated with the surface area (positively) and septum height (negatively) for both molars. The results of this study may recommend CBCT image analysis as a useful tool in predefining the circumstances that can allow for substantially better planning of immediate implant placement procedures in the region of maxillary molars.

Morphological Characteristics of Maxillary Molars Interradicular Septum and Clinical Implications - What do We Know So Far?

The interradicular septum describes area in the root furcation that separate alveoli of multi-rooted teeth. The shape and dimension depend of the topography of the extraction socket, the geometry of residual root and anatomy of molars alveoli. The clinical implications of this anatomic structure may be used in oral surgery resection procedures, periodontology and implantology. There is an opinion from the surgical and prosthodontic side that center of interradicular septum may be adequate place for immediate implantation. The aim of this study was to investigate morphological characteristics and clinical implications of upper molars interradicular septum. The studies showed that interradicular septum is important for success of resection surgery procedures: hemi-section, bisection and root amputation. It’s reported that furcation involvement in periodontal disease is clinical sign for severe bone loss. By reviewing the available literature for immediate implantation, it’s reported the clinical implications for diagnostical plan (pre-intervention), presurgical (pre-instrumentation) and intraoperative evaluation of interradicular septum for immediate implantation. The cone beam computed tomography analyze study presented mean values of septum height and wide for hypothetical plan of immediate implant placement. The presurgical studies evaluate how to assure preservation of septum and safe implant position in center of septum. The research showed varies therapy modalities that can be used, and how to choose right therapy according the socket type and initial septum width classification. According to observation of studies results, other researches should be considered for CBCT anatomical structure analyze and measures of interradicular septum for immediate implantation planning.