Ridge Dimensions of the Edentulous Mandible in Posterior Sextants: An Observational Study on Cone Beam Computed Tomography Radiographs

Correction of Peri-Implant Buccal Bone Dehiscence Following Sub-Periosteal Peri-Implant Augmented Layer Technique With Either Block or Particulate Xenograft: A Retrospective Study

OBJECTIVE

To evaluate the effectiveness of Sub-periosteal Peri-implant Augmented Layer (SPAL) technique performed with deproteinized bovine bone mineral (DBBM), delivered either as particulate (pDBBM) or block (bDBBM), in correcting a peri implant bone dehiscence (PIBD). Implants showing a thick (≥ 2 mm) peri-implant buccal bone plate (PBBP) at placement were also examined.

MATERIAL AND METHODS

Patients with a PIBD ≥ 1 mm, treated with SPAL with either pDBBM (SPALparticulate) or bDBBM (SPALblock), and patients with an implant showing a PBBP ≥ 2 mm at insertion (CONTROL) were included. Re-entry was performed either at 6 months (SPAL groups) or 3 months (CONTROL). The rate of patients presenting no PIBD at re-entry was the primary outcome. Bone dehiscence height (BDH) and width (BDW), thickness of buccal tissues (BTT) and marginal bone level (MBL) were secondary outcomes.

RESULTS

Thirty-nine implants in 39 patients (14 in SPALparticulate,14 in SPALblock and 11 in CONTROL) were analyzed. No PIBD were found in SPALparticulate whereas in SPALblock one PIBD was present. Two patients in CONTROL presented a PIBD. A reduction in both BDH and BDW was observed in both SPALparticulate (2.7 ± 1.6 mm for BDH and 3.9 ± 0.2 mm for BDW) and SPALblock (2.5 ± 1.8 mm for BDH and 3.8 ± 1.1 mm for BDW). SPALblock showed a higher BTT than SPALparticulate at re-entry (3.6 ± 1.3 mm for SPALblock and 2.6 ± 0.6 mm for SPALparticulate, p = 0.0160). All groups showed similar MBL.

CONCLUSION

SPAL performed with either a pDBBM or bDBBM is similarly effective in correcting a PIBD as well as in increasing BTT.

From freehand to precision: Dynamic navigation systems in transmandibular nerve canal implantation: A case series

RATIONALE

This case series explores dynamic navigation systems (DNS) in transmandibular nerve canal implantation for patients with limited jaw space due to the proximity of the inferior alveolar nerve (IAN). The aim is to demonstrate how DNS improves implant placement precision and safety in cases where traditional methods face challenges.

PATIENT CONCERNS

The patients had limited bone height and proximity to the IAN, making traditional implant techniques challenging. Concerns included the risk of nerve damage and difficulties in achieving optimal implant placement due to anatomical constraints.

DIAGNOSES

Both patients had severe bone resorption and insufficient bone height in the posterior mandible, with concerns about IAN positioning. The first patient had grade III mobility in tooth #46 with a periapical infection, while the second had bilateral posterior mandibular pain and grade III mobility in tooth #47.

INTERVENTIONS

Implants were placed using DNS, allowing precise planning and real-time guidance during surgery. Based on cone beam computed tomography, preoperative planning assessed bone height and IAN proximity. DNS ensured accurate implant placement, avoiding nerve interference, while bone grafts and growth factors were applied for healing.

OUTCOMES

Both cases showed successful implant placement without complications like nerve damage or implant misplacement. Follow-up cone beam computed tomography scans confirmed well-positioned implants, with minimal bone resorption in the first case over 2 years and stable conditions in the second case after 6 months.

LESSONS

This series highlights DNS's effectiveness in improving implant accuracy and reducing nerve injury risks, suggesting its value in complex dental implant surgeries.

Correlation between sphenoid sinus pneumatization and sella turcica dimensions using computed tomography

OBJECTIVE

This study was performed to determine the dimensions of the sella turcica (ST) in relation to sex, age groups, and sphenoid sinus (SS) pneumatization patterns in a cohort of Iraqi individuals.

METHODS

This cross-sectional study analyzed computed tomography images of 99 individuals (53 men, 46 women) aged 24 to 59 years to measure ST dimensions, including length, width, height, depth, and surface area. SS pneumatization was classified by sex and age. We also examined the relationship between ST size and SS pneumatization patterns.

RESULTS

Women exhibited a significantly greater mean ST depth (9.37 mm) than men (8.19 mm). The ST diameter was significantly larger in the middle-aged group (13.1 mm) than in the young adult group (11.83 mm). The ST area showed a highly significant difference between sexes. The sellar pneumatization pattern was the most common, whereas the conchal pattern had the lowest prevalence. A significant correlation was observed between ST size and SS pneumatization.

CONCLUSION

The ST depth and diameter showed statistically significant differences across sex and age groups, respectively. The variability in SS pneumatization patterns underscores the importance of considering pneumatization types during surgical planning to minimize the risk of iatrogenic injury and improve treatment outcomes.

Mandibular canal assessment in dentate and edentulous ridges of 400 Iraqi Arab and Kurdish populations using cone beam computed tomography

Objectives

This study aims to compare differences in mandibular canal (MC) location between dentate and edentulous ridges, in the second premolar region as well as the first, second, and third molar regions using cone beam computed tomography (CBCT) of Arabic and Kurdish Iraqi populations.

Materials and Methods

CBCT images of 400 subjects (200 Arabs, 200 Kurds) were collected from radiological archives. RadiAnt DICOM software (Medixant, Poland) was used for image analyses. Measurements were performed from MC to buccal and lingual alveolar crests and to buccal, lingual, and inferior aspect of the mandible for both dentate and edentulous ridges. Additionally, distance to the most superior aspect of residual edentulous ridge were performed. Independent t-test and Mann-Whitney U Test were performed utilising SPSS v.26.

Results

Distances from MC to buccal and lingual alveolar crests were consistently lower in edentulous ridge compared to dentate ridge across all teeth regions. Distances to lingual and inferior border of the mandible were higher in edentulous ridge compared to dentate ridge of all teeth regions. Distances to buccal surface of the mandible varies with fluctuations of dentate and edentulous ridges displaying higher measurements. Distance to superior aspect of residual edentulous ridge revealed mean values in the range of 13.45 to 15.69 mm in Arabs and 13.96 to 16.37 mm in Kurds.

Conclusions

Discrepancy in vertical position of MC was observed between dentate and edentulous ridges within Arab and Kurd populations. Horizontal position of MC was unaffected by tooth loss and found to be closer to lingual surface of all molars. The residual alveolar ridge was sufficient to accommodate the common length and width of dental implants.

Clinical significance

The findings could play a crucial role in planning surgical interventions of the mandible, helping to prevent complications that might arise due to inadequate preoperative assessments.

Feasibility of implant placement in healed mandibular molar sites: A retrospective cone beam computed tomography study

STATEMENT OF PROBLEM

Implant placement in the mandibular molar sites plays a crucial role in the restoration of edentulous mandibles. However, the evaluation of bone quantity before implant surgery using cone beam computed tomography (CBCT) is lacking.

PURPOSE

The purpose of this clinical study was to evaluate CBCT images of edentulous patients to analyze the feasibility of implant placement in healed mandibular molar sites.

MATERIAL AND METHODS

The CBCT data of 138 patients were analyzed in the sagittal plane for measurements of mandibular bone height (MBH), superior bone height (SBH), inferior bone height (IBH), buccal bone width (BBW), lingual bone width (LBW), and alveolar bone widths (ABWs). The edentulous sites were categorized according to the bone quantity and complexity of the implant surgery. Multivariate analysis of variance (MANOVA) was used to analyze the site, sex, and age-related variations. An independent t test was used to compare the difference of bone dimension in different sites and between sexes. One-way ANOVA followed by post hoc tests were used to analyze the difference between different age groups. Categorical variables were presented as number of events and percentages. The chi-squared test was used to compare categorical variables (α=.05).

RESULTS

A total of 534 sites of interest were recorded, including 274 hemimandibles. A significant difference in BBW was found between the first and second molar sites. Men had higher MBH, SBH, IBH, and BBW than women. The distribution of implant surgical complexity in the conventional group was 63.5%, while the buccolingual tilted implant group accounted for 17.0%, and the complicated group accounted for 19.5%. Of the 274 hemimandibles, an implant could be placed directly at molar sites in 88% of situations.

CONCLUSIONS

The BBW at the mandibular second molar site was greater than that at the first molar site. The amount of available bone in the SBH and BBW was greater in men than in women at the healed molar sites. Age did not significantly affect the complexity of the implant surgery. Implants can be placed directly in healed mandibular molar sites in most patients who require a complete arch mandibular implant-supported restoration.

Effect of lateral bone augmentation procedures in correcting peri-implant bone dehiscence and fenestration defects: A systematic review and network meta-analysis

Purpose

The aim of the present systematic review was to evaluate the effect of different lateral bone augmentation (LBA) procedures on the complete correction of a peri‐implant bone dehiscence (BD) or fenestration (BF) from implant placement to implant surgical uncovering.

Methods

Electronic (Medline, Scopus, and Cochrane databases) and hand literature searches were performed for studies including at least one treatment arm where any LBA had been applied to correct a BD/BF at implant placement (T0). Studies where BD/BF was left untreated were also retrieved as negative control. Data from 24 selected articles were used to perform a network meta‐analysis. Based on the proportion of nonresolved BD/BF at implant surgical uncovering (T1), a hierarchy of LBA procedures, and was determined. Spontaneous healing (i.e., exposed implant surface covered by a full‐thickness flap; SELF) was also included in the hierarchy. Resorbable membrane + bone graft (RM + BG) was used as reference group. An analysis on the effect of nonhuman (NHBS) vs human (HBS) derived bone substitutes was also performed. NHBS was used as the reference group.

Results

No statistically significant differences were found among treatments for the proportion of nonresolved BD/BF. SELF performed substantially worse compared to RM + BG (OR: 5.78 × 10, CI: 4.83 × 10 – 1.3 × 10⁸⁶). Treatment based on a combination of a graft material and membrane/periosteum appeared to perform slightly better than treatments using graft material or membrane alone. NHBS appeared to perform better than HBS.

SELF had the worst effect among all treatments for both BD/BF height reduction (BDH) and BD/BF width reduction (BDW). Nonresorbable membrane (NRM) and patient's own periosteum (PERI) + BG showed greater increases in buccal bone thickness than RM + BG.

Conclusion

Reconstructive treatment (including use of graft alone, membrane alone, or combinations of grafts and either membrane or patient's own periosteum) of a BD/BF at implant placement favorably and significantly impacts on the probability to obtain complete correction of the BD/BF at implant uncovering when compared to full‐thickness flap repositioning on the BD/BF. When using a bone substitute, a nonhuman derived one may be suggested.

Quantitative assessment of the jawbone quality classification: A meta-analysis study

AIM

Bone quality is evaluated using bone density for qualitative classification, a characteristic that may be delicate to evaluate. Contemporary implantology that relies on modern measurement techniques, needs a more quantitative estimate of the bone quality.

MATERIALS AND METHODS

PubMed and EMBASE databases were searched with no time restriction. Clinical and radiographic studies reporting on alveolar ridge dimensions and its parameters in different areas of the dentate and edentulous jaws were included. A meta-analysis was performed using random effect models to report a combined mean for alveolar ridge and its parameters. Meta regression statistical tests were performed in order to identify differences in those outcome parameters.

RESULTS

30 studies were included. The majority of the selected studies (total of 27) used live human subjects and CBCT to analyze alveolar ridge dimensions and its parameters. Using the combined mean obtained from the meta-analysis, a typical portrait of the alveolar ridge was constructed, and a geometrically based quantitative bone classification proposed. The quantitative classification was found to match the existing qualitative classification.

CONCLUSION

A geometry-based analysis was constructed that yields valuable insights on the bone type based on its components and on the dynamics of the dentate / edentulous states.

Mandibular residual ridge morphology in relation to complete dentures and implant overdentures-Part I: Predictors for perceived conventional denture stability

BACKGROUND

There is lack of reliable predictors for success of conventional complete denture (CCD) therapy, which in turn might affect the effectiveness of subsequent implant-retained overdenture (IOD) therapy.

PURPOSE

To investigate relationships between digitally obtained geometrical mandibular residual ridge measures and perceived CCD-stability.

MATERIALS AND METHODS

30 CCD wearing patients (67.9 ± 7.0 years) for whom a new set of CCDs was advised, were treated with new CCDs. Digitalized mandibular gypsum models were measured using the Geomagic Studio 2013 software. Data were obtained for (1) height, width, and cross-section surface area of the residual ridge at different locations (midline, premolar, and anterior edge of retromolar pad) and (2) denture base surface area. Scatter plots and multivariate regression analyses were used to investigate associations between the geometric data and denture base surface area, and correlated with denture stability scores (Spearman rank test).

RESULTS

Scatter plots showed that best model fit for denture base surface area was mean ridge height (R² = 0.906). Multivariate regression showed that height at premolar location (p = 0.001) had largest effect on denture base surface area (R² = 0.796). Ridge morphology variables, except width at midline location, were significantly correlated with CCD-stability (p-values <0.05). CCD-stability was significantly correlated with denture base surface area (p ≤ 0.001).

CONCLUSION

Residual ridge height at premolar location was most predictive for denture base surface area and perceived CCD-stability.

CT-based dentulous mandibular alveolar ridge measurements as predictors of crown-to-implant ratio for short and extra short dental implants

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. Hence, vertical and horizontal dimensions of dentulous posterior mandibles in a sample of 18- to 25-year-olds were measured, and correlations of these dimensions with sex and site were investigated. Mandibular computed tomography scans from 100 subjects were considered. Vertical and horizontal bone and tooth measurements were taken at the sites of the second premolar (PM), and the mesial and distal roots of the first and second molars (M1m, M1d, M2m and M2d, respectively). A hypothetical crown-to-implant ratio (C/I R) was calculated assuming the insertion of short and extra short implants (5, 6 or 7 mm), at 1.5 mm from the inferior alveolar canal, maintaining the position of the existing occlusal plane. All vertical bone dimensions decreased from the PM to the M2d. Width measurements increased from the mesial (PM) to the distal sites (M1m, M1d, M2m and M2d). Males had significantly greater vertical and horizontal measurements than females at all sites. The mean C/I R was higher than 2 for all sizes of implant. The C/I R was lower for the second molar than for the second premolar, while it was similar for the first molar and the second premolar. Males had a higher C/I R than females. Computed tomography can be used to study the anatomical features of alveolar bone, and to predict some clinical aspects of prosthetic rehabilitation with implants, such as the crown-to-implant ratio in conditions of serious bone atrophy.

Contour Changes Following Immediate Placement of Ultra-Wide Implants in Molar Extraction Sockets without Bone Grafting

The aim was to evaluate ridge reduction and mucosal recession following immediate placement of ultra-wide implants in molar sockets, without bone grafting. Impressions were taken prior to tooth extraction, 4 months and 1 year after implant placement. The casts were digitized and compared. Mucosal recessions and horizontal ridge reduction were measured. A total of 16 implants were in the maxilla and 11 in the mandible. At the buccal aspect, there was a mean reduction of 0.94 mm after 4 months and 0.89 mm after one year (p = 0.933). At the palatal/lingual aspect, this was 1.09 mm after 4 months and 0.69 mm after 1 year (p = 0.001). After 1 year, a recession of 0.59 mm was measured at the zenith, 1.04 mm at the mesial and 0.98 mm at the distal papilla. The mean midfacial horizontal ridge reduction was 1.23 mm after 4 months and 1.45 mm after 1 year. At the midpalatal/midlingual aspect, the mean horizontal reduction was 1.43 mm after 4 months and 1.16 mm after 1 year. Immediate implant placement without bone grafting in the posterior jaw yields a significant horizontal ridge reduction and minor mucosal recession. Clinicians should anticipate the amount of ridge reduction and consider augmentation at the time of implant placement.

Denture-reversing technique for assessing the soft tissue dimensional changes according to artificial tooth position in completely edentulous patients

A digital workflow to assess the soft tissue dimensional changes in completely edentulous patients is described. Diagnostic casts obtained at 2 time points and the complete denture were scanned by using a desktop scanner. The denture scan was inverted by using a metrology software program to obtain the soft tissue contour. Using this reversed file as a reference, the file and 2 scan files obtained at different time points were aligned individually with the best fit alignment function. The scanned denture file and the 2 realigned scan files were imported into the same software. A plane vertical to the occlusal plane was determined such that it moved anteroposteriorly. The distance between the contours of the 2 realigned files was measured by selecting a point and a vector based on the artificial tooth positions of the denture. This technique of using a reversed denture file may provide a quantitative evaluation of soft tissue changes and further aid in determining appropriate intervals for denture relining or rebasing.