Smoking may affect the alveolar process dimensions and radiographic bone density in maxillary extraction sites: a prospective study in humans

Intraoral ultrasonography image registration for evaluation of partial edentulous ridge: A methodology and validation study

OBJECTIVES

Ultrasound (US) reveals details for diagnosing soft- and hard-tissue dimensions around teeth, implants, and the edentulous ridge, not seen in 2D radiographs. Co-registering free-hand US scans with other 3D modalities presents reliability challenges. This study first aims to develop and validate a registration method to longitudinally reproduce US images of the jawbone on a simulator. In addition, it also evaluates the degree of the anatomical match in humans between US images acquired by the proposed registration method and the commonly used freehand acquisitions in comparison to cone beam computed tomography (CBCT) and intra-oral optical scan (IOS), used as references.

METHODS

A previously introduced ultrasound phantom was employed as a CBCT-US hybrid, suitable for training and technique development of US guides in edentulous ridges. After establishing feasibility in the phantom, the methodology was validated in a cohort of 24 human subjects (26 cases). Soft tissues were delineated on US and IOS, and hard tissues on US and CBCT. US accuracy and repeatability from both guided and freehand scans (non-guided) was assessed as the average distance between US and the references.

RESULTS

Guided US images resembled the references more closely than freehand (non-guided) scans. Notably, delineation of soft and hard tissues was significantly more accurate when employing guides. In the phantom, guided scans exhibited an absolute mean deviation of 81.8 µm for gingiva and 90.4 µm for bone, whereas non-guided scans showed deviations of 150.4 µm and 177.2 µm, respectively. Similarly, in vivo, guided US outperformed non-guided US, with gingiva deviations of 125 µm and 196 µm, and bone deviations of 354 µm and 554 µm, respectively.

CONCLUSIONS

By using a registration method, guided US scans improved repeatability and accuracy of mapping hard and soft tissue of the edentulous ridge when compared to non-guided scans.

CLINICAL RELEVANCE

This guided US imaging method could lay the foundation for longitudinal evaluation of tissue behavior and dimensional changes with improved accuracy.

Healing of Extraction Sites after Alveolar Ridge Preservation Using Advanced Platelet-Rich Fibrin: A Retrospective Study

BACKGROUND

Over time, numerous surgical procedures and biomaterials have been proposed for the reconstruction of post-extraction bone defects, each with their advantages and disadvantages. The main objective of this study was to evaluate dimensional changes in the alveolar bone 3 months after tooth extraction, before implant planning, comparing alveolar ridge preservation (ARP) with spontaneous healing.

METHODS

A total of 84 patients with non-restorable molars were included in the study. Forty-two patients received ARP with advanced platelet-rich fibrin (A-PRF) and spontaneous healing was evaluated in these patients. Cone beam computed tomography (CBCT) analysis performed before and after surgical intervention was used to determine the changes in vertical and horizontal bone dimensions produced after tooth extraction.

RESULTS

CBCT measurements showed reduction in both vertical and horizontal alveolar bone size in both groups. For the study group, the alveolar parameters (height, width) were higher compared to the control group. The percentage variations between dimensional differences from the two groups were 38.58% for height, and for width were 36.88% at 0 mm, 35.56% at 3 mm, 36.61% at 5 mm, and 38.73% at 7 mm. The differences were statistically significant (p ˂ 0.0005).

CONCLUSIONS

The results obtained after ARP with A-PRF showed a reduced loss of bone volume compared to spontaneous healing.

Learn, unlearn, and relearn post-extraction alveolar socket healing: Evolving knowledge and practices

OBJECTIVE

This review was to offer a comprehensive analysis of currently available evidence on post-extraction alveolar socket healing, including i) the histological and molecular events during alveolar socket healing, ii) the dimensional ridge alterations after socket healing and controversies relating to sinus pneumatisation, iii) the patient-specific factors, procedural elements, and site-related variables influencing socket healing, iv) techniques and effectiveness of alveolar ridge preservation (ARP) procedure, and v) the philosophies and cost-effectiveness of ARP in clinical practice.

SOURCES AND STUDY SELECTION

To investigate the dimensional profiles of the alveolar ridge following unassisted healing, an overview of systematic reviews was conducted in February 2024 by two independent reviewers. Four electronic databases were searched in Pubmed, Embase, Web of science and Cochrane Library between 2004 and 2024 to identify all relevant systematic reviews on post-extraction healing. A further manual search of reviews was also conducted. The articles were further reviewed in full text for relevance. The AMSTAR-2 appraisal tool was adopted to assess methodological quality. Current research pertaining to other listed objectives was objectively analysed in narration.

DATA

11 out of 459 retrieved studies were selected and ultimately covered in this review on the dimensional changes of alveolar ridge following natural healing: Seven systematic reviews and four systematic reviews with meta-analyses. The methodological quality of all included reviews was critically low.

CONCLUSION

This review thoroughly examines the healing profiles of post-extraction alveolar sockets and highlights the dynamic process with overlapping phases and the inter-individual variability in outcomes. ARP procedure is a potential strategy for facilitating prosthetic site development, while the current evidence is limited. Herein, an individualised and prosthetically driven approach is crucial. Further well sized and designed trials with novel biomaterials need to be undertaken, and the role of artificial intelligence in predicting healing and assisting clinical decision-making could be explored.

CLINICAL SIGNIFICANCE

By advancing our understanding of alveolar socket healing and its management strategies, clinicians can make more informed decisions regarding patient and site level assessment and selection, surgical techniques, and biomaterial choices, ultimately contributing to the enhanced healing process with reduced complications and improved quality of life for patients undergoing tooth extraction and dental implant treatments.

Efficacy of Alveolar Ridge Preservation in Periodontally Compromised Molar Extraction Sites: A Systematic Review and Meta-Analysis

AIM

To investigate the efficacy of alveolar ridge preservation (ARP) in periodontally compromised molar extraction sites.

METHODS

An electronic search was performed on 10th November 2023 across five databases, seeking randomised/non-randomised controlled trials (RCTs/NCTs) that included a minimum follow-up duration of four months. The RoB2 and Robins-I tools assessed the risk of bias for the included studies. Data on alveolar ridge dimensional and volumetric changes, keratinized mucosal width, and need for additional bone augmentation for implant placement were collected. Subsequently, a meta-analysis was carried out to derive the pooled estimates.

RESULTS

Six studies were incorporated in the present review, and a total of 135 molar extraction sockets in 130 subjects were included in the meta-analysis. ARP was undertaken in 68 sites, and 67 sites healed spontaneously. The follow-up time ranged from 4 to 6 months. The meta-analysis of both RCTs and NCTs showed significant differences in mid-buccal ridge width changes at 1 mm level below ridge crest with a mean difference (MD) of 3.80 (95% CI: 1.67-5.94), mid-buccal ridge height changes (MD: 2.18; 95% CI: 1.25-3.12) and volumetric changes (MD: 263.59; 95% CI: 138.44-388.74) in favour of ARP, while the certainty of evidence is graded low to very low. Moreover, ARP appeared to reduce the need for additional sinus and bone augmentation procedures at implant placement with low certainty of evidence.

CONCLUSIONS

Within the limitations of this study, alveolar ridge preservation in periodontally compromised extraction sites may, to some extent, preserve the ridge vertically and horizontally with reference to spontaneous healing. However, it could not eliminate the need for additional augmentation for implant placement. Further, longitudinal studies with large sample sizes and refined protocols are needed.

Is alveolar ridge preservation an overtreatment?

The morphology and dimensions of the postextraction alveolar ridge are important for the surgical and restorative phases of implant treatment. Adequate new bone formation and preservation of alveolar ridge dimensions following extraction will facilitate installation of the implant in a restorative position, while preservation of soft tissue contour and volume is essential for an aesthetic and implant-supported restoration with healthy peri-implant tissues. Alveolar ridge preservation (ARP) refers to any procedure that aims to: (i) limit dimensional changes in the alveolar ridge after extraction facilitating implant placement without additional extensive bone and soft tissue augmentation procedures (ii) promote new bone formation in the healing alveolus, and (iii) promote soft tissue healing at the entrance of the alveolus and preserve the alveolar ridge contour. Although ARP is a clinically validated and safe approach, in certain clinical scenarios, the additional clinical benefit of ARP over unassisted socket healing has been debated and it appears that for some clinicians may represent an overtreatment. The aim of this critical review was to discuss the evidence pertaining to the four key objectives of ARP and to determine where ARP can lead to favorable outcomes when compared to unassisted socket healing.

Current Knowledge on the Healing of the Extraction Socket: A Narrative Review

The concept of extraction socket healing has been severally researched and reported over the years, since tooth extraction remains one of the most common procedures performed in the dental clinic. Understanding this healing process is of utmost importance because the outcome has a direct bearing on future prosthetic rehabilitation and, by extension, on patients' esthetics and masticatory function, among others. This mini review, therefore, summarized the current knowledge on the different stages of socket healing, including the biologic and clinical events that occur following tooth extraction up until the complete closure of the socket. Additionally, the modeling of the alveolar bone/process post extraction, and the resultant dimensional changes that, altogether, shape the bone, were reviewed and documented. The effects of various socket preservation interventions to mitigate these dimensional changes, and therefore preserve the alveolar process in a condition suitable for future prosthetic rehabilitation, were highlighted. Finally, a review of some of the factors that influence the entire process was also carried out.

Tomographic Evaluation of Alveolar Ridge Preservation Using Bone Substitutes and Collagen Membranes—A Retrospective Pilot Study

Alveolar ridge preservation (ARP) reduces dimensional changes following tooth extraction. We evaluated the changes in alveolar ridge dimensions after ARP using bone substitutes and collagen membranes. Objectives included the tomographic evaluation of sites prior to extraction and six months after ARP and the assessment of the extent ARP preserved the ridge and reduced the need for additional augmentation at the time of implant placement. A total of 12 participants who underwent ARP in the Postgraduate Periodontics Clinic (Faculty of Dentistry) were included. Cone beam computed tomography images were used to retrospectively assess 17 sites prior to and six months after dental extraction. Alveolar ridge changes were recorded and analysed using reproducible reference points. The alveolar ridge height was measured at buccal and palatal/lingual aspects, whilst width was measured at crestal level, 2 mm, 4 mm and 6 mm below the crest. Statistically significant changes were found in alveolar ridge width at all four heights, with mean reduction differences ranging from 1.16 mm to 2.84 mm. Likewise, significant changes in the palatal/lingual alveolar ridge height (1.28 mm) were observed. However, changes of 0.79 mm in buccal alveolar ridge height were not significant (p = 0.077). Although ARP reduced dimensional changes following a tooth extraction, some degree of alveolar ridge collapse could not be avoided. The amount of resorption on the buccal aspect of the ridge was less compared to the palatal/lingual after ARP. This indicated that the use of bone substitutes and collagen membranes was effective in reducing changes in the buccal alveolar ridge height.

Unravelling Alveolar Bone Regeneration Ability of Platelet-Rich Plasma: A Systematic Review with Meta-Analysis

Background: This systematic review aims to evaluate the efficacy of the available platelet-rich plasma (PRP) products and composition to regenerate alveolar bone after tooth extraction. Methods: PubMed, Cochrane Central Register of Controlled Trials, and EBSCO databases were searched up to 2 July 2021. Only randomized clinical trials using leukocyte-rich plasma (L-PRP) or pure-platelet rich plasma (P-PRP) for bone regeneration in alveolar ridge preservation were selected. The following outcomes were considered: (1) new bone formation (primary outcome) and (2) bone density (secondary outcome). A meta-analysis for PRP, P-PRP, and L-PRP using a fixed effect model was performed with Review Manager 5.4 software. Overall evidence was qualified using GRADE. Results: Six randomized clinical trials from 2639 unique articles initially identified met the inclusion criteria. The meta-analysis showed a significant effect of the P-PRP on the outcome of new bone formation (SMD, 1.44; 95% CI, 0.84 to 2.03) for P-PRP treatment. No information was retrieved for L-PRP. A statistically significant difference was also observed in the P-PRP group for bone density outcome (SMD, 1.24; 95% CI, 0.81 to 1.68). The L-PRP treated sockets also showed higher bone density (SMD, 0.88; 95% CI, 0.31 to 1.45) in comparison to control sockets. The quality of evidence was moderate for both outcomes in the P-PRP group and low for the L-PRP group. Conclusions: Despite the limitations of the included studies, our data suggest that P-PRP, in comparison to unassisted healing, can improve alveolar bone regenerative potential. However, more high-quality clinical studies are needed.

Ridge preservation using Collacone compared with an empty socket: a pilot study

OBJECTIVES

The objective of this study was to evaluate the dimensional changes in alveolar bone and soft tissue after dental extraction/postextraction in alveoli filled/grafted with collagen (Collacone) compared with those left empty/ungrafted.

STUDY DESIGN

Twenty-three patients with a single maxillary incisor to be extracted were included in the study. The patients were randomized into either the treatment group, receiving a collagen sponge, or into the control group with an empty alveolus. All participants were examined and followed with cone beam computed tomography and 3-dimensional soft tissue scanning procedures during the healing process. The outcomes were statistically evaluated with Mann-Whitney U tests.

RESULTS

Seventeen patients were available for follow-up. The radiographic outcome showed an average loss of bone in the bucco-palatal width of 1.15 mm (range, 0.2-2.2) in the test group and 0.57 mm (range, 0-1.6) among the controls. There was no significant difference between the 2 groups (P = .092). The soft tissue topography height measurements revealed an average decrease of 1.737 mm (range, 0.118-2.872) in the test group and 1.899 mm (range, 0.454-3.014) in the control group. The difference was not significant (P = .847).

CONCLUSION

The use of a Collacone collagen sponge does not enhance the bone and soft tissue healing outcome after extraction of an incisor in the maxilla compared with leaving the alveolus empty.

Facial cortical bone regeneration post-extraction in non-grafted sockets allows for early implant placement and long-term functional stability

OBJECTIVE

To evaluate posterior implant placement feasibility shortly after tooth extraction in non-grafted sockets with and without dehiscence at the time of extraction.

DESIGN

Ninety-five patients requiring posterior extractions entered this cross-sectional study. They were divided in three groups after extraction: G1 without dehiscence, G2 with dehiscence ≤5 and G3 > 5 mm. CBCT were taken prior to implant placement at an average of 12-weeks post-extraction to evaluate the need for grafting, cortical bone formation and bucco-lingual width (BLW). Actual BLW (n = 60) were compared to minimum expected BLW in 3 scenarios of BLW thickness averaging 6.4-7.4-8.4 mm. Peri-implant tissues were assessed for pocket formation and inflammation following established success criteria.

RESULTS

New cortical bone formation and sufficient BLW made implant placement feasible in sites with and without dehiscence at the time of extraction after an average healing time of 11.9 ± 2.4weeks (range: 8-18). Total average CBCT BLW was 10.1 ± 1.6 mm. All groups had a significantly higher BLW, than scenarios 1-3 (p < 0.0001). Molars were 20 times more likely than premolars to heal with BLW>10 mm (OR = 20; RR = 4.2; CI95 %: 5.3-74.2; p < 0.0001). Dehiscence sockets were 1.5 times more likely than non-dehiscenced sockets to present BLW ≤ 10 mm (OR = 1.5; RR = 0.6; CI95 %:0.9-2.5; p = 0.08). A band of keratinized tissue was present in all implants and success rates were 100 % at an average follow-up of 51.0 ± 23.4 months.

CONCLUSION

Implant placement is feasible without socket grafting shortly after tooth extraction. Non-grafted sockets present a significant osteogenic potential. Dehiscence sockets are likely to self-repair by forming a new cortical plate. The unassisted regenerated intra-socket bone allows for functional implant stability long-term.

Effect of platelet-rich fibrin on alveolar ridge preservation: A systematic review

BACKGROUND

Platelet-rich fibrin (PRF) is the second generation of platelet concentrates and is used in many areas of dentistry. However, whether PRF is effective for alveolar ridge preservation remains controversial. The authors conducted research to evaluate the potential of PRF to preserve the alveolar ridge.

METHODS

A comprehensive literature search was conducted in MEDLINE, Cochrane Central Register of Controlled Trials, and Embase. Only randomized controlled trials were included. A systematic review was made for postoperative pain, soft-tissue healing, bone density, horizontal and vertical ridge dimension changes, and histologic analysis. The meta-analysis was performed on the alveolar osteitis, mesial and distal bone height changes, and bone fill with Review Manager Version 5.3 software.

RESULTS

Among the 588 eligible articles found in the initial search, 7 published studies from 2012 through 2019 were included. The authors' qualitative analysis showed that PRF may play a positive role in reducing postoperative pain and ridge dimension changes after tooth extraction. Among the 7 articles, only 2 trials assessed the effect of PRF on the alveolar osteitis, mesial and distal bone height changes, and bone fill. Results of our meta-analysis showed that smaller mesial bone height changes (standard mean difference, -1.07; 95% confidence interval, -1.92 to 0.22) and a greater percentage of bone fill (standard mean difference, 0.82; 95% confidence interval, 0.32 to 1.33) were observed in the PRF group.

CONCLUSIONS

Given the potential value of PRF, consideration should be given to PRF after tooth extraction. However, more high-quality trials are necessary to evaluate the exact role of PRF.

PRACTICAL IMPLICATIONS

Based on the authors' results, the usage of PRF was suggested in alveolar ridge preservation.

Does Smoking Impair Bone Regeneration in the Dental Alveolar Socket?

Smoking is a major risk factor for dental implant failure. In addition to higher marginal bone loss around implants, the cellular and molecular responses to injury and implant physicochemical properties are also differentially affected in smokers. The purpose of this work is to determine if smoking impairs bone microstructure and extracellular matrix composition within the dental alveolar socket after tooth extraction. Alveolar bone biopsies obtained from Smokers (> 10 cigarettes per day for at least 10 years) and Ctrl (never-smokers), 7-146 months after tooth extraction, were investigated using X-ray micro-computed tomography, backscattered electron scanning electron microscopy, and Raman spectroscopy. Both Smokers and Ctrl exhibited high inter- and intra-individual heterogeneity in bone microstructure, which varied between dense cortical and porous trabecular architecture. Regions of disorganised/woven bone were more prevalent during early healing. Remodelled lamellar bone was predominant at longer healing periods. Bone mineral density, bone surface-to-volume ratio, mineral crystallinity, the carbonate-to-phosphate ratio, the mineral-to-matrix ratio, the collagen crosslink ratio, and the amounts of amino acids phenylalanine and proline/hydroxyproline were also comparable between Smokers and Ctrl. Bone microstructure and composition within the healing dental alveolar socket are not significantly affected by moderate-to-heavy smoking.

Analysis of the Buccal Bone Plate, Root Inclination and Alveolar Bone Dimensions in the Jawbone. A Descriptive Study Using Cone-Beam Computed Tomography

Objectives

This study aims to determine if there are enough buccal alveolar bone thickness to perform an immediate dental implant placement in anterior and posterior maxillary teeth.

Material and Methods

A total of 1463 teeth were examined, from 202 cone-beam computed tomography scans with voxel sizes of 0.15 mm. On each tooth, the following measures were determined: the alveolar bone thickness in two locations; the vertical distance between the buccal alveolar crest and cementoenamel junction; the angle between the tooth's long axis and the alveolar bone axial inclination in the sagittal plane.

Results

In the most coronal location of maxillary teeth, the thickness of alveolar bone was lower than 0.6 (SD 0.6) mm in 50% of the teeth, and in the middle of the root the bone thickness was, on average, 0.96 (SD 0.6) mm. For the same maxillary teeth, the vertical distance between the buccal alveolar crest and cementoenamel junction and the angulation measured were, on average, 3.6 (SD 1.2) mm and 12.1º (SD 1.4º), respectively.

Conclusions

The present study revealed that in most cases the thickness of buccal alveolar bone was less than 1 mm. Consequently, in such cases, immediate dental implant placement operation is not recommended, or should be combined with bone regeneration techniques.

Longitudinal assessment of clinical and radiographic periimplant status around narrow and regular diameter implants placed in cigarette-smokers and nonsmokers

BACKGROUND

To date, no clinical investigation has assessed the clinical and radiographic indices around narrow diameter implants (NDIs) and regular diameter implants (RDIs) in individuals with cigarette smoking habit and nonsmokers.

OBJECTIVE

To estimate and compare the clinical and radiographic indices around NDIs (< 3.3 mm) and RDIs placed in cigarette smokers (CS) and nonsmokers (NS).

MATERIALS AND METHODS

Eighty-six patients requiring implant surgery in the anterior mandible were divided into two groups (39 CS and 43 NS). Patients were further categorized into two subgroups on the basis of implant diameter: (a) patients with NDIs (3.3 mm) and (b) patients with RDIs (4.1 mm). Clinical indices evaluating plaque index (PI), bleeding on probing (BOP), and probing depth (PD) were recorded at 18 and 36 months of follow-up. Digital periapical radiographs were studied to evaluate crestal bone levels (CBL) incorporating in a specialized software and examined on a calibrated computer display screen with the help of an image analyzer.

RESULTS

The mean age of patients in CS group and NS group was 44.6 and 42.5 years, respectively. There was no statistically significant difference in the overall mean scores of PI, PD, and CBL around NDIs and RDIs among CS and NS patients at 18 and 36 months of follow-up. However, there was a statistically significant difference only in the overall mean BOP around NDIs and RDIs among CS and NS patients at 18 and 36 months of follow-up.

CONCLUSION

The findings of the current study suggests that NDIs can show reliable clinical stability and radiographic bone levels as RDIs placed in CS and NS, with the support of strict oral hygiene protocols.

Post extractive implant: evaluation of the critical aspects

Purpose

Nowadays, implant supported prosthetic rehabilitation is a reliable procedure to replace compromised or untreatable teeth. The purpose of this review is to explore the concept of post extractive implant and the indications for clinical practice through an analysis of recent studies in the literature. All the main factors that could influence the outcome of this treatment will also be considered.

Materials and methods

Focusing on the extraction-socket healing time, three different implant insertion protocols have been defined: Immediate implant placement (IIP), Early implant placement (EIP), Delayed implant placement (DIP). The entity of bone remodeling can be associated with different factors: three dimensional implant position, presence/absence of platform switching, absence of facial bony wall, inter implant/tooth distance.

Results

All the studies in literature agreed that implant primary stability is the main condition for a successful osseointegration of dental implants. Primary implant stability is influenced by many factors including local bone quality and quantity, implant macro-design, soft tissue conditions and rehabilitation, surgical technique, prosthetic load timing, oral hygiene.

Conclusions

There is insufficient evidence in literature to determine possible advantages or disadvantages of IIP, EIP or DIP. Studies suggest that IIP and EIP may be at higher risks of implant failures and complications than delayed implants; on the other hand the aesthetic outcome might be better when placing implants just after teeth extraction.

Minimally invasive vertical versus conventional tooth extraction: An interrupted time series study

BACKGROUND

Minimally invasive vertical tooth extraction techniques have evolved in light of the limitations of conventional tooth extraction techniques and flap surgery in preserving the alveolar bone. The authors conducted a study to obtain data on the performance of a vertical extraction system. This included comparing the need for flap surgery using the vertical extraction system versus conventional tooth extraction techniques for the extraction of anterior teeth and premolars not suitable for forceps extraction.

METHODS

The authors conducted a prospective observational clinical study of the vertical extraction system versus conventional tooth extraction techniques using an interrupted time series in line with the Idea, Development, Exploration, Assessment, Long-term Follow-up collaboration framework for surgical innovation.

RESULTS

Overall, 276 of 323 teeth (85.4%) in 240 patients were successfully extracted using the vertical extraction system. Of the 47 failures in the vertical tooth extraction cohort, 18 required flap surgery, resulting in an overall incidence of flap surgery of 5.6% (95% confidence interval [CI], 3.2% to 8.7%). During the routine care period, of the 94 anterior teeth and premolars in 78 patients, 21 teeth could not be extracted using conventional techniques and required flap surgery, leading to an incidence of flap surgery of 22% (95% CI, 14% to 32%).

CONCLUSIONS

The results suggest that the vertical extraction system may be used with a high success rate for extraction of severely destroyed teeth, and its use may lead to a marked reduction in the need for flap surgery. Randomized clinical trials are needed to confirm the findings.

PRACTICAL IMPLICATIONS

The use of a vertical extraction system may lower the incidence of flap surgery.

Estimation of date of death through wound healing of an extraction socket: A case report

Surgical extraction of teeth due to dental pathologies is a relatively common procedure in modern man. The healing of the wound that results occurs in gradual and sequential stages, such that the analysis of this repair process can be very useful in forensic investigations on human remains. The following study reports on a particular case where the remodeling of a tooth socket allowed an estimation of the time that had elapsed from the day of the surgical extraction of the tooth to the time of death. The corpse was that of a woman of 34 years. It was in an advanced state of decomposition, as it was largely skeletonized. Macroscopic, radiographic, and histological examinations of the oral cavity showed the initial stages of alveolar bone remodeling of the first left mandibular molar, which was characterized by: (i) a small reduction in the vertical height of the vestibular surface with respect to the theoretical original position of the tooth; (ii) resorption of the intra-alveolar septum and lamina dura; and (iii) formation of new immature bone, which covered the entire inner surface of the socket. This study established that the subject died 13-42days after the tooth extraction. Knowing the date of the dental extraction provided by the police investigation, it was possible to provide an estimate of the date of death.

Strategies for alveolar ridge reconstruction and preservation for implant therapy

PURPOSE

In dental implant treatment, ridge preservation and immediate or early implant placement are recommended to minimize bone resorption after tooth extraction and achieve esthetic outcomes. However, there is no consensus concerning the efficacy of this surgical method. There is also no consensus on the efficacy of bone and soft tissue grafts and surgical methods for alveolar ridge reconstruction.

STUDY SELECTION

This paper reports ridge alteration in the anterior maxilla after tooth extraction, and summarizes the efficacy of various ridge preservation methods and immediate or early implant placement as alveolar ridge preservation methods to minimize bone resorption after tooth extraction. The advantages and complications of alveolar ridge reconstruction methods, and the efficacy and surgical method of soft tissue graft are reviewed.

RESULTS

The anterior maxilla is in the esthetic zone, and the thickness of the bone on the labial side around the natural tooth is less than 1mm in many cases. Therefore, it is impossible to prevent bone resorption completely, even if ridge preservation and immediate or early implant placement are performed after tooth extraction. It is necessary to obtain stable and long-term esthetics by combining connective tissue and free gingival grafts, in addition to hard tissue augmentation.

CONCLUSIONS

It is important to consider the burden and level of satisfaction of patients, such as in terms of donor site morbidity in hard and soft tissue grafting, and to pay attention to appropriate indications to avoid overtreatment.

Current perspective of the impact of smoking on the progression and treatment of periodontitis

This literature review provides an overview of the current scenario regarding the impact of smoking on the progression and treatment of periodontitis; clinical, microbiological and immunological data from studies from our and other groups are presented. In general, preclinical and clinical data are unanimous in demonstrating that smokers present increased susceptibility, greater severity and faster progression of periodontal disease compared with nonsmokers. The evidence further demonstrates that smokers lose more teeth and have a less favorable response to therapy than do nonsmokers. Although it is well established that smoking significantly impacts on the onset, progression and outcome of periodontal disease, the mechanisms involved remain unclear. More importantly, some of the reported deleterious effects of smoking on periodontal tissues have been reported to be reversible upon participation in smoking-cessation programs. Therefore, clinicians should strongly advise smokers to enroll in cessation strategies, even temporarily, in order to improve the overall outcome.

Cigarette smoke inhalation influences bone healing of post-extraction tooth socket: a histometric study in rats

The aim of this study was to evaluate, histometrically, the bone healing of the molar extraction socket just after cigarette smoke inhalation (CSI). Forty male Wistar rats were randomly assigned to a test group (animals exposed to CSI, starting 3 days before teeth extraction and maintained until sacrifice; n=20) and a control group (animals never exposed to CSI; n=20). Second mandibular molars were bilaterally extracted and the animals (n=5/group/period) were sacrificed at 3, 7, 10 and 14 days after surgery. Digital images were analyzed according to the following histometric parameters: osteoid tissue (OT), remaining area (RA), mineralized tissue (MT) and non-mineralized tissue (NMT) in the molar socket. Intergroup analysis showed no significant differences at day 3 (p>0.05) for all parameters. On the 7(th) day, CSI affected negatively (p<0.05) bone formation with respect to NMT and RA (MT: 36%, NMT: 53%, RA: 12%; and MT: 39%, NMT: 29%, RA: 32%, for the control and test groups, respectively). In contrast, no statistically significant differences (p>0.05) were found at days 10 and 14. It may be concluded that CSI may affect socket healing from the early events involved in the healing process, which may be critical for the amount and quality of new-bone formation in smokers.

Plasma rich in growth factors in human extraction sockets: a radiographic and histomorphometric study on early bone deposition

OBJECTIVES

To determine whether and to what extent the additional application of plasma rich in growth factors (PRGF) to an extraction socket may influence the early bone deposition, as assessed by micro-computed tomography (micro-CT) scan as well as histomorphometric markers.

MATERIAL AND METHODS

Twenty-eight patients (age range: 34-74 years) contributing 36 extraction sockets were included in the study. Sockets were either treated with PRGF (PRGF group; 18 sites in 11 patients) or left to spontaneous healing (control group; 18 sites in 17 patients). Radiographic and histomorphometric analysis was performed on bone cores trephined from each healing socket after 4-6 (T1) or 7-10 (T2) weeks of healing.

RESULTS

Patients treated with PRGF application showed (i) similar bone volume and tissue mineral content, (ii) a trend, although not statistically significant, toward a greater number of CD68+ cells (at T1 and T2) and vVW+ cells (at T1), and (iii) a similar OCN staining score throughout the study, when compared with control group.

CONCLUSIONS

Plasma rich in growth factors-treated group did not show any enhancement in early (4 and 8 weeks) bone deposition compared with control group.

Alveolar bone healing process in spontaneously hypertensive rats (SHR). A radiographic densitometry study

Hypertension is one of the most important public health problems worldwide. If undiagnosed or untreated, this pathology represents a systemic risk factor and offers unfavorable conditions for dental treatments, especially those requiring bone healing.

OBJECTIVES

The purpose of this study was to demonstrate, by analysis of bone mineral density (BMD), that the alveolar bone healing process is altered in spontaneously hypertensive rats (SHRs).

MATERIAL AND METHODS

Wistar rats and SHRs were submitted to extraction of the upper right incisor and were euthanized 7, 14, 21, 28 and 42 days after surgery. Right maxillae were collected, radiographed and analyzed using Digora software. BMD was expressed as minimum (min), middle (med) and maximum (max) in the medium (MT) and apical (AT) thirds of the dental alveolus.

RESULTS

The results were compared across days and groups. Wistar showed difference in med and max BMD in the MT between 7 and 28 and also between 14 and 28 days. The AT exhibited significant difference in med and min BMD between 7 and 28 days, as well as difference in min BMD between 28 and 42 days. SHRs showed lower med BMD in the MT at 28 days when compared to 21 and 42 days. Differences were observed across groups in med and min BMD at day 28 in the MT and AT; and in max BMD at 14, 21 and 42 days in the MT.

CONCLUSIONS

These results suggest that the alveolar bone healing process is delayed in SHRs comparing with Wistar rats.

Alveolar ridge preservation. A systematic review

OBJECTIVE

The objective of this paper is to examine the effect of alveolar ridge preservation (ARP) compared to unassisted socket healing.

METHODS

Systematic review with electronic and hand search was performed. Randomised controlled trials (RCT), controlled clinical trials (CCT) and prospective cohort studies were eligible.

RESULTS

Eight RCTs and six CCTs were identified. Clinical heterogeneity did not allow for meta-analysis. Average change in clinical alveolar ridge (AR) width varied between -1.0 and -3.5 ± 2.7 mm in ARP groups and between -2.5 and -4.6 ± 0.3 mm in the controls, resulting in statistically significantly smaller reduction in the ARP groups in five out of seven studies. Mean change in clinical AR height varied between +1.3 ± 2.0 and -0.7 ± 1.4 mm in the ARP groups and between -0.8 ± 1.6 and -3.6 ± 1.5 mm in the controls. Height reduction in the ARP groups was statistically significantly less in six out of eight studies. Histological analysis indicated various degrees of new bone formation in both groups. Some graft interfered with the healing. Two out of eight studies reported statistically significantly more trabecular bone formation in the ARP group. No superiority of one technique for ARP could be identified; however, in certain cases guided bone regeneration was most effective. Statistically, significantly less augmentation at implant placement was needed in the ARP group in three out of four studies. The strength of evidence was moderate to low.

CONCLUSIONS

Post-extraction resorption of the AR might be limited, but cannot be eliminated by ARP, which at histological level does not always promote new bone formation. RCTs with unassisted socket healing and implant placement in the ARP studies are needed to support clinical decision making.

CLINICAL RELEVANCE

This systematic review reports not only on the clinical and radiographic outcomes, but also evaluates the histological appearance of the socket, along with site specific factors, patient-reported outcomes, feasibility of implant placement and strength of evidence, which will facilitate the decision making process in the clinical practice.

A systematic review of post-extractional alveolar hard and soft tissue dimensional changes in humans

BACKGROUND

Removal of teeth results in both horizontal and vertical changes of hard and soft tissue dimensions. The magnitude of these changes is important for decision-making and comprehensive treatment planning, with provisions for possible solutions to expected complications during prosthetic rehabilitation.

OBJECTIVES

To review all English dental literature to assess the magnitude of dimensional changes of both the hard and soft tissues of the alveolar ridge up to 12 months following tooth extraction in humans.

METHODS

An electronic MEDLINE and CENTRAL search complemented by manual searching was conducted to identify randomized controlled clinical trials and prospective cohort studies on hard and soft tissue dimensional changes after tooth extraction. Only studies reporting on undisturbed post-extraction dimensional changes relative to a fixed reference point over a clearly stated time period were included. Assessment of the identified studies and data extraction was performed independently by two reviewers. Data collected were reported by descriptive methods. Weighted means and percentages of the dimensional changes over time were calculated where appropriate.

RESULTS

The search provided 3954 titles and 238 abstracts. Full text analysis was performed for 104 articles resulting in 20 studies that met the inclusion criteria. In human hard tissue, horizontal dimensional reduction (3.79 ± 0.23 mm) was more than vertical reduction (1.24 ± 0.11 mm on buccal, 0.84 ± 0.62 mm on mesial and 0.80 ± 0.71 mm on distal sites) at 6 months. Percentage vertical dimensional change was 11-22% at 6 months. Percentage horizontal dimensional change was 32% at 3 months, and 29-63% at 6-7 months. Soft tissue changes demonstrated 0.4-0.5 mm gain of thickness at 6 months on the buccal and lingual aspects. Horizontal dimensional changes of hard and soft tissue (loss of 0.1-6.1 mm) was more substantial than vertical change (loss 0.9 mm to gain 0.4 mm) during observation periods of up to 12 months, when study casts were utilized as a means of documenting the changes.

CONCLUSIONS

Human re-entry studies showed horizontal bone loss of 29-63% and vertical bone loss of 11-22% after 6 months following tooth extraction. These studies demonstrated rapid reductions in the first 3-6 months that was followed by gradual reductions in dimensions thereafter.

Qualitative and quantitative evaluation of bony structures based on DICOM dataset

PURPOSE

The aim of this study was to investigate bone mass using different cone-beam computed tomographies (CBCTs) combined with image analysis and to determine whether bone quantity or quality was detected.

MATERIALS AND METHODS

Different measurements recorded on mandible bones of pigs in the retromolar region were evaluated on ProMax 3D (Planmeca Oy, Finland) and the ILUMA™CT (IMTEC™ Imaging, Ardmore, OK) to calculate a calibration curve. The spatial relationships of pig mandible halves relative to adjacent defined anatomical structures were assessed by means of 3D visualization software. In addition to the screenshot, their bone quality was evaluated in accordance with the Lenkholm and Zarb classification.

RESULTS

The CBCT calibration curves based on the measurements taken from the ProMax and ILUMA CT showed linear correlation. Huge Hounsfield units intervals were found between the 2 CBCTs and there was no correlation with the computed tomography. Exact information on the micromorphology of the bone cylinders was not available. A subjective correlation according to Lenkholm and Zarb showed overlapping in all groups.

CONCLUSIONS

CBCT is a good choice for analyzing bone mass. However, it does not provide any information on bone quality. To obtain information on the microarchitecture of the spongiosa, it is necessary to use a computed tomography with finite element analysis.

Healing of extraction sockets filled with BoneCeramic® prior to implant placement: preliminary histological findings

BACKGROUND

Various grafting materials have been designed to minimize edentulous ridge volume loss following tooth extraction by encouraging new bone formation in healing sockets. BoneCeramic® is a composite of hydroxyapatite and bèta-tricalcium phosphate with pores of 100-500 microns.

PURPOSES

The aim of this study was to evaluate bone regeneration in healing sockets substituted with BoneCeramic® prior to implant procedures.

MATERIALS AND METHODS

Fifteen extraction sockets were substituted with BoneCeramic® and 14 sockets were left to heal naturally in 10 patients (mean age 59.6 years). Biopsies were collected only from the implant recipient sites during surgery after healing periods ranging from 6-74 weeks (mean 22). In total, 24 biopsies were available; 10 from substituted and 14 from naturally healed sites. In one site, the implant was not placed intentionally and, in four substituted sites, implant placement had to be postponed due to inappropriate healing, hence from five sites biopsies were not available. Histological sections were examined by transmitted light microscope.

RESULTS

At the time of implant surgery, bone at substituted sites was softer than in controls, compromising initial implant stability. New bone formation at substituted sites was consistently poorer than in controls, presenting predominantly loose connective tissue and less woven bone.

CONCLUSION

The use of BoneCeramic® as a grafting material in fresh extraction sockets appears to interfere with normal healing processes of the alveolar bone. On the basis of the present preliminary findings, its indication as a material for bone augmentation, when implant placement is considered within 6-38 weeks after extraction, should be revised.

Cigarette smoke inhalation modulates gene expression in sites of bone healing: a study in rats

OBJECTIVE

The aim of this study was to assess the effect of cigarette smoke inhalation (CSI) on gene expression in alveolar bone healing sites.

STUDY DESIGN

Wistar rats were randomly assigned to the groups: control [animals not exposed to CSI (n = 20)] and test [animals exposed to CSI, starting 3 days before teeth extraction and maintained until killing them (n = 20)]. First mandibular molars were bilaterally extracted, and the expression of alkaline phosphatase, bone morphogenetic protein (BMP) 2 and 7, receptor activator of nuclear factor κB ligand, osteoprotegerin, and d2 isoform of vacuolar adenosine triphosphatase V(0) domain were assessed by quantitative polymerase chain reaction in the newly formed tissue in the sockets.

RESULTS

Overall, data analysis demonstrated that CSI significantly affected the expression pattern of all of the studied genes except BMP-7.

CONCLUSION

The expression of key genes for bone healing may be affected by CSI in tooth extraction sites.

Bone formation following implantation of bone biomaterials into extraction sites

BACKGROUND

Adequate bone volume is imperative for the osseointegration of endosseous implants, but postextraction resorption and remodeling may challenge implant placement. The use of bone biomaterials has been advocated to fill extraction sites and to enhance primary implant stability during osseointegration. The objective of the case series was to evaluate bone formation histologically and biomechanically in extraction sites following implantation of three commercially available bone biomaterials to compare their ability to allow guided bone regeneration.

METHODS

Thirty-six periodontally involved teeth were extracted from eight healthy non-smoking subjects. At least two bone biomaterials, a synthetic sponge based on polylactic-polyglycolic acid technology (FIS), bovine porous bone mineral (BPBM), or a natural coral derivative physically and chemically transformed into a calcium carbonate ceramic (COR), and one non-grafted control were applied to the extraction sockets within each subject and were covered by an expanded polytetrafluoroethylene device. The devices were removed after 2 months, and trephine biopsies were obtained from each site 4 months later. At that time, endosseous implants were placed in 25 of the sites, and healing abutments were placed; measurements were taken 4 to 6 months later with an electronic mobility testing device.

RESULTS

The percentage of residual biomaterial was 5.6% +/- 8.9% for FIS (P <0.001), 20.2% +/- 17.0% for BPBM (P <0.05), and 12.0% +/- 16.4% for COR (P <0.001). The amount of residual biomaterial after 6 months showed a significant relationship with the insertion torque measurements during the first third of implant insertion (P <0.05) and with values of the electronic mobility testing device at the abutment connection (P = 0.05). Histologically, new bone apposition was seen on BPBM particles. FIS sites showed similar ingrowth of blood vessels and osteocytes as empty controls.

CONCLUSION

All sites revealed good primary stability at implant insertion and proper implant rigidity at abutment placement, indicating that early implant osseointegration was not influenced by the application of bone biomaterials used in this study.

Implant Zones of the Jaws: Implant Location and Related Success Rate

The article demonstrates the factors of importance in the early and late failures of dental implants based on literature review. An implant location is one of many factors that can influence a success or failure of dental implants. The author identifies and describe four alveolar jaw regions--functional implant zones--with unique characteristics of anatomy, blood supply, pattern of bone resorption, bone quality and quantity, need for bone grafting and other supplemental surgical procedures, and a location-related implant success rate. The article discusses predisposing factors that can lead to early implant failures in different jaw zones. An implant location is investigated as one of these factors. A prior history of trauma to premaxillary region is described in the context of implant success in anterior maxilla. This zone is being referred by the author as the "traumatic zone." The challenges of mandibular posterior implant reconstruction are presented in the context of blood supply to the mandible. A deficiency of vascularization in this region, especially in elderly and edentulous patients, lead the author to refer to this zone as the "ischemic zone." The concept of relative ischemia of the posterior mandible that can develop with age and tooth loss is discussed. A thorough understanding of specifics of each functional implant zone should help to improve successes and prevent failures of dental implants.