The mylohyoid line is highly variable but does not affect the microarchitecture of the edentulous alveolar bone - an anatomical micro-CT study.

OBJECTIVES: To evaluate in the absence of teeth the variability of the mylohyoid line (ML), the microarchitecture of the adjacent bone, and whether the variable prominence/width of the ML is associated with the quality of the adjacent bone. METHODS: µCT scans of 28 human mandibles from anatomical specimens were analyzed. The following parameters were assessed in four edentulous areas (first and second premolar (PM), first, second, and third molar (M1/2/3)): ML width, cortical thickness (CtTh), average cortical- (Avg.Ct.BV/TV), and trabecular bone volume fraction (Avg.Tb.BV/TV). RESULTS: The ML width increased from the PM towards the M2 region, which also showed the highest variance (range: 0.4-10.2 mm). The CtTh showed a decrease in the M3 region, while Avg.Ct.BV/TV and Avg.Tb.BV/TV hardly differed among the regions. In the multivariable model on the effect of the various parameters on the ML width, only gender and tooth region were significant. Specifically, male specimens were associated with a wider ML width compared to female specimens and the M2 region was associated with a wider ML width compared to the other tooth regions. CONCLUSION: The ML width was not associated with the cortical and trabecular bone quality in the adjacent bone, while gender and tooth region had a significant effect. Specifically, the ML width was lower in female, but peaked in the M2 region with a median width of 3-4 mm. CLINICAL RELEVANCE: From a clinical point of view, it was confirmed that the ML is in general a highly variable structure, especially in the M2 region, but the ML width does not allow any conclusions on the bone quality. Altogether, this underlines the need for an individual and accurate diagnostic prior to any surgical intervention.

Hyaluronic acid in tooth extraction: a systematic review and meta-analysis of preclinical and clinical trials.

OBJECTIVES: To assess whether in animals or patients with ≥ 1 tooth extracted, hyaluronic acid (HyA) application results in superior healing and/or improved complication management compared to any other treatment or no treatment. MATERIALS AND METHODS: Three databases were searched until April 2022. The most relevant eligibility criteria were (1) local application of HyA as adjunct to tooth extraction or as treatment of alveolar osteitis, and (2) reporting of clinical, radiographic, histological, or patient-reported data. New bone formation and/or quality were considered main outcome parameters in preclinical studies, while pain, swelling, and trismus were defined as main outcome parameters in clinical studies. RESULTS: Five preclinical and 22 clinical studies (1062 patients at final evaluation) were included. In preclinical trials, HyA was applied into the extraction socket. Although a positive effect of HyA was seen in all individual studies on bone formation, this effect was not confirmed by meta-analysis. In clinical studies, HyA was applied into the extraction socket or used as spray or mouthwash. HyA application after non-surgical extraction of normally erupted teeth may have a positive effect on soft tissue healing. Based on meta-analyses, HyA application after surgical removal of lower third molars (LM3) resulted in significant reduction in pain perception 7 days postoperatively compared to either no additional wound manipulation or the application of a placebo/carrier. Early post-operative pain, trismus, and extent of swelling were unaffected. CONCLUSIONS: HyA application may have a positive effect in pain reduction after LM3 removal, but not after extraction of normally erupted teeth. CLINICAL RELEVANCE: HyA application may have a positive effect in pain reduction after surgical LM3 removal, but it does not seem to have any impact on other complications or after extraction of normally erupted teeth. Furthermore, it seems not to reduce post-extraction alveolar ridge modeling, even though preclinical studies show enhanced bone formation.

Preoperative buccal bone volume predicts long-term graft retention following augmentation in the esthetic zone: A retrospective case series.

OBJECTIVES: Buccal bone augmentation in the esthetic zone is routinely used to achieve optimal clinical outcomes. Nonetheless, long-term data are sparse, and it is unknown how baseline buccal bone volume affects the retention of the augmented volume over time. MATERIAL AND METHODS: This is a long-term follow-up retrospective case series. After a preoperative computed tomography scan, implants were placed in the anterior maxilla following guided bone regeneration, autogenous block grafting, or both. At the follow-up, patients received a computed tomography scan and a clinical examination. Buccal bone volume was the primary outcome. Buccal bone thickness, peri-implant, and esthetic parameters were secondary outcomes. RESULTS: After a median follow-up of 6.7 years (interquartile range: 4.9-9.4), 28 implants in 19 patients (median age at augmentation: 43.3 years, interquartile range: 34.4-56.7, 53% female) were followed up. Preoperative buccal bone volume at baseline (V0 ) showed a moderate correlation to final buccal bone volume (Vt , rs  = .43) but a strong correlation to the absolute volumetric change (ΔV = Vt -V0 , rs  = -.80). A linear mixed model for Vt had a large intercept of 91.39 (p < .001) and a rather small slope of .11 for V0 (p = .11). Observed differences between treatments were not statistically significant in the mixed model. V0 above 105 mm3 predicted a negative volume change (ΔV < 0) with a specificity of 100% and a sensitivity of 96%. CONCLUSIONS: The results suggest higher gains in sites with lower V0 and point to a cutoff V0 above which the augmented volume is not retained long-term.

How old is old for implant therapy in terms of implant survival and marginal bone levels after 5-11 years?

AIM: To evaluate implant survival and marginal bone levels (MBLevel ) at least 5 years after implant installation in patients ≥65 years old. METHODS: Patient records were screened retrospectively for the following inclusion criteria: (1) ≥65 years of age at the time of implant installation, and (2) ≥5-year radiographic follow-up or registered implant loss. Association between patient- and implant-related data with radiographically assessed data [i.e. implant survival, mean MBLevel (i.e. average of mesial and distal level) and maximum marginal bone loss (i.e. either mesial or distal loss; maximum MBLoss )] were statistically evaluated by mixed effects multi-level regression models. RESULTS: Two-hundred-eighteen implants in 74 patients were included with a mean follow-up of 6.2 years (range: 5 to 10.7 years); four early and six late implant losses have been registered (implant survival rate: 95.4%). Mean MBLevel and maximum MBLoss was 1.24 ± 0.9 mm and 1.48 ± 1.0 mm, respectively. Maximum MBLoss  < 2 mm, 2 to 5 mm and ≥5 mm was found in 70.7, 28.8 and 0.5% of the implants, respectively. For both, mean MBLevel and maximum MBLoss , age presented a slightly protective effect (mean MBLevel : Coef. -0.041, p = .016; maximum MBLoss : Coef. -0.045, p = .014). CONCLUSION: The high implant survival rate (95.4%), low mean MBLevel (1.24 mm) and low frequency of maximum MBLoss  ≥ 5 mm (0.5%) observed herein after 5 to 11 years follow-up suggest that older age should not be considered as a limiting factor for implant treatment.

Resonance frequency analysis of implants placed in condensed bone.

OBJECTIVES: Resonance frequency analysis (RFA) is used to monitor implant stability. Its output, the Implant Stability Quotient (ISQ), supposedly correlates with insertion torque, a common measurement of primary stability. However, the reliability of RFA in condensed bone remains unclear. MATERIAL AND METHODS: In this human cadaver study in edentulous jaws and fresh extraction sockets, implants were inserted using a split-mouth approach into condensed or untreated bone. Mean ISQ, peak insertion torque, and pre- and postoperative bone volume fractions (BV/TV) were assessed. RESULTS: In edentulous jaws, insertion torque and ISQ correlated both in untreated (r = 0.63, p = 0.02) and in condensed (r = 0.82, p  < 0.01) bone. In extraction sockets, insertion torque and ISQ only correlated in untreated (r = 0.78, p < 0.01), but not in condensed bone (r = 0.15, p = 0.58). In all edentulous jaws, preoperative BV/TV correlated with insertion torque (r = 0.90, p < 0.0001), ISQ (r = 0.64, p < 0.001), and changes in BV/TV (r = -0.71, p < 0.01). In all extraction sockets, preoperative BV/TV did not correlate with either insertion torque (r = 0.33, p = 0.15), ISQ (r = 0.38, p = 0.09), or changes in BV/TV (r = -0.41, p = 0.09). Joint analysis identified preoperative BV/TV as a predictor of postoperative BV/TV (p < 0.001), insertion torque (p < 0.001), and ISQ (p < 0.001). CONCLUSIONS: RFA is feasible for monitoring stability after late implant placement into condensed bone, but not after immediate placement into condensed fresh extraction sites.

A volumetric prediction model for postoperative cyst shrinkage.

OBJECTIVES: With only limited information available on dimensional changes after jaw cyst surgery, postoperative cyst shrinkage remains largely unpredictable. We aimed to propose a model for volumetric shrinkage based on time elapsed since cyst surgery. MATERIAL AND METHODS: We used data from patients that underwent cyst enucleation or decompression between 2007 and 2017 and had at least three computed tomography (CT) scans per patient. We fitted one simple exponential decay model [V(t) = V0 · e-ɑt] and one model with a patient-specific decay rate [Vk(t) = V0 · e-ßt + γkt]. RESULTS: Based on 108 CT scans from 36 patients (median age at surgery: 45.5 years, IQR: 32.3-55.3, 44% female), our simple exponential decay model is V(t) = V0 · e-0.0035t where V(t) is the residual cyst volume after time t elapsed since surgery, V0 is the initial cyst volume, and e is the base of the natural logarithm. Considering a patient-specific decay rate, the model is Vk(t) = V0 · e-0.0049t + γkt where γk is normally distributed, with expectation 0 and standard deviation 0.0041. CONCLUSIONS: Using an exponential regression model, we were able to reliably estimate volumetric shrinkage after jaw cyst surgery. The patient-specific decay rate substantially improved the fit of the model, whereas adding specific covariates as interaction effects to model the decay rate did not provide any significant improvement. CLINICAL RELEVANCE: Estimating postoperative cyst shrinkage is relevant for both treatment planning of jaw cyst surgery as well as evaluating the clinical success of the surgical approach.

Is MRI a viable alternative to CT/CBCT to identify the course of the inferior alveolar nerve in relation to the roots of the third molars?

OBJECTIVES: To assess the reliability of judging the spatial relation between the inferior alveolar nerve (IAN) and mandibular third molar (MTM) based on MRI or CT/CBCT images. METHODS: Altogether, CT/CBCT and MRI images of 87 MTMs were examined twice by 3 examiners with different degrees of experience. The course of the IAN in relation to the MTM, the presence/absence of a direct contact between IAN and MTM, and the presence of accessory IAN were determined. RESULTS: The IAN was in > 40% of the cases judged as inferior, while an interradicular position was diagnosed in < 5% of the cases. The overall agreement was good (κ = 0.72) and any disagreement between the imaging modalities was primarily among the adjacent regions, i.e., buccal/lingual/interradicular vs. inferior. CT/CBCT judgements presented a very good agreement for the inter- and intrarater comparison (κ > 0.80), while MRI judgements showed a slightly lower, but good agreement (κ = 0.74). A direct contact between IAN and MTM was diagnosed in about 65%, but in almost 20% a disagreement between the judgements based on MRI and CT/CBCT was present resulting in a moderate overall agreement (κ = 0.60). The agreement between the judgements based on MRI and CT/CBCT appeared independent of the examiner's experience and accessory IAN were described in 10 cases in MRI compared to 3 cases in CT/CBCT images. CONCLUSIONS: A good inter- and intrarater agreement has been observed for the assessment of the spatial relation between the IAN and MTM based on MRI images. Further, MRI images might provide advantages in the detection of accessory IAN compared to CT/CBCT. CLINICAL RELEVANCE: MRI appears as viable alternative to CT/CBCT for preoperative assessment of the IAN in relation to the MTM.

Angular changes in implants placed in the anterior maxillae of adults: a cephalometric pilot study.

OBJECTIVES: Completion of adolescent growth represents the earliest time point for implant placement, yet craniofacial growth persists into adulthood and may affect implant position. We aimed to assess whether implants placed in the anterior maxillae of adults show angular changes over time. MATERIAL AND METHODS: We conducted a cephalometric pilot study in postpubertal patients with no growth disorders, skeletal malformations, or parafunctions. The patients received a single implant in the anterior maxilla and no orthodontic or orthognathic treatment afterwards. We measured angular changes of implants and central incisors on cephalograms taken immediately and after at least 5 years postoperatively with the Sella-Nasion line (SNL) and the nasal line (NL) as references. Changes in implant-SNL angles were the primary outcome. RESULTS: In 21 patients (30.2 ± 11.5 years at surgery) after a mean follow-up of 8.6 ± 1.3 years, implant-SNL angles and implant-NL angles changed in 81% and 57% of implants, respectively. Implant-SNL changes ranged from 3° counterclockwise to 4° clockwise and were more prevalent in males (100% vs. 58%) and patients under 30 at surgery (85% vs. 63%); mean absolute differences were larger in males (1.8 ± 1.0° vs. 1.3 ± 1.4°) and patients under 30 at surgery (1.5 ± 1.4° vs. 1.1 ± 1.4°). Incisor-SNL angles and incisor-NL angles changed in 89% and 32% of incisors, respectively. CONCLUSIONS: Implants placed in the anterior maxillae of adults show modest angular changes over time. CLINICAL RELEVANCE: Changes in implant angles have potential functional and esthetic consequences.

An advanced prediction model for postoperative complications and early implant failure.

OBJECTIVES: Risk prediction in implant dentistry presents specific challenges including the dependence of observations from patients with multiple implants and rare outcome events. The aim of this study was to use advanced statistical methods based on penalized regression to assess risk factors in implant dentistry. MATERIAL AND METHODS: We conducted a retrospective study from January 2016 to November 2018 recording postoperative complications including bleeding, hematoma, local infection, and nerve damage, as well as early implant failure. We further assessed patient- and implant-related risk factors including smoking and diabetes, as well as treatment parameters including types of gaps and surgical procedures. Univariable and multivariable generalized estimating equation (GEE) models were estimated to assess predictor effects, and a prediction model was fitted using L1 penalized estimation (lasso). RESULTS: In a total of 1,132 patients (mean age: 50.6 ± 16.5 years, 55.4% female) and 2,413 implants, postoperative complications occurred in 71 patients. Sixteen implants were lost prior to loading. Multivariable GEE models showed a higher risk of any complication for diabetes mellitus (p = .006) and bone augmentation (p = .039). The models further revealed a higher risk of local infection for bone augmentation (p = .003), and a higher risk of hematoma formation for diabetes mellitus (p = .007) and edentulous jaws (p = .024). The lasso model did not select any risk factors into the prediction model. CONCLUSIONS: Using novel methodology well-suited to tackle the specific challenges of risk prediction in implant dentistry, we were able to reliably estimate associations of risk factors with outcomes.

Guided Lateral Sinus Lift Procedure Using 3-Dimensionally Printed Templates for a Safe Surgical Approach: A Proof-of-Concept Case Report.

The purpose of this article was to present a guided lateral window sinus lift procedure with the aid of a fully digital workflow using surgical templates for window osteotomy preparation and implant placement. A 22-year-old patient with insufficient residual bone height in the posterior maxilla was treated with a maxillary sinus augmentation procedure with a lateral window technique and simultaneous implant installation using 3-dimensionally printed surgical guides. The surgical guides, used for the preparation of both the lateral window and the implant site according to the optimal prosthodontic and anatomic position, were based on a fully digital workflow and virtual pre-planning with modified implant-planning software. Successful functional and esthetic rehabilitation of the patient was accomplished using standard surgical techniques and instruments but an innovative method for the production and application of surgical templates ensured a precise and safe approach for the lateral window osteotomy preparation. This guided lateral window sinus lift technique may reduce the incidence of surgical complications and failures and enhance patient-related outcomes.

Which substances loaded onto collagen scaffolds influence oral tissue regeneration?-an overview of the last 15 years.

BACKGROUND: Collagen scaffolds are widely used for guided bone or tissue regeneration. Aiming to enhance their regenerative properties, studies have loaded various substances onto these scaffolds. This review aims to provide an overview of existing literature which conducted in vitro, in vivo, and clinical testing of drug-loaded collagen scaffolds and analyze their outcome of promoting oral regeneration. MATERIALS AND METHODS: PubMed, Scopus, and Ovid Medline® were systematically searched for publications from 2005 to 2019. Journal articles assessing the effect of substances on oral hard or soft tissue regeneration, while using collagen carriers, were screened and qualitatively analyzed. Studies were grouped according to their used substance type-biological medical products, pharmaceuticals, and tissue-, cell-, and matrix-derived products. RESULTS: A total of 77 publications, applying 36 different substances, were included. Collagen scaffolds were demonstrating favorable adsorption behavior and release kinetics which could even be modified. BMP-2 was investigated most frequently, showing positive effects on oral tissue regeneration. BMP-9 showed comparable results at lower concentrations. Also, FGF2 enhanced bone and periodontal healing. Antibiotics improved the scaffold's anti-microbial activity and reduced the penetrability for bacteria. CONCLUSION: Growth factors showed promising results for oral tissue regeneration, while other substances were investigated less frequently. Found effects of investigated substances as well as adsorption and release properties of collagen scaffolds should be considered for further investigation. CLINICAL RELEVANCE: Collagen scaffolds are reliable carriers for any of the applied substances. BMP-2, BMP-9, and FGF2 showed enhanced bone and periodontal healing. Antibiotics improved anti-microbial properties of the scaffolds.

How old is old for implant therapy in terms of early implant losses?

OBJECTIVES: To assess, retrospectively, whether older age has an impact on implant osseointegration when compared with younger age. METHODS: All patients ≥65 years old at implant installation, in an university setting over a time-period of 11.5 years, with complete anamnestic data and follow-up until prosthetic restoration were included, and any early implant loss (EIL; i.e. lack of osseointegration prior to or at the time-point of prosthetic restoration) was recorded. Further, one implant, from each of the elderly patients, was attempted matched to one implant in a younger patient (35 to <55 years old at implant installation) from the same clinic based on (a) gender, (b) implant region, (c) smoking status and (d) bone grafting prior to/simultaneously with implant installation. The potential impact of various local and systemic factors on EIL in the entire elderly population, and in the matched elderly and younger patient group was statistically assessed. RESULTS: Four hundred forty-four patients ≥65 years old (range 65.1-91.3; 56.8% female) receiving 1,517 implants were identified; 10 patients had one EIL each (implant/patient level: 0.66/2.25%). Splitting this patient cohort additionally into four age groups [65-69.9 (n = 213), 70-74.9 (n = 111), 75-79.9 (n = 80) and ≥80 (n = 40)], EIL was on the implant level 0.41, 0.83, 0.34 and 2.26%, respectively, (p = .102) and on the patient level 1.41, 2.70, 1.25 and 7.50%, respectively, (p = .104); multilevel analysis showed weak evidence of association of increasing age with higher EIL rate (p = .090). Matching was possible in 347 cases, and 5 (1.44%) and 9 (2.59%) EIL in the elderly and younger patients, respectively, were observed (p = .280). EIL could not be associated with any systemic condition or medication intake. CONCLUSIONS: Elderly patients ≥65 years old presented a similarly low EIL rate as younger patients 35 to <55 years old, while patients ≥80 years old may have a slight tendency for a higher EIL rate. Hence, ageing does not seem to compromise osseointegration, and if at all, then only slightly and at a later stage of life.

Micro-CT evaluation of the cortical bone micro-architecture in the anterior and posterior maxilla and the maxillary sinus floor.

OBJECTIVES: To perform a within-subject comparison of the cortical bone micro-architecture of the maxillary sinus floor (MSF) to that of the buccal aspect of the anterior and posterior maxilla. METHODS: Micro-CT scans of the buccal aspect of the anterior and posterior maxilla and of the MSF in 14 human anatomical specimens were recorded. Within-subject comparisons were performed for cortical thickness (Ct.Th) and porosity (Ct.Po), average pore volume (AvgPo.V), and pore density (Po.Dn). RESULTS: The MSF presented the lowest and the anterior maxilla the highest Ct.Th, while Ct.Po was significantly higher at the MSF compared to the posterior maxilla (p = 0.021). No relevant differences were recorded for AvgPo.V and Po.Dn among regions (p > 0.067). Further, an increased Ct.Th at the MSF was significantly associated with a lower Po.Dn, while a higher Ct.Th and an increased AvgPo.V in the anterior maxilla were associated with a higher Ct.Th and an increased AvgPo.V, respectively, in the posterior maxilla and MSF. Finally, within each region, the AvgPo.V was associated positively with Ct.Po and negatively with Po.Dn. CONCLUSIONS: The cortical bone of the MSF is slightly less thick and slightly more porous compared to the cortical bone at the buccal aspect of the anterior and posterior maxilla. CLINICAL RELEVANCE: During lateral and vertical bone augmentation procedures, the cortical recipient bone is perforated several times to open the bone marrow compartment to facilitate provision of osteoinductive cells and molecules in the augmented space. Whether it is meaningful to approach the MSF in a similar way during MSF augmentation procedures or whether the slightly more porous structure of the MSF observed herein reduces the cortical barrier function already sufficiently has to be assessed in future clinical trials.

The Influence of Type 2 Diabetes Mellitus on the Osseointegration of Titanium Implants With Different Surface Modifications-A Histomorphometric Study in High-Fat Diet/Low-Dose Streptozotocin-Treated Rats.

OBJECTIVES: Type 2 diabetes mellitus (T2DM) is a systemic disease that also compromises the bone healing capacity. In healthy individuals, surface modifications of dental implants are proven to increase bone response and implant success. The aim of this study was to clarify if the surface modifications also improve osseointegration in a setting with diabetes mellitus. METHODS: T2DM was induced in 7 rats by a high-fat diet/low-dose streptozotocin injection. All animals received a hydroxyapatite (HA) implant, a sandblasted and acid-etched (SLA) implant, and a standard machined titanium implant for control in the tibia. After 4 weeks, thin-ground sections were produced, and the volume of new bone formation (nBV/TV) and bone-to-implant contact (nB.I/Im.I) were histomorphometrically analyzed. RESULTS: Both surface modifications led to an increase of osseointegration compared with the machined surface implant in rats with T2DM. nBV/TV was highest in the SLA implants, whereas nB.I/Im.I was highest in the HA group. Regardless of the surface modification, a superordinate regional pattern of new bone formation over the length of the implant was observed. CONCLUSIONS: Implants with HA coating and SLA surface modifications seem to have the potential to increase osseointegration also in T2DM rats when compared with a conventional machined surface.

Variation in bucco-palatal maxillary sinus width does not permit a meaningful sinus classification.

OBJECTIVES: The bucco-palatal sinus width (SW) appears as relevant factor for graft consolidation after maxillary sinus (MS) floor augmentation. The present study aimed to assess (a) SW at different height levels of posterior teeth, (b) possible factors influencing SW, and (c) whether a simple/meaningful sinus classification based on SW is possible. METHODS: The following parameters were recorded on computed tomographies of 76 edentulous and 86 partially edentulous maxillary quadrants displaying 383 tooth sites in total: (a) alveolar ridge height, (b) -area, (c) -width 2 mm apical to the alveolar crest, (d) -width at the sinus floor, and (e) SW and sinus area at a level 2, 4, 6, 8, and 10 mm above the sinus floor. The possible influence of gender, tooth position [i.e., premolar (PM); molar (M)], tooth-gap extent, and residual alveolar ridge dimensions on SW was assessed. Further, based on percentiles of average values or on the frequency distribution of SW <10, 10-15, or >15 mm, it was attempted to classify the sinus at each given site into narrow, average, or wide. RESULTS: Gender and tooth-gap extent presented no relevant impact on MS dimensions; however, significant differences were observed among the various tooth positions regarding all evaluated parameters. The lower the residual alveolar ridge, the wider the MS at 4-10 mm height, while the wider the residual alveolar ridge, the wider the MS. Large variation in SW classes among the different height levels within the same tooth position and among tooth positions within the same person was observed, irrespective of the threshold applied. Further, at a MS height of 10 mm at PM1, PM2, M1, and M2, SW was <10 mm in 68%, 33%, 0%, and 7% of the cases, respectively, while in 3%, 21%, 65%, and 57%, respectively, SW was >15 mm. CONCLUSIONS: There is a large variation in SW depending on the height level within the sinus and on tooth position, which does not permit a simple/meaningful classification of each sinus as "narrow," "average," or "wide." Nevertheless, narrow sinuses (<10 mm) are rather prevalent in the premolar region, while wide sinuses (>15 mm) in the molar region; further, a wider and shorter residual alveolar ridge is associated with a wider SW.

Alveolar bone resorption after primary tooth loss has a negative impact on straightforward implant installation in patients with agenesis of the lower second premolar.

OBJECTIVES: To compare the alveolar bone dimensions in patients with lower second premolar (P2) agenesis prior to and after primary molar loss on CT scans, and assess the possibility for straightforward implant placement. METHODS: Alveolar bone dimensions were evaluated on 150 mandibular CT scans in three groups: (i) agenesis of P2, with the primary tooth in situ, and regularly erupted first premolar (P1) and molar (M1) (AW); (ii) agenesis of P2, without the primary tooth in situ for ≥3 m, but regularly erupted P1 and M1 (AWO); and (iii) P1, P2, and M1 regularly erupted (CTR). The possibility of straightforward placement of an implant 3.5 or 4.3 mm in Ø × 10 mm long was digitally simulated and compared to the actually performed treatment. RESULTS: Buccolingual width (7.3 ± 2.0 mm) at the coronal aspect of the ridge in the AWO group was statistically significantly smaller comparing with both the AW (9.2 ± 1.4 mm) and the CTR (9.5 ± 1.1 mm) group; width reduction appeared to be mainly due to "collapse" of the buccal aspect of the ridge. Simulated straightforward placement of implants with a diameter of 3.5 or 4.3 mm was possible in 62% and 56% of the cases in the AWO vs. 86% and 84% in the AW group (p = .006 and .002, respectively). Straightforward implant placement was actually possible in all patients (22) in the AW group, while 28% (11 of 39) of the patients in the AWO group needed additional hard tissue augmentation. CONCLUSIONS: Significant dimensional differences exist in the alveolar ridge, especially in the coronal part, at lower P2 agenesis sites missing the primary tooth for ≥3 m, when compared to P2 agenesis sites with the primary tooth in situ. It seems thus reasonable to advise that the primary second molar should be kept as long as possible, in order to facilitate straightforward implant installation and reduce the probability of additional bone augmentation procedures.

Peri-implant bone remodeling at the interface of three different implant types: a histomorphometric study in mini-pigs.

OBJECTIVES: The aim of this study was to perform a histomorphometric evaluation of the healing characteristics and jawbone remodeling processes in the peri-implant bone tissue of three commonly used implant surfaces, during the early weeks of osseointegration. MATERIAL AND METHODS: Dental implants with three different surfaces (anodically modified, hydroxyapatite (HA)-coated and machined) were inserted into the mandibular side-tooth region of twelve adult mini-pigs. Histomorphometric analyses were performed to evaluate remodeling processes 3, 6 and 12 weeks post-implantation. RESULTS: Only a few very early bone remodeling-resorption sites were found at 3 weeks. After 6 weeks, additional signs of remodeling-related reversal and bone formation were detectable in all three groups, which steadily increased until 12 weeks. At the latter time point, the amount of remodeled bone was significantly higher for the anodized and HA-coated surfaces than for the machined implants. CONCLUSION: The results of this study demonstrate that peri-implant bone remodeling can start as early as 3 weeks after implantation and continues at a substantial level up to 12 weeks. The anodic modification or HA coating of implant surfaces appears to accelerate the conversion of primary regenerated bone into more mature secondary lamellar bone. If this observation is of clinical relevance, it has to be clarified in studies that include longer observational time periods.

A wide mesio-distal gap in sites of congenitally missing maxillary lateral incisors is related to a thin alveolar ridge.

OBJECTIVES: To evaluate (i) a possible correlation between the mesio-distal gap width and the alveolar ridge (AR) dimensions in patients missing the maxillary lateral incisor (I2) either due to agenesis or loss and (ii) the possibility of straightforward implant placement based on simulation. METHODS: The bucco-palatal width, area, and height of the AR at the position of I2, and the mesio-distal gap width between the central incisor and the canine, were assessed in maxillary CT scans of three groups: Patients with (i) agenesis of I2 (TA ; n = 40); (ii) I2 regularly erupted but extracted (TL ; n = 24); (iii) I2 regularly erupted and in situ (C; n = 40). Further, the possibility of straightforward placement of an implant 3 or 3.5 mm in diameter ×10 mm in length, with 1 mm distance from the buccal and palatal plate of the alveolar ridge was simulated and compared to the actual treatment delivered. RESULTS: Bucco-palatal width and area of the AR at I2 and the adjacent teeth was significantly reduced in TA compared to TL and C. Further, in TA , but not TL , an increasing mesio-distal gap width between the central incisor and canine resulted in a significantly reduced bucco-palatal width of the edentulous AR. This impeded a simulated straightforward implant placement in >50% of the cases in TA , even with a reduced implant diameter. CONCLUSIONS: In patients congenitally missing I2, an increased mesio-distal gap width correlates significantly with reduced edentulous AR dimensions. A mesio-distal gap of >6 mm was associated with thin bucco-palatal alveolar ridges, precluding straightforward implant placement in 60-80% of the cases.

Multiple Perforations of the Sinus Floor During Maxillary Sinus Floor Augmentation to Provide Access to the Bone Marrow Space: A Technical Report.

INTRODUCTION: Sinus floor augmentation is a routinely used surgical technique for increasing the bone height/volume of the atrophic posterior maxilla. Optimal integration of the implanted augmentation material within the newly formed bone will-at least partly-depend on adequate vascularization to ensure sufficient recruitment of osteoblast and osteoclast precursor cells. METHODS: The present technical note describes a modification intended to facilitate increased blood inflow into the augmented space. After preparation of the lateral window and elevation of the Schneiderian membrane, the cortical bone of the sinus floor is perforated several times either by using a piezoelectric device or a microsurgical handpiece with the corresponding tip or bur; these perforations should extend into the trabecular bone. RESULTS AND CONCLUSION: The experiences with this modified technique after 12 patients are presented and discussed. It is expected that by means of this relatively simple technique, increased blood and cell inflow into the augmented space is achieved. This may, in turn, enhance new bone formation and improve the integration of the augmentation material.

A quantification of regenerated bone tissue in human sinus biopsies: influences of anatomical region, age and sex.

OBJECTIVES: Sinus augmentation is a standard procedure to increase vertical bone supply for dental implants in the atrophic posterior maxilla. Despite the longstanding application of this method, information about some basic factors that could potentially influence bone regeneration after sinus augmentation is rare. The objective of this study was therefore to quantify the impact of the maxillary region (premolar/molar) and patients' age and sex on bone regeneration after sinus grafting. MATERIAL AND METHODS: Sinus augmentation procedures were performed in 107 patients (66 female: 52.8 ± 11.0 years, 41 male: 50.6 ± 11.3 years). After 6 ± 1 months, 201 sinus biopsies were harvested and histomorphometrically analysed. Height (oldHt) and bone volume fraction of pristine bone (oldBV/TV), as well as the amount of new bone (newBV/TV) and bone-to-bone substitute contact (BBSC) in the augmentation area, were assessed. RESULTS: In women, newBV/TV in the augmented sinus decreased significantly by 0.22 ± 0.08% per year. In men, no similar trend was observed. There were strong influences of the maxillary region and the dimensions of the host bone. In the premolar region, newBV/TV was 23.1 ± 7.9% and 25.1 ± 10.1%; in the molar region, newBV/TV averaged 20.4 ± 9.4% and 17.8 ± 8.8% for women and men, respectively. The greater the thickness of the wall of the sinus floor (mainly in the former premolar region), the greater was the amount of new bone tissue formed in the spaces in-between bone substitute particles. CONCLUSIONS: These empirical results derived from a large human sample, link factors that influence the quality of biomaterial integration to the known clinical risks for the success of dental implants.