Terrence J. Griffin

Why do dental implants fail? Part II.

Dental implant failure has led to continuous innovations of various implant systems and to different interceptive treatment modalities. These concerns have also led to selection of implant designs that best suit the various types of bone. A checklist has been created to facilitate collection of data on the different factors associated with dental implant failure. The data gathered from this list are the basis of a multinational statistical analysis. This analysis will provide accurate information about the percentage of each element causing implant failure. Different causes of failure, such as host factors, surgical placement, and improper implant selection, were reviewed in Part I of this two-part series. This article discusses failure categories in terms of etiology, failure mode, failure type, failure origin, failure timing, responsible personnel, and different tissue types.

Ridge Preservation Using a Composite Bone Graft and a Bioabsorbable Membrane With and Without Primary Wound Closure: A Comparative Clinical Trial

BACKGROUND The aim of this single-masked, randomized controlled clinical trial is to compare hard and soft tissue changes after ridge preservation performed with (control, RPc) and without (test, RPe) primary soft tissue closure in a split-mouth design. METHODS Eleven patients completed this 6-month trial. Extraction and ridge preservation were performed using a composite bone graft of inorganic bovine-derived hydroxyapatite matrix and cell binding peptide P-15 (ABM/P-15), demineralized freeze-dried bone allograft, and a copolymer bioabsorbable membrane. Primary wound closure was achieved on the control sites (RPc), whereas test sites (RPe) left the membrane exposed. Pocket probing depth on adjacent teeth, repositioning of the mucogingival junction, bone width, bone fill, and postoperative discomfort were assessed. Bone cores were obtained for histological examination. RESULTS Intragroup analyses for both groups demonstrated statistically significant mean reductions in probing depth (RPc: 0.42 mm, P = 0.012; RPe: 0.25 mm, P = 0.012) and bone width (RPc: 3 mm, P = 0.002; RPe: 3.42 mm, P <0.001). However, intergroup analysis did not find these parameters to be statistically different at 6 months. The test group showed statistically significant mean change in bone fill (7.21 mm; P <0.001). Compared to the control group, the test group showed statistically significant lower mean postoperative discomfort (RPc 4 versus RPe 2; P = 0.002). Histomorphometric analysis showed presence of 0% to 40% of ABM/P-15 and 5% to 20% of new bone formation in both groups. Comparison of clinical variables between the two groups at 6 months revealed that the mucogingival junction was statistically significantly more coronally displaced in the control group than in the test group, with a mean of 3.83 mm versus 1.21 mm (P = 0.002). CONCLUSIONS Ridge preservation without flap advancement preserves more keratinized tissue and has less postoperative discomfort and swelling. Although ridge preservation is performed with either method, ≈27% to 30% of bone width is lost.

Effect of Single and Contiguous Teeth Extractions on Alveolar Bone Remodeling: A Study in Dogs

BACKGROUND Tooth extraction is associated with dimensional changes in the alveolar ridge. The aim was to examine the effect of single versus contiguous teeth extractions on the alveolar ridge remodeling. MATERIAL AND METHODS Five female beagle dogs were randomly divided into three groups on the basis of location (anterior or posterior) and number of teeth extracted - exctraction socket classification: group 1 (one dog): single-tooth extraction; group 2 (two dogs): extraction of two teeth; and group 3 (two dogs): extraction of three teeth in four anterior sites and four posterior sites in both jaws. The dogs were sacrificed after 4 months. Sagittal sectioning of each extraction site was performed and evaluated using microcomputed tomography. RESULTS Buccolingual or palatal bone loss was observed 4 months after extraction in all three groups. The mean of the alveolar ridge width loss in group 1 (single-tooth extraction) was significantly less than those in groups 2 and 3 (p < .001) (multiple teeth extraction). Three-teeth extraction (group 3) had significantly more alveolar bone loss than two-teeth extraction (group 2) (p < .001). The three-teeth extraction group in the upper and lower showed more obvious resorption on the palatal/lingual side especially in the lower group posterior locations. CONCLUSION Contiguous teeth extraction caused significantly more alveolar ridge bone loss as compared with when a single tooth is extracted.

Comparison of the anatomic crown width/length ratios of unworn and worn maxillary teeth in Asian and white subjects

STATEMENT OF PROBLEM Various aspects of anatomic tooth dimensions have been examined in a number of studies where data are primarily based on the measurements obtained from white subjects. Additional factors such as ethnicity should be considered to produce a more comprehensive analysis. PURPOSE The purpose of this study is to compare the anatomic crown dimensions of extracted maxillary teeth in Asian and white populations. MATERIAL AND METHODS The width/length ratio (%) was calculated with standardized digital images of extracted maxillary anterior teeth from 157 Asian and 142 white subjects. Statistical analysis was performed to compare the 4 tooth groups (central incisiors, lateral incisiors, canines, and premolars) of the 2 ethnicities. The distribution of the outcome variables were examined for normality with the Kolmigorov-Smirnov test. Independent sample t tests were used to examine differences in outcomes in Asian and white subjects. RESULTS There was a significant difference (P<.05) in the width/length ratios of all maxillary anterior teeth in Asian and white subjects. In addition, there was a significant difference in the width of unworn central incisors and the length of worn lateral incisors and canines. CONCLUSIONS Ethnicity influences width/length ratios for all 4 anterior maxillary teeth. Anterior maxillary teeth in Asian subjects appear to be more slender when compared with those in white subjects.

Guided Tissue Regeneration–Based Root Coverage With a Platelet Concentrate Graft: A 3-Year Follow-Up Case Series

BACKGROUND A platelet concentrate graft (PCG) was applied underneath the barrier membrane in guided tissue regeneration (GTR)-based root coverage procedures. The purpose of this case study was to assess the effectiveness of the technique and the long-term outcomes. METHODS Thirty-seven Miller Class I or II recession defects in six patients were treated using the PCG and a collagen membrane covered by an advanced mucogingival flap. Clinical parameters, such as vertical gingival recession depth (VRD), clinical attachment level (CAL), probing depth (PD), and width of keratinized tissue (WKT), were recorded presurgery (at baseline [BL]) and at 6 and 36 months of follow-up. The Wilcoxon signed-rank test and the Mann-Whitney test were used to assess statistical significance (alpha = 0.05). RESULTS Between BL and 6 months, there was a statistically significant reduction in VRD (from 2.81 +/- 0.88 mm to 0.30 +/- 0.48 mm) and PD (from 2.59 +/- 0.50 mm to 1.14 +/- 0.35 mm), as well as an improvement in CAL (from 5.41 +/- 0.86 mm to 1.43 +/- 0.66 mm). These results remained stable over the following 30 months. There was no statistically significant change in WKT during the initial 6 months; however, the increase in WKT was statistically significant at the 36-month follow-up. When comparing the healing between the maxillary and mandibular teeth at 6 months, the VRD reduction was statistically significantly greater in the maxillary teeth, but the difference was not statistically significant 30 months later. The average root coverage at 6 and 36 months was 89.86% +/- 15.85% and 85.86% +/- 18.16%, respectively, with complete root coverage in 24 (64.86%) and 21 (56.76%) of the 37 teeth. CONCLUSIONS The GTR-based technique using PCG was effective in reducing gingival recession. The outcomes remained stable for 3 years.

Double Flap Incision Design for Guided Bone Regeneration: A Novel Technique and Clinical Considerations

BACKGROUND Premature membrane exposure for guided bone regeneration may result in complications, such as inadequate bone regeneration, inflammatory reactions, and wound infection. This paper presents a clinical case of a novel incision-flap design used to advance the flap to enhance tension-free primary closure for the vertical ridge augmentation. METHODS A 61-year-old white man presented with the chief complaint of wanting to replace his posterior mandibular teeth. A severe alveolar bone deformity vertically and horizontally (Seibert Class III) was noticed, especially over the mental foramen area. A staged guided bone regeneration procedure prior to the implant installation was chosen as the most optimal treatment. A partial-thickness flap, separating the mucosal flap from the periosteum overlying the alveolar bone, was used to advance the flap. RESULTS During the healing period, neither soft tissue dehiscence nor membrane exposure were noted. Clinical and radiographic evaluation revealed a 4- to 5-mm gain in vertical height and a noticeable increase in horizontal thickness. After the 6 to 8 months of healing for both sites, two implants were placed on each side with good primary stability and without complications. CONCLUSIONS This technique facilitates flap advancement by the tension-free nature of the design and enhances soft tissue maintenance during the course of regeneration. This approach, the separation of the periosteal layer and the mucosal layer, can be used as an alternative to overcome some of the limitations with conventional technique.

Severe Periodontitis in a Patient With Hyperoxaluria and Oxalosis: A Case Report and Review of the Literature

BACKGROUND Hyperoxaluria is a metabolic disease with excessive urinary oxalate excretion that can be primary or secondary. Hyperoxaluria can result in chronic renal disease and renal failure. Calcium oxalate crystals can be deposited in oral tissues, and the disease can be associated with severe periodontitis and tooth loss. METHODS The periodontal condition of a 38-year-old patient with a diagnosis of hyperoxaluria and end-stage renal disease is presented. The patients periodontal status was monitored over a period of several weeks, and extracted teeth were submitted for histopathologic evaluation. RESULTS The patient was diagnosed with generalized severe periodontitis and external root resorption. Initial periodontal treatment consisting of oral-hygiene instructions and scaling and root planing was performed. However, despite an initial decrease of soft tissue inflammation, the patients periodontal condition deteriorated, and eventually, all teeth had to be extracted. The deposition of calcium oxalate crystals in the periodontal tissues was confirmed histologically. CONCLUSIONS Long-standing hyperoxaluria can be associated with severe periodontitis and external root resorption resulting in tooth loss. The pathogenetic mechanisms of hard tissue destruction are still unclear.

Comparison of double-flap incision to periosteal releasing incision for flap advancement: a prospective clinical trial.

PURPOSE The aim of this study was to evaluate the efficacy and morbidity of two periodontal releasing incision techniques in vertical ridge augmentation. MATERIALS AND METHODS Twenty-three vertical and horizontal defects (Seibert Class III) were selected to compare the double-flap incision (DFI) to the conventional periosteal releasing incision (PRI). An incision technique was randomly assigned for flap advancement. The amount of flap advancement, the incidence of postsurgical complications, and the level of patient discomfort were compared. Flap advancement was measured with a UNC-15 probe as the difference between the initial elevated flap and the final advanced flap. Postsurgical complications including premature membrane exposure, infection, paresthesia, and continuous discomfort were noted at follow-up visits. A visual analog scale (VAS) was used to quantify the amount of pain, swelling, and bleeding in the patients. RESULTS An average of 9.64 ± 0.92 mm flap advancement was accomplished for DFI, whereas PRI advancement averaged 7.13 ± 1.45 mm (P < .001). Premature membrane exposures occurred in two sites in the PRI group and one site in the DFI group. Paresthesia, infection, and continuous discomfort were noted in one site each in the PRI group. The difference between groups in the incidence of postoperative complications (PRI, 5; DFI, 1) was not significant (P < .082). The mean pain, swelling, and bleeding scores for DFI (1.55 ± 1.21, 1.91 ± 0.94, and 0.40 ± 0.12, respectively) were lower than those of the PRI group (3.75 ± 2.63, 3.25 ± 1.29, and 1.16 ± 0.34, respectively) (P = .019, P = .010, and P = .061, respectively). CONCLUSIONS Flap advancement was facilitated and morbidity was decreased in the DFI group. The technique may have potential to serve as an alternative to PRI to overcome some of the latters limitations.

Effect of enamel matrix derivative protein on the healing of standardized epithelial wounds: a histomorphometric analysis in vivo.

The enamel matrix derivative (EMD) is a preparation of the enamel matrix proteins secreted by the Hertwigs epithelial root sheath. It has been shown that EMD promotes periodontal wound healing; however, the significance of the protein in repairing skin wounds is insufficiently addressed. The aim of this in vivo histomorphometric investigation was to analyse the effect of EMD protein on the healing of standardised epithelial wounds. Dorsal skin of 22‐week‐old female guinea pigs (n = 33) was scarified and divided into test‐ (topical application of EMD) and control‐sites (sutured and allowed to heal). Animals were euthanised at specific time intervals and the specimens were then evaluated histomorphometrically. The mean widths of the external wound gaps (WGs) in the test‐ and control‐sites at the 5th, 20th and 35th day of healing were 5·89, 3·6 and 1·01 mm and 6·41, 5·02 and 3·43 mm, respectively. Histomorphometric analysis showed a statistically significant difference in the WGs between the test‐ and control‐sites. A significant increase in the formation of organised connective tissue matrix, collagen fibres and early muscle formation was observed in the test‐sites as compared with the control‐sites. Within the limits of this study, it is concluded that topical application of the EMD on standardised epithelial allows early wound closure and promotes healing as compared to when the defects are merely sutured.

Early bone healing around 2 different experimental, HA grit-blasted, and dual acid-etched titanium implant surfaces. A pilot study in rabbits.

Purpose:To compare early bone healing around different experimental titanium implant surfaces and to evaluate the role of a calcium phosphate–coated implant surface because it relates to bone-implant contact (BIC). Methods:An experimental hydroxyapatite (HA) grit-blasted and dual acid-etched titanium surface (BAE-1) was compared to an experimental HA grit-blasted and dual acid-etched surface treated with nanometer-scale crystals of HA (BAE-2). Both experimental implant surfaces were implanted onto the tibias of 4 New Zealand white rabbits. The animals were killed at 1,6, 21, and 90 days after the implant surgery. Descriptive histology was performed at the healing responses of both implant surfaces. Quantitative morphology assessment provided measurements of BIC, number of bone multicellular units (BMUs), average penetration of BMUs, and maximum penetration of BMUs that were manually made using imaging computer software. Result:The overall BIC for the BAE-2 implant was higher than that for the BAE-1 implant at 21 days of healing. However, there was no significant difference at 90 days of healing. Conclusion:It is concluded from this animal pilot study that the bioactive BAE-2 implant surface provided a better BIC with healthy bone remodeling at 21 days of healing