Buccal Alveolar Crest Research Articles

Digital tooth-based superimposition method for assessment of alveolar bone levels on cone-beam computed tomography images

Cone-beam computed tomography images have been previously used for evaluation of alveolar bone levels around teeth before, during, and after orthodontic treatment. Protocols described in the literature have been vague, have used unstable landmarks, or have required several software programs, file conversions, or hand tracings, among other factors that could compromise the precision of the measurements. The purposes of this article are to describe a totally digital tooth-based superimposition method for the quantitative assessment of alveolar bone levels and to evaluate its reliability. Ultra cone-beam computed tomography images (0.1-mm reconstruction) from 10 subjects were obtained from the data pool of the University of Oklahoma; 80 premolars were measured twice by the same examiner and a third time by a second examiner to determine alveolar bone heights and thicknesses before and more than 6 months after orthodontic treatment using OsiriX (version 3.5.1; Pixeo, Geneva, Switzerland). Intraexaminer and interexaminer reliabilities were evaluated, and Dahlberg's formula was used to calculate the error of the measurements. Cross-sectional and longitudinal evaluations of alveolar bone levels were possible using a digital tooth-based superimposition method. The mean differences for buccal alveolar crest heights and thicknesses were below 0.10 mm for the same examiner and below 0.17 mm for all examiners. The ranges of errors for any measurement were between 0.02 and 0.23 mm for intraexaminer errors, and between 0.06 and 0.29 mm for interexaminer errors. This protocol can be used for cross-sectional or longitudinal assessment of alveolar bone levels with low interexaminer and intraexaminer errors, and it eliminates the use of less reliable or less stable landmarks and the need for multiple software programs and image printouts. Standardization of the methods for bone assessment in orthodontics is necessary; this method could be the answer to this need.

A Cone Beam Tomographic Evaluation of Hard Tissue Alterations at Immediate Implants: A Clinical Prospective Study

The aim of this study was to investigate the hard tissue alterations of the alveolar bone crest following tooth extraction and immediate implant placement using cone beam computed tomography. Twelve consecutive patients in need of an immediate dental implant were included in the study. An implant of proper length was placed in the extraction socket with the coronal margin of the rough surface generally flush with or deeper than the buccal alveolar bone crest. All patients underwent a radiologic examination both immediately after implant placement (T1) and at the time of reentry 4 months after surgery (T2). The survival rate of 12 immediate implants at 4 months was 100%. Only 9 of 12 patients completed the study. The comparison between tomographies performed at T1 and T2 showed substantial variations in alveolar bone, mainly at the buccal aspect, registering a vertical gain of about 3.2 mm. The horizontal resorption of the alveolar bone crest appeared to be more marked at the buccal than at the lingual aspects. At the buccal aspect, the resorption was 1.9 mm, 1.0 mm, and 0.6 mm at the measurements performed at 1, 3, and 5 mm apical to the crest, respectively. At the lingual aspect, the corresponding values were 0.6 mm, 0.7 mm, and 0.5 mm, respectively. The bone crest area was more or less the same at T1 and T2, while the total area decreased after 4 months of healing but was not statistically significant. The results should be viewed with caution because of the small number of cases examined. The results confirm the success of immediate implant placement.

Dimensional changes in soft tissues around dental implants following free gingival grafting: an experimental study in dogs

To study the buccal dimensional tissue changes at oral implants following free gingival grafting, with or without including the keratin layer, performed at the time of implant installation into alveolar mucosa. The mandibular premolars and first molars were extracted bilaterally in six Beagle dogs. In the right side of the mandible (Test), flaps were first elevated, and the buccal as well as part of the lingual masticatory mucosa was removed. An incision of the periosteum at the buccal aspect was performed to allow the flap to be coronally repositioned. Primary wound closure was obtained. In the left side, the masticatory (keratinized) mucosa was left in situ, and no sutures were applied (Control). After 3 months of healing, absence of keratinized mucosa was confirmed at the test sites. Two recipient sites were prepared at each side of the mandible in the region of the third and fourth premolars. All implants were installed with the shoulder placed flush with the buccal alveolar bony crest, and abutments were connected to allow a non-submerged healing. Two free gingival mucosal grafts were harvested from the buccal region of the maxillary canines. One graft was left intact (gingival mucosal graft), while for the second, the epithelial layer was removed (gingival connective tissue graft). Subsequently, the grafts were fixed around the test implants in position of the third and fourth premolars, respectively. After 3 months, the animals were euthanized and ground sections obtained. Similar bony crest resorption and coronal extension of osseointegration were found at test and control sites. Moreover, similar dimensions of the peri-implant soft tissues were obtained at test and control sites. The increase in the alveolar mucosal thickness by means of a gingival graft affected the peri-implant marginal bone resorption and soft tissue recession around implants. This resulted in outcomes that were similar to those at implants surrounded by masticatory mucosa, indicating that gingival grafting in the absence of keratinized mucosa around implants may reduce the resorption of the marginal crest and soft tissue recession.

Influence of presence or absence of keratinized mucosa on the alveolar bony crest level as it relates to different buccal marginal bone thicknesses. An experimental study in dogs

To investigate the influence of the presence or absence of keratinized mucosa on the alveolar bony crest level as it relates to different buccal marginal bone thicknesses. In six beagle dogs, the mandibular premolars and first molars were extracted bilaterally. In the right side of the mandible (test), flaps were elevated, and the buccal as well as part of the lingual masticatory mucosa was removed. The flap was released coronally to allow a primary wound closure. In the left side, the wounds were left unsutured with the keratinized mucosa remaining (control). After 3months of healing, a complete absence of keratinized mucosa was found at the test sites. Two recipient sites were prepared at each side of the mandible, one in the premolar and one in the molar region. A buccal bony ridge width of approximately 1 and 2mm was obtained at the premolar and molar region, respectively. Implants were installed with the shoulder flush with the buccal alveolar bony crest, and abutments were connected to allow a nonsubmerged healing. At least 2mm of keratinized mucosa was surrounding the control sites, while at the test sites, the implants were bordered by alveolar mucosa. After 3months, the animals were euthanized and ground sections obtained. A higher vertical bony crest resorption was observed at the test compared with the control sites both at the premolar and molar regions, the differences being statistically significant. The top of the peri-implant mucosa was located more coronally at the control compared with the test sites. The horizontal resorption measured 1mm below the implant shoulder was similar at the test and control sites. Only limited differences were found between premolar and molar sites, with the exclusion of the horizontal resorption that was higher at the test compared with the control sites. A higher alveolar buccal bony crest resorption and a more apical soft tissue marginal position should be expected, when implants are surrounded with thin alveolar mucosa at the time of installation, independently of the thickness of the buccal bony crest.

Aesthetic gingival management: Preservation of the anatomical structures and the gingival aesthetics by immediate implant-insertion after loss of anterior teeth and premolars—Results of a 5-year prospective study with 348 inserted one-phase implants

Implant insertion is an alternative to classical treatment with bridges after tooth extraction or traumatic tooth loss in the anterior and premolar region of the upper and lower jaw. Nevertheless both types of prosthetic treatment inhere major gingival aesthetic pitfalls by physiological vertical and horizontal resorption. Aim of the study was to investigate if the immediate insertion of root analogue single-stage implants and prosthetic treatment could prevent gingival recessions and bone resorption thus keeping the natural gingival aesthetics untouched. Between 2003 and 2006, 348 root analogue Q1-Implants (TRINON Karlsruhe GmbH/Germany) were inserted in 342 patients’s premolar and molar regions immediately after tooth extraction or traumatic tooth loss and treated with provisional resin crowns. The observation period with recurring 6-month clinical and radiographic check-ups was a minimum of 5 years. Of 348 inserted implants 4 (1.15%) were lost resulting in an overall success rate of 98.85%. In the first 12 weeks after surgery a mean recession of the buccal gingival margin of 0.2 mm (SD 0.34) could be detected, after final prosthetic treatment an overall mean recession of 0.2 mm (SD 0.13) within the survey period. Immediate implant insertion of root analogue single stage implants and immediate prosthetic treatment with provisional resin crowns after minimal invasive tooth extraction seems to be appropriate to prevent bone resorptions of the buccal alveolar crest and the recessions of the gingiva and papillae and thus suggests to be the preferable treatment to keep the natural gingival and papillary aesthetics untouched preventing further traumatic surgical gingival reconstructions.

Ridge preservation at implants installed immediately after molar extraction. An experimental study in the dog

To evaluate the influence of deproteinized bovine bone mineral (DBBM), in conjunction with a collagen membrane, on bone resorption at implants installed in a lingual position immediately into extraction sockets with horizontal residual buccal defects >2.0mm. The pulp tissue of the mesial roots of (1) M(1) was removed in six Labrador dogs, and the root canals were filled with gutta-percha and cement. Flaps were elevated. The molars were hemi-sectioned and the distal roots removed. Implants were installed in a lingual position and with the shoulder flush with the buccal bony crest. After installation, defects of about 2.5 and 2.7mm in width resulted at the buccal aspects of the test and control sites, respectively. Only in the left site (test), deproteinized bovine bone mineral (DBBM) particles were placed into the defect concomitantly with the placement of a collagen membrane. On the control sites, no biomaterials were applied. A non-submerged healing was allowed. After 3months of healing, one control implant was not integrated and was excluded from the analysis, together with the contralateral test implant. All remaining implants were integrated into mature bone. The buccal alveolar bony crest was resorbed more at the test compared with the control sites, 2.2±0.9mm and 1.5±1.3mm, respectively. The vertical resorption of the lingual plate was 1.6±1.5mm and 1.5±1.1mm at the test and control sites, respectively. Only small residual DBBM particles were found at the test sites (1.4%). The use of DBBM particles to fill buccal defects of ≥2.5mm at implants installed immediately into alveolar extraction sockets did not preserve the buccal bony wall.

Influence of buccal bony crest width on marginal dimensions of peri‐implant hard and soft tissues after implant installation. An experimental study in dogs

To evaluate the influence of the width of the buccal bony wall on hard and soft tissue dimensions following implant installation. Mandibular premolars and first molars of six Labrador dogs were extracted bilaterally. After 3months of healing, two recipient sites, one on each side of the mandible, were prepared in such a way as to obtain a buccal bony ridge width of about 2mm in the right (control) and 1mm in the left sides (test), respectively. Implants were installed with the coronal margin flush with the buccal alveolar bony crest. Abutments were placed and the flaps were sutured to allow a non-submerged healing. After 3months, the animals were euthanized and ground sections obtained. All implants were completely osseointegrated. In respect to the coronal rough margin of the implant, the most coronal bone-to-implant contact was apically located 1.04±0.91 and 0.94±0.87mm at the test and control sites, respectively, whereas the top of the bony crest was located 0.30±0.40mm at the test and 0.57±0.49mm at the control sites. No statistically significant differences were found. A larger horizontal bone resorption, however, evaluated 1mm apically to the rough margin, was found at the control (1.1±0.7mm) compared to the test (0.3±0.3mm) sites, the difference being statistically significant. A thin peri-implant mucosa (2.4-2.6mm) was found at implant installation while, after 3months of healing, a biological width of 3.90-4.40mm was observed with no statistically significant differences between control and test sites. A width of the buccal bony wall of 1or 2mm at implant sites yielded similar results after 3months of healing in relation of hard tissue and soft tissues dimensions after implant installation.

Effect of mismatching abutments on implants with wider platforms – an experimental study in dogs

To evaluate the effect of mismatching abutments on implants with a wider platform on the peri-implant hard tissue remodeling and the soft tissue dimensions. Mandibular premolars and first molars of six Labrador dogs were extracted bilaterally. After 3months of healing, one tapered implant was installed on each side of the mandibular molar region with the implant shoulder placed at the level of the buccal alveolar bony crest. On the right side of the mandible, an abutment of reduced diameter in relation to the platform of the implant was used, creating a mismatch of 0.85mm (test), whereas an abutment of the same diameter of the implant platform was affixed in the left side of the mandible (control). The flaps were sutured to allow a non-submerged healing. After 4months, the animals were sacrificed and ground sections were obtained for histometric assessment. All implants were completely osseo-integrated. Bone levels were superior at the test than at the control sites. However, statistically significant differences were found only at the buccal and proximal aspects. The soft tissue vertical dimension was higher at the control compared with the test sites. However, statistically significant differences were demonstrated only at the buccal aspects. A mismatch of 0.85mm between the implant and the abutment yielded more coronal levels of bone-to-implant contact and a reduced height of the peri-implant soft tissue (biologic width), especially at the buccal aspect, if the implant shoulder was placed flush with the level of the buccal alveolar bony crest.

Influence of implants with different sizes and configurations installed immediately into extraction sockets on peri‐implant hard and soft tissues: an experimental study in dogs

To study the influence on the healing of soft and hard peri-implant tissues when implants of different sizes and configurations were installed into sockets immediately after tooth extraction. Transmucosal cylindrical implants, 3.3mm in diameter in the control sites, and conical 5mm in diameter in the test sites, were installed into the distal socket of the fourth mandibular premolars in dogs immediately after tooth extraction. After 4months, the hard and soft tissue healing was evaluated histologically. All implants were integrated in mineralized mature bone. Both at the test and control sites, the alveolar crest underwent resorption. The buccal bony surface at the implant test sites (conical; 3.8mm) was more resorbed compared with the control sites (cylindrical; 1.6mm). The soft tissue dimensions were similar in both groups. However, in relation to the implant shoulder, the peri-implant mucosa was located more apically at the test compared with the control sites. The present study confirmed that the distance between the implant surface and the outer contour of the buccal alveolar bony crest influenced the degree of resorption of the buccal bone plate. Consequently, in relation to the implant shoulder, the peri-implant mucosa will be established at a more apical level, if the distance between the implant surface and the outer contour of the alveolar crest is small.

Periodontal effects of surgically assisted rapid palatal expansion evaluated clinically and with cone-beam computerized tomography: 6-month preliminary results

Transverse maxillary deficiency is frequently observed in patients who seek orthodontic treatment. In skeletally mature patients, transverse maxillary deficiency can be treated with surgically assisted rapid palatal expansion (SARPE). Forces delivered by the expander produce areas of compression in the periodontal ligament, which could lead to alveolar bone resorption and possible changes in the attachment level. The aim of this prospective clinical study was to evaluate the periodontal effects of SARPE by means of a complete clinical evaluation and cone-beam computerized tomography (CBCT) evaluation. The sample included 14 patients (5 males, 9 females), with a mean age of 23.0 ± 1.9 years (range: 16.4 to 39.7 years). All patients were treated using a bonded Hyrax-type expander, and the mean expansion was 9.82 mm (7.5 to 12.0 mm). All patients had a 1-year retention period. CBCT scans were taken, and periodontal charts were completed at time points T0 (initial) and T1 (6 months after expansion). SARPE seemed to have little detrimental clinical effects on the periodontium. Radiographic data demonstrated statistically significant changes: a significant decrease in the buccal alveolar bone thickness on most teeth, a significant increase in the palatal alveolar bone thickness on most teeth, a decrease in the buccal alveolar crest level of all canines and posterior teeth, and a tendency toward a decrease in the interproximal alveolar crest level on the mesial aspect of both central incisors. SARPE seems to have little detrimental effects on the periodontium clinically. However, radiographic data demonstrated some statistically significant changes, which could eventually have a significant clinical impact on the periodontium.

Analysis of the pattern of the alveolar ridge remodelling following single tooth extraction

Tooth extraction is followed by marked osseous changes of the residual alveolar ridge including severe bone alterations both in height and in width. However, such remodelling could jeopardize the subsequent implant insertion for two main reasons. Firstly, the absence of adequate bone levels makes implant placement impossible; secondly, aesthetic problems in the fabrication of implanto-supported restoration could be caused by serious bone re-absorption. Thus, it is of crucial importance that the dental surgeon knows how the alveolar crest changes when a single tooth has been removed. The aim of this study was to evaluate the pattern of alveolar crest remodelling observed in a single intercalated area of tooth extraction after at least a period of 6 months of healing, using standardized photos of model casts. Among the patients who were treated for a single intercalated tooth extraction during the last 2 years at the department of dentistry at Versilia Hospital, Lido di Camaiore (Lucca), Italy, we selected 50 patients. The amount of alveolar crest remodelling was assessed on standardized photos of study models. All measurement were recorded on an Excel sheet (Excel, Windows XP(®)) and each value was multiplied by the enlargement index so that true values of re-absorption could be obtained. Finally, we have calculated the percentage of amount of alveolar crest remodelling and shifting of alveolar crest. We calculated the percentage of buccal remodelling and alveolar crest shift. The buccal re-absorption was 19.4 ± 9.4% at mesial point, 39.1 ± 10.4% at midpoint and 20.3 ± 10.7% at distal level. Moreover, the shift of the alveolar crest was 59.1 ± 11.2% at mesial point, 64.8 ± 10.5% at the midpoint and 56 ± 12.5% at distal point. This study confirmed that buccal wall tends to re-absorb after the extraction according to a specific pattern. Thus, the re-absorption at the midpoint represent the double of bone loss at the distal and the mesial points. Furthermore, we have observed first how the alveolar crest shifts placing along the more lingual/palatal line which divides the original alveolar crest into three parts.

Magnesium-enriched hydroxyapatite at immediate implants: a histomorphometric study in dogs

To evaluate the influence of magnesium-enriched hydroxyapatite (MHA) (SintLife(®)) on bone contour preservation and osseointegration at implants placed immediately into extraction sockets. In the mandibular pre-molar region, implants were installed immediately into extraction sockets of six Labrador dogs. MHA was placed at test sites, while the control sites did not receive augmentation materials. Implants were intended to heal in a submerged mode. After 4 months of healing, the animals were sacrificed, and ground sections were obtained for histomorphometric evaluation. After 4 months of healing, one control implant was not integrated leaving n=5 test and control implants for evaluation. Both at the test and the control sites, bone resorption occurred. While the most coronal bone-to-implant contact was similar between test and control sites, the alveolar bony crest outline was maintained to a higher degree at the buccal aspect of the test sites (loss: 0.7 mm) compared with the control sites (loss: 1.2 mm), even though this difference did not reach statistical significance. The use of MHA to fill the defect around implants placed into the alveolus immediately after tooth extraction did not contribute significantly to the maintenance of the contours of the buccal alveolar bone crest.

Influence of implant positioning in extraction sockets on osseointegration: histomorphometric analyses in dogs

To evaluate the influence of implant positioning into extraction sockets on osseointegration. Implants were installed immediately into extraction sockets in the mandibles of six Labrador dogs. In the control sites, the implants were positioned in the center of the alveolus, while in the test sites, the implants were positioned 0.8 mm deeper and more lingually. After 4 months of healing, the resorptive patterns of the alveolar crest were evaluated histomorphometrically. All implants were integrated in mineralized bone, mainly composed of mature lamellar bone. The alveolar crest underwent resorption at the control as well as at the test sites. After 4 months of healing, at the buccal aspects of the control and test sites, the location of the implant rough/smooth limit to the alveolar crest was 2 + or - 0.9 mm and 0.6 + or - 0.9 mm, respectively (P<0.05). At the lingual aspect, the bony crest was located 0.4 mm apically and 0.2 mm coronally to the implant rough/smooth limit at the control and test sites, respectively (NS). From a clinical point of view, implants installed into extraction sockets should be positioned approximately 1 mm deeper than the level of the buccal alveolar crest and in a lingual position in relation to the center of the alveolus in order to reduce or eliminate the exposure above the alveolar crest of the endosseous (rough) portion of the implant.

Osseointegration of Ti implants in buccal alveolar bone defect filled with bioactive glasses in dog mandible

AbstractAim: The aim of the present study was to investigate the amount of bone formation on titanium (Ti) implants in sites subjected to buccal alveolar crest defects and filled with different bone substitutes.Materials and methods: Mandibular premolars and first molars were extracted from five dogs. After 12 weeks, three implants (Neodent®, implant size: 3.75 × 9.0 mm, Curitiba, PR, Brazil) were bilaterally placed (total of 30 implants) in sites with buccal alveolar bone defects (length 45 mm, height 6 mm depth, 4 mm) created in the mandible. Each implantation site was randomly treated with Biosilicate (novel highly bioactive glass‐ceramic), Bioglass 45S5 (Biogran®, Implant Innovations, Barcelona, Spain), autogenous bone or no treatment. At 18 weeks after implantation, the hemi‐mandibles containing the implants were removed and processed for ground sections aiming to histological and histometric [bone‐implant contact (BIC), mineralised bone matrix between implant threads (BA) and bone matrix within mirror area (BMA)] analysis. Data were subjected to non‐parametric Kruskal–Wallis test.Results: The percentage of BIC, BA and mineralised BMA in the treated or non‐treated sites were not statistically different among the four experimental groups.Conclusion: These results indicate that the presence of the bone substitutes evaluated did not promote bone formation on Ti implants surface. In addition, tissue response to Biosilicate was similar to that of Bioglass 45S5 and autogenous bone.

Bone healing dynamics at buccal peri‐implant sites

It is common belief that immediate implant placement into extraction sites may act to preserve the alveolar process. The objective of this study was to evaluate healing dynamics at buccal peri-implant sites in relation to the dimensions of the alveolar ridge. Bilateral, critical-size, supraalveolar, peri-implant defects were created in 12 male Hound Labrador mongrel dogs following surgical horizontal cut-down of the alveolar ridge. Each jaw quadrant received three 10-mm titanium implants placed 5 mm into extraction sites of the third and fourth premolar teeth leaving 5 mm in a supraalveolar position. The mucoperiosteal flaps were advanced, adapted, and sutured for primary intention healing. Bone fluorescent markers were administered at weeks 3 and 4 postsurgery, and pre-euthanasia. Incandescent, polarized, and fluorescent light microscopies were used to assess the width of the buccal wall of the alveolar ridge and local bone remodeling over the 8-week healing interval. There was a significant association between the width of the buccal alveolar ridge and extent of bone resorption evaluated by incandescent and fluorescent light microscopy. A non-linear association was observed between the buccal ridge width and resorption of the alveolar ridge. A 2-mm threshold was established to account for this non-linearity. The strength of this association was two times greater in specimens with a buccal ridge width <2 mm compared with a wider ridge (beta=1.62 vs. 0.80) observed by fluorescent light microscopy. Accordingly, mean buccal resorption was significantly greater when the ridge width was <2 mm. Fluorescent light microscopy consistently showed greater buccal resorption compared with incandescent light microscopy (P<0.05). Agreement between the examination techniques was low (concordance correlation coefficient=0.49), especially for higher values of buccal resorption. When implants are placed into extraction sites, proximity to the buccal alveolar crest appears a major consideration. The observations herein suggest that the width of the buccal alveolar ridge should be at least 2 mm to maintain the alveolar bone level. These observations likely have general implications for implant placement using most surgical protocols.

Periodontal effects of rapid maxillary expansion with tooth-tissue-borne and tooth-borne expanders: A computed tomography evaluation

The force delivered during rapid maxillary expansion (RME) produces areas of compression on the periodontal ligament of the supporting teeth. The resulting alveolar bone resorption can lead to unwanted tooth movement in the same direction. The purpose of this study was to evaluate periodontal changes by means of computed tomography after RME with tooth-tissue-borne and tooth-borne expanders. The sample comprised 8 girls, 11 to 14 years old, with Class I or II malocclusions with unilateral or bilateral posterior crossbites Four girls were treated with tooth-tissue-borne Haas-type expanders, and 4 were treated with tooth-borne Hyrax expanders. The appliances were activated up to the full 7-mm capacity of the expansion screw. Spiral CT scans were taken before expansion and after the 3-month retention period when the expander was removed. One-millimeter thick axial sections were exposed parallel to the palatal plane, comprising the dentoalveolar area and the base of the maxilla up to the inferior third of the nasal cavity. Multiplanar reconstruction was used to measure buccal and lingual bone plate thickness and buccal alveolar bone crest level by means of the computerized method. RME reduced the buccal bone plate thickness of supporting teeth 0.6 to 0.9 mm and increased the lingual bone plate thickness 0.8 to 1.3 mm. The increase in lingual bone plate thickness of the maxillary posterior teeth was greater in the tooth-borne expansion group than in the tooth-tissue-borne group. RME induced bone dehiscences on the anchorage teeth's buccal aspect (7.1 +/- 4.6 mm at the first premolars and 3.8 +/- 4.4 mm at the mesiobuccal area of the first molars), especially in subjects with thinner buccal bone plates. The tooth-borne expander produced greater reduction of first premolar buccal alveolar bone crest level than did the tooth-tissue-borne expander.

Avaliação da expansão rápida da maxila por meio da tomografia computadorizada: relato de um caso

Este trabalho descreve os efeitos dentoesqueléticos e periodontais da expansão rápida da maxila (ERM), avaliados por meio da tomografia computadorizada (TC), em uma jovem de 11,6 anos de idade com má oclusão de Classe I e mordida cruzada posterior unilateral funcional. Durante a fase ativa da ERM, o expansor dentossuportado com parafuso Hyrax foi ativado 7mm. A paciente submeteu-se ao exame de TC helicoidal, antes da expansão e após a remoção do aparelho expansor, findo o período de três meses de contenção. Realizaram-se cortes axiais, de um milímetro de espessura, paralelamente ao plano palatino, englobando as regiões dentoalveolar e basal da maxila, até o terço inferior da cavidade nasal. Utilizando-se o recurso de reconstruções multiplanares, mensuraram-se pelo método computadorizado: as dimensões transversas maxilares, a inclinação dos dentes posteriores, a espessura das tábuas ósseas vestibular e lingual, e o nível da crista óssea alveolar vestibular. A expansão rápida da maaxila ocasionou um significante aumento transverso em todas as regiões aferidas, com magnitude decrescente do arco dentário para a base óssea. Os dentes posteriores foram movimentados para vestibular, com um componente de inclinação e translação associados. Tal efeito ortodôntico ocasionou uma redução na espessura da tábua óssea vestibular, e um concomitante aumento na espessura da tábua óssea lingual. Após a expansão, observou-se o desenvolvimento de deiscências ósseas por vestibular dos dentes de ancoragem.

Effect of allogenic freeze-dried demineralized bone matrix on guided tissue regeneration in dogs.

This randomized, split-mouth study was designed to evaluate the adjunctive effect of allogenic, freeze-dried, demineralized bone matrix (DBM) to guided tissue regeneration (GTR). Contralateral fenestration defects (6 x 4 mm) were created 6 mm apical to the buccal alveolar crest on maxillary canine teeth in 6 beagle dogs. DBM was implanted into one randomly selected fenestration defect. Expanded polytetrafluoroethylene (ePTFE) membranes were used to provide bilateral GTR. Tissue blocks including defects with overlying membranes and soft tissues were harvested following a four-week healing interval and prepared for histometric analysis. Differences between GTR+DBM and GTR defects were evaluated using a paired t-test (N = 6). DBM was discernible in all GTR+DBM defects with limited, if any, evidence of bone metabolic activity. Rather, the DBM particles appeared solidified within a dense connective tissue matrix, often in close contact to the instrumented root. There were no statistically significant differences between the GTR+DBM versus the GTR condition for any histometric parameter examined. Fenestration defect height averaged 3.7+/-0.3 and 3.9+/-0.3 mm, total bone regeneration 0.8+/-0.6 and 1.5+/-0.8 mm, and total cementum regeneration 2.0+/-1.3 and 1.6+/-1.7 mm for GTR+DBM and GTR defects, respectively. The histologic and histometric observations, in concert, suggest that allogenic freeze-dried DBM has no adjunctive effect to GTR in periodontal fenestration defects over a four-week healing interval. The critical findings were 1) the DBM particles remained, embedded in dense connective tissue without evidence of bone metabolic activity; and 2) limited and similar amounts of bone and cementum regeneration were observed for both the GTR+DBM and GTR defects.

Guided tissue regeneration using a bioabsorbable membrane in the treatment of human buccal recession. A re-entry study.

A surgical technique involving a bioabsorbable membrane was used to treat localized buccal recession defects of between 2 and 5 mm on 17 sites in 13 patients. A conventional flap for coronal repositioning was raised consisting of a trapezoid flap with de-epithelialization of papillae, and the root surface planed back to reduce its convexity. The polylactate membrane with internal spacer bars was placed over the root surface with its coronal edge as near to the cemento-enamel junction (CEJ) as possible. This was held in place by a bioabsorbable retaining suture around the root, and the flap was coronally repositioned to cover the membrane. The patients were prescribed tetracycline for 2 weeks postsurgically, the sutures removed after 4 weeks, and cleaning procedures in the area reinstated after 6 weeks. Measurements were made using a custom made stent, and subjected to a Wilcoxon signed ranked analysis. These were clinical recession, clinical attachment level, probing depth, width of attached gingiva and the level of the buccal alveolar crest. The healing was monitored for a minimum of 1 year, and a surgical re-entry procedure was performed on 11 sites. The new buccal alveolar crest position was measured. This procedure resulted in a clinical and statistically significant reduction in clinical recession of 2.4 +/- 0.2 mm, a gain in attachment level of 2.7 +/- 0.2 mm, a gain in root coverage of 76 +/- 6% (P < 0.002), and a regeneration of buccal bone in all cases, with an average of 2.0 +/- 0.1 mm (P < 0.0023). This study shows that the use of a bioabsorbable membrane will predictably and significantly increase root coverage and regenerate buccal bone when used to treat localized buccal recession defects.