Polyethylene ribbon and fixed orthodontic retention and porcelain veneers: solving an esthetic dilemma

The patient, a 58-year-old woman, had started orthodontic treatment to correct spacing between the maxillary anterior teeth 6 year prior to presentation with a chief complaint of tooth discoloration and spacing. The treatment had consisted of the use of a removable appliance to retract the maxillary anterior teeth. The patient continued to wear the appliance sporadically. When she presented, the maxillary incisors were in primary occlusal trauma with Grade 2 mobility. The patient discontinued wearing the appliance. The periodontal condition was addressed with initial therapy. As part of the treatment plan to stabilize the maxillary anterior teeth and provide the patient with an esthetic result, it was decided to do a limited occlusal adjustment of the maxillary anterior teeth to control fremitus, and to place a fixed, composite resin, polyethylene ribbon-reinforced splint, using a facial approach. The esthetic restoration of these teeth was accomplished with bonded porcelain veneers.     

Esthetic and prosthetic procedures in single-tooth replacement

Loss of anterior maxillary teeth always results in bone resorption and loss of interdental papillae, and the resorption makes a single tooth replacement by a dental implant very difficult. When infections have been present and the patient's history shows previous surgery at the apex of the root, bone destruction is substantial, which results in an increased resorption defect, thereby further increasing the aesthetic and prosthetic problems. This paper describes the steps necessary for implant surgery and the prosthetics; a brief summary is provided. The quality and quantity of bone, along with the space available between the adjacent teeth, are the basic factors in treatment planning and determine the type of implant to be used. Some resorption and bone defects are usually present after a tooth extraction, and bone regeneration procedures can be performed either before or simultaneously with the implant placement, with numerous flap designs available. Soft tissue augmentation can be achieved by taking a connective tissue graft from the palatal side. Antirotational devices (eg, hex lock abutments) are necessary for all implants in single tooth replacement. Screw-retained abutments can be used in posterior areas and in angled positions in facial areas as well. With proper single tooth implant position, cementation of laboratory fabricated crowns can be considered.     

A new approach in restorative treatment of external root resorption. A case report

This case report describes the treatment of an external root resorption with extensive loss of tooth structure and bone at the labial surface of an upper left central incisor. The area of bone loss and root resorption was surgically exposed and an impression was taken using curing silicone. An individual ceramic insert was fabricated, allowing endodontic retreatment through an artificial root canal. The insert was incorporated using a dentin bonding system and a dual curing luting composite. Following endodontic retreatment and internal bleaching, a ceramic veneer was bonded to the tooth to obtain good esthetics and to improve stability. Twenty months after surgical treatment no further root resorption could be detected radiographically. A shallow residual pocket but no bleeding on probing was found.     

Swing-lock design considerations for obturator frameworks

The conventional and swing-lock (S/L) obturator prostheses can be highly effective in restoring maxillary defects when careful attention is paid to the principles of framework design. Although the S/L modality has been available since the mid 1960s, its use in maxillofacial prosthetics has been limited, and little information is available in the literature to guide the practitioner. This modality offers a conservative design option that lies somewhere between the conventionally designed obturator prosthesis and the prosthesis designed to use extensive fixed reconstruction or endosseous implants. When the S/L obturator is considered, single, double, or dual labial bar designs are possible and may be required by the length and complexities of the arc of closure. Such designs provide a flexible labial bar that transmits less stress to abutment teeth. This article reviewed conventional obturator framework designs and compared them with S/L designs for similar patient categories.     

The use of tooth thickness in predicting intermaxillary tooth-size discrepancies

Intermaxillary tooth-size discrepancies can be assessed using a diagnostic setup or predicted using a mathematical formula, such as the Bolton analysis. However, variations in tooth thickness may produce inaccuracies in the Bolton analysis ratio. To date, no method for incorporating tooth thickness into discrepancy prediction has been proposed. The purpose of this study was to design and test a new method of predicting anterior tooth-size discrepancy that takes into account tooth thickness and width. Forty-four positioner setup models were set to ideal overbite (2.5 mm) and occlusion (Class I canine relationship). Interproximal gaps between the maxillary or mandibular central incisors were allowed in order to optimize tip and torque. The mesiodistal width of all anterior teeth and the labiolingual thickness of the maxillary incisors were measured on these idealized setups to the nearest 0.1 mm. Actual intermaxillary anterior ratios were then calculated. A new method of prediction was developed by assuming a linear relationship between tooth thickness and ideal intermaxillary ratio. Errors in Bolton's method were compared with the new method. The results showed wide variations in mesiodistal tooth widths, tooth thicknesses, and intermaxillary anterior ratios in orthodontically treated patients. The correlation coefficient between the intermaxillary ratio and tooth thickness was r = 0.68 when tooth thickness was < 2.75 mm, and r = 0.28 when tooth thickness was > or = 2.75 mm. The mean absolute errors in predicting the actual intermaxillary ideal ratio was 1.29 +/- 0.81 for Bolton's ratio and 0.84 +/- 0.46 for the new prediction formula. These new formulas were better than Bolton's ratio in predicting tooth-size discrepancies (p = 0.003). Tooth thickness combined with mesiodistal width may be useful in predicting intermaxillary tooth-size discrepancies.     

The extracted tooth pontic--provisional replacement during bone graft and implant healing

When tooth extraction is required, a provisional restoration may be utilized as an interim prosthesis during bone graft and implant healing. The selection of provisional replacement of the anterior teeth following extraction may have a direct influence on the success of the definitive tooth replacement. This article describes a technique for using the extracted tooth or a denture tooth as an interim prosthesis during bone graft and implant healing. This method of provisionalization offers several advantages, including no adjacent tooth preparation, natural appearance, and retention of the papillae.     

An immediate-extraction anterior single-tooth replacement utilizing a fiber-reinforced dual-component bridge

Replacement of a single anterior tooth is an extremely challenging procedure. Numerous objective and subjective factors must be evaluated by the interdisciplinary team in the determination of the appropriate restorative method. This article reviews the restorative options and describes an emerging treatment modality--the fiber-reinforced dual-component bridge--as the option selected in a case requiring an immediate extraction of the maxillary right central incisor. The pertinent technology, indications, contraindications, and current clinical technique of dual-component nonmetallic prostheses are examined.     

The sinus lift graft: basic technique and variations

Following an early controversy concerning its efficacy, the sinus lift and graft technique is now considered to be a state-of-the-art surgery. In 1975, Tatum introduced the technique that increased maxillary bone height by placing graft material under the maxillary sinus and Schneiderian membrane; by the early 1990s, a modification of Tatum's original technique had become a standard procedure. This article describes and illustrates three variations of the basic sinus lift surgery and graft operation--the hinge osteotomy, the elevated osteotomy, and the complete osteotomy. Additional considerations affecting the surgical outcome are also discussed as is the management of possible complications. The learning objective of this article is to obtain up-to-date information regarding the basic technique and variations of the sinus lift procedure to the general practitioner as well as the specialist.     

A twin study of dental dimension. II. Independent genetic determinants

To demonstrate the presence of independent genetic determinants of multiple correlated tooth dimensions from twin data, a multivariate analysis was performed on the covariance matrices of monozygotic and dizygotic within-pair differences for mesiodistal and buccolingual dimensions of 28 teeth of the secondary dentition. The results provided strong evidences that the correlation among tooth dimensions is primarily genetic in origin, probably attributable to the pleiotropic action of either independent genes or groups of genes. Among the genetic factors that were identified, one appeared to affect the maxillary teeth in general while a second influenced primarily the anterior mandibular teeth. There was a striking tendency for homologous measurements on the right and left sides to be associated with the same genetic factor. In contrast, genetic determination of the maxillary and mandibular dentition seemed to be independent of each other, and a wider range of genetic factors were found to influence the mandibular than the maxillary teeth, suggesting that a differential degree of evolutionary stability may have been achieved in the teeth of the two jaws.     

A prospective evaluation of Bass, Bionator and Twin Block appliances. Part I--The hard tissues

A prospective clinical study with a random allocation of 47 adolescent patients to three different functional appliance groups was established and compared with an untreated control group over a 9-month period. Treatment was undertaken with either a Bionator, Twin Block, or Bass appliance. Pre- and post-treatment cephalograms were used to quantify the skeletal and dentoalveolar changes produced by the appliances and compared with those observed in the control group as a result of growth. Both the Bionator and Twin Block appliances demonstrated a statistically significant increase in mandibular length (3.9 +/- 2.7 mm; 3.7 +/- 2.1 mm, respectively) compared with the control group (P < 0.05), with an anterior movement of pogonion and point B. Highly statistically significant increases (P < 0.01) were seen in lower face heights for all the appliance groups compared with the control group. The Twin Block group showed the least forward movement of point A due to a change in the inclination of the maxillary plane. The Bionator and Twin Block groups showed statistically significant reductions in the inclination of the upper incisors to the maxillary plane (P < 0.05). The Bass group showed minimal change in the inclination of the lower labial segment to the mandibular plane. The Bionator group demonstrated the greatest proclination of the lower labial segment (4.0 +/- 3.6 degrees). Clinically important changes were measured in all the appliance groups when compared with the control group. Differences were also identified between the functional appliance groups. The Twin Block appliance and, to a lesser extent, the Bionator appeared the most effective in producing sagittal and vertical changes.     

Surgical treatment of unilateral alveolar cleft

In this study, 16 cases of unilateral alveolar cleft with cleft lip and palate were repaired with autografts of cancellous bone (13 cases) or hydroxyapatite (3 cases). The grafts were covered by reflected mucoperiosteal flaps and a mucosal flap from the upper lip. Twelve of the thirteen cases were followed up for 1-5 years. Nine of whom using cancellous bone had bony continuity of the maxilla and 7 cases erupted permanent maxillary canines within the area of autografts. None of the 3 cases using hydroxyapatite erupted a canine tooth. The results showed that autograft was better than hydroxyapatite in terms of maxillary canine eruption.     

Outcomes of the surgical exposure, bonding and eruption of 82 impacted maxillary canines

BACKGROUND: Advances in bonding techniques and materials allow for reliable bracket placement on ectopically positioned teeth. This prospective study evaluates the outcome of forced orthodontic eruption of impacted canine teeth in both palatal and labial positions. METHODS: Eighty-two impacted maxillary canines in 54 patients were included in the study and were observed for 18 to 30 months after exposure. Following exposure by means of a palatal flap or an apically repositioned buccal flap, an orthodontic traction hook, with a ligation chain attached, was bonded to each impacted tooth using a light cured orthodontic resin cement. A periodontal dressing was placed over the surgical site for a period of time. RESULTS: All teeth were successfully erupted. Complications consisted of: failure of initial bond, at the time of surgery, which required rebonding; premature debonding at the time of pack removal and; debonding of brackets during orthodontic eruption. There was no infection, eruption failure, ankylosis, resorption or periodontal defect (pocket greater than 3 mm) associated with any of the exposed teeth. Attached gingiva of less than 3 mm was seen in only two of the buccally positioned canines (9%). CONCLUSION: Forced orthodontic eruption of impacted maxillary canines with a well bonded orthodontic traction hook and ligation chain, used in conjunction with a palatal flap or an apically repositioned labial flap, results in predictable orthodontic eruption with few complications.     

A dosimetric analysis of behavioral effects of acute toluene exposure in rats and humans

Contradictory findings from studies on pretreatment malalignment as a risk factor for relapse of maxillary incisor alignment may be due to inappropriate sample selection and measurement technique. In an attempt to clarify the issue, 745 sets of study models made before (T1) and after (T2) orthodontic treatment and at long-term out of retention (T3) were screened. On the basis of the configuration of the maxillary anterior teeth on the T3 study models, three groups were established: one with significant spacing (group 1, n = 30); one with significant irregularity (group 2, n = 49); and one with perfect alignment (group 3, n = 28). The occlusal surfaces of the 321 maxillary study models at T1, T2, and T3 were photocopied and the tooth anatomic contact points digitized. An algorithm was used to fit the dental arch to the digitized points. Amount of incisor rotation and anatomic contact point displacement of the maxillary anterior teeth relative to the dental arch were computer generated. Interdental spaces in the maxillary anterior segment, as well as overjet and overbite, were measured manually. Nonstructural data were collected from the charts. Logistic regression analyses revealed that irregularity was associated with greater anatomic contact displacement and with greater incisor rotation both at T1 and T2 (P < 0.01). Similar analyses also revealed that spacing was associated with greater interdental spaces at T1 and T2 (P < 0.01). Correlation analyses revealed that the pattern of pretreatment rotational displacement has a strong tendency to repeat itself after retention (P < 0.001), as opposed to the pattern of contact point displacement and interdental spacing.     

Periodontal surgical management of impacted maxillary cuspids

The diagnosis and surgical management of impacted maxillary cuspids has been discussed. The general practitioner must be aware of the normal and abnormal pathways as well as the correct age of eruption of the maxillary cuspid. The proper management of impacted maxillary canine teeth requires the careful cooperation and communication between the general practitioner, the orthodontist and the periodontist or oral surgeon.     

Superficial hemangiomas: associations and management

A new design of single tooth implant (AstraTech, Molndal Sweden) featuring a microthreaded conical neck and TiO blast surface was evaluated clinically and radiographically after 2 years in function. Fifteen patients (age range 16 to 48) with missing maxillary anterior teeth (6 central incisors, 8 laterals, 1 bicuspid) had 4, 13 mm and 11, 15 mm implants placed under local anaesthesia and left for a period of 6 months before exposure and abutment connection/crown fabrication. All patients were seen at 4 to 6 monthly intervals for hygienist maintenance. Radiographs using Rinn holders and a long cone technique were taken at the crown insertion and after 1 year (14 subjects) and 2 years (12 subjects). All implants were successfully integrated at stage 2, and no implants have been lost. The internal conical seal design of the abutment/implant interface facilitated connection and there were no cases of abutment screw loosening. No soft tissue problems were observed, and the gingival morphology/health was well maintained. One crown was recemented after 18 months in function, and 1 crown was replaced because of a fracture to the porcelain incisal edge. At crown insertion, the mean bone level was 0.46 to 0.48 mm apical to the top of the implant and there were no statistically significant changes in the bone level over the 2 years of the study. In conclusion, the single tooth Astra implants were highly successful and bone changes within the first 2 years of function were comparable with other systems reporting high long-term success rates.     

A novel adrenaline derivative, AZ002, and its hypoglycemic action in yellow KK mice

A new device has been designed to provide anchorage for orthodontic tooth movement. It is a disk, textured and hydroxylapatite coated on one side, with an internal thread on the other side. It is placed on palatal bone and, after integration, can be connected to teeth for anchorage. This article reviews a dog study demonstrating unilateral tooth movement towards the "onplant" and a monkey study mimicking its use to anchor the molars for anterior retraction.     

Oral findings in a group of newborn Swedish children

Oral examinations were performed of 1021 newborn Swedish children, of whom 101 were re-examined after 2-3 or 4-5 months. The most common findings, registered in 74.9% of the children, were of oral mucosal cysts situated either palatally or on the alveolar ridges. The majority of the palatal cysts disappeared shortly after birth, and some alveolar cysts appeared after birth. Ankyloglossia was found in 2.5% of the children, and Fordyce spots in 1.0%. No natal teeth were found. The upper labial frenum was attached to the crest of the alveolar ridge in 76.7% of the children, palatally in 16.7% and buccally in 6.7%. The relationship of the alveolar ridges was recorded: the anterior segment of the mandibular ridge was distal to the maxillary in 99% of cases, and, posteriorly, the mandibular ridges were lingual to the maxillary in 97.6%. An open bite was found in 39.8% of the children.     

Microvascular system of the rat incisor enamel organ. A scanning electron microscopic study of vascular corrosion casts

The rat incisor is a commonly used model in studies of tooth eruption, amelogenesis and effects of mechanical loading on the dental and periodontal tissues. The purpose of this study was to assess the three-dimensional architecture of the microvascular bed of the rat incisor enamel organ, to describe the direction of blood flow, and to provide a histometric assessment of the vascular categories that can be statistically analyzed. Vascular corrosion casts were prepared and examined by scanning electron microscopy. The microvasculature of the labial periodontal space was arranged in three distinct layers. The inner layer in direct relation to the enamel organ consisted of a capillary network which was drained by short venules at the cemento-enamel junction. The intermediate layer consisted of arterioles oriented parallel to the long axis of the incisor mainly mid-labially, branching off smaller arterioles to the capillary network. The outer layer was formed by flattened sinusoid vessels of larger caliber. Blood supply was from the anterior superior alveolar artery branches through the arterioles into the capillary network. Drainage was postero-laterally along the cemento-enamel junction via short venules which emptied into the sinusoid vessels, finally to flow through Volkmann's canals into the alveolar bone via small venules. The findings demonstrate that the microvasculature of the rat incisor enamel organ has an exceptionally high level of physiologically-adapted structural organization.     

A study of anterior guidance

PURPOSE: This study focuses on the curvature and inclination of the lingual surfaces of the maxillary anterior teeth from the transition point on the cingulum to the incisal edge. MATERIALS AND METHODS: On 32 sets of mounted casts, 768 measurements were made of the curvature of the lingual surfaces utilizing radius gauges. The inclination of the lingual surface relative to the occlusal plane was recorded. The relationship of the incisal edge of the mandibular teeth to the transition point on the cingulum of the maxillary teeth was determined. Centric occlusion contact was noted on each tooth. RESULTS: Significant differences were found between the measured areas of any one tooth and between the types of teeth. The average radius ranged from 20.5 mm on the mesial ridge of the canine to 5.3 mm in the fossa of the central. The average inclination of the lingual surfaces was 46 degrees. In centric occlusion, 97% of the canines and 59% of the centrals and laterals were in contact with the opposing teeth. These contacts occurred 2.8 mm incisal to the transition point. The centrals contracted two opposing teeth (45%), and canines contacted one opposing tooth (53%). CONCLUSIONS: The function and curvature of the incisor teeth vary considerably from those of the canines. Overcontouring the lingual surfaces of the maxillary incisors to gain contact is not normal and may be detrimental.     

Quantitative evaluation of newly formed bone in the alveolar wall surrounding the root during the initial stage of experimental tooth movement in the rat

By using a chronological lead-labelling technique and computer image analysis the volume of this newly formed bone was evaluated. Rat maxillary first molars were moved mesially by a fixed, closed coil-spring appliance for 6 days using three different magnitudes of initial tensile force (27, 60 and 136 g). Sham-treated rats wearing an inactivated appliance were used for the control study. All animals were injected twice intraperitoneally with lead-disodium EDTA, 3 hr before the beginning and 3 hr before the end of treatment. The unit volumes of newly formed bone (mm3/mm2) were assessed with reference to lead-labelling lines in the alveolar walls of the root socket by computer image analysis. In the control group, two distinct lead-labelling lines indicated continuous bone formation on the mesial side of the root sockets, but only a jagged line was found on the distal side. After experimental mesial tooth movement, only a single lead line could be found on the mesial/pressure side of the root sockets; on the distal/tension side, a wide layer could be detected between the two lead lines. The volume of newly formed bone on the distal/tension side in the experimental groups was significantly greater than that in the control group. However, there was no significant difference in the volumes of newly formed bone among the three experimental groups. The study demonstrates that the volume of newly formed bone in the alveolar walls during the initial stage of tooth movement can be quantified and that the magnitude of the tensile force of tooth movement may not influence directly the volume of newly formed bone in the alveolar wall on the tension side.